One commentator has observed that, notwithstanding the high unemployment resulting from the loss of full passports during 1981–2002, the level of loyalty to the British monarchy by the St Helena population is probably not exceeded in any other part of the world. King George VI is the only reigning monarch to have visited the island. This was in 1947 when the King, accompanied by Queen Elizabeth (later the Queen Mother), Princess Elizabeth (later Queen Elizabeth II) and Princess Margaret were travelling to South Africa. Prince Philip arrived at St Helena in 1957 and then his son Prince Andrew visited as a member of the armed forces in 1984 and his sister the Princess Royal arrived in 2002.

What caused high unemployment on the island?

loss of full passports

Who is the only reigning Monarch to have visited the island?

King George VI

What year did King George VI visit the island?

When did Prince Phillip arrive in Saint Helena?

Prince Andrews, son of Prince Phillip visited in what year?


In 2012, the government of St. Helena funded the creation of the St. Helena Human Rights Action Plan 2012-2015. Work is being done under this action plan, including publishing awareness-raising articles in local newspapers, providing support for members of the public with human rights queries, and extending several UN Conventions on human rights to St. Helena.

What did the government of Saint Helena fund in 2012?

St. Helena Human Rights Action Plan 2012-2015

What kind of articles were published to help this plan?

awareness-raising articles

How was support for members of the public given?

with human rights queries


In recent years[when?], there have been reports of child abuse in St Helena. Britain’s Foreign and Commonwealth Office (FCO) has been accused of lying to the United Nations about child abuse in St Helena to cover up allegations, including cases of a police officer having raped a four-year-old girl and of a police officer having mutilated a two-year-old.

What has been more prominently reported in recent years in Saint Helena?

reports of child abuse

Who has been accused of lying about the child abuse issue of Saint Helena?

Britain’s Foreign and Commonwealth Office

Who has Britain’s Foreign and Commonwealth Office been accused of lying to about child abuse?

the United Nations


St Helena has long been known for its high proportion of endemic birds and vascular plants. The highland areas contain most of the 400 endemic species recognised to date. Much of the island has been identified by BirdLife International as being important for bird conservation, especially the endemic Saint Helena plover or wirebird, and for seabirds breeding on the offshore islets and stacks, in the north-east and the south-west Important Bird Areas. On the basis of these endemics and an exceptional range of habitats, Saint Helena is on the United Kingdom's tentative list for future UNESCO World Heritage Sites.

Saint Helena has a high proportion of what kind of birds?

endemic

What kind of plants are common on Saint Helena?

vascular

What organization identified Saint Helena as important for bird conservation?

BirdLife International

Saint Helena is on the United Kingdom's list for future what?

UNESCO World Heritage Sites


St Helena's biodiversity, however, also includes marine vertebrates, invertebrates (freshwater, terrestrial and marine), fungi (including lichen-forming species), non-vascular plants, seaweeds and other biological groups. To date, very little is known about these, although more than 200 lichen-forming fungi have been recorded, including 9 endemics, suggesting that many significant discoveries remain to be made.

How many lichen forming fungi have been recorded on the island?

more than 200

How many endemic species of fungi have been found?

What kind of invertebrates have been found on the island?

freshwater, terrestrial and marine


The island had a monocrop economy until 1966, based on the cultivation and processing of New Zealand flax for rope and string. St Helena's economy is now weak, and is almost entirely sustained by aid from the British government. The public sector dominates the economy, accounting for about 50% of gross domestic product. Inflation was running at 4% in 2005. There have been increases in the cost of fuel, power and all imported goods.

What kind of crop economy did the Island originally have?

monocrop

What year did the crop economy change?

What was produced during the time the Island was monocrop?

flax

Saint Helena's economy is now almost completely sustained by what?

aid from the British government

How much % of production does the public sector cover?


The tourist industry is heavily based on the promotion of Napoleon's imprisonment. A golf course also exists and the possibility for sportfishing tourism is great. Three hotels operate on the island but the arrival of tourists is directly linked to the arrival and departure schedule of the RMS St Helena. Some 3,200 short-term visitors arrived on the island in 2013.

What is the tourist industry mostly based around?

the promotion of Napoleon's imprisonment

What kind of fishing tourism occurs on the island?

sportfishing

How many hotels are on the island?

Tourism is completely based on what arriving to the island?

the RMS St Helena


Saint Helena produces what is said to be the most expensive coffee in the world. It also produces and exports Tungi Spirit, made from the fruit of the prickly or cactus pears, Opuntia ficus-indica ("Tungi" is the local St Helenian name for the plant). Ascension Island, Tristan da Cunha and Saint Helena all issue their own postage stamps which provide a significant income.

What does Saint Helena have the most expensive of?

coffee

What is Tungi Spirit made out of?

Opuntia ficus-indica

Ascension Island, Tristan da Cunha and Saint Helena all issue their own what?

postage stamps


Quoted at constant 2002 prices, GDP fell from £12 million in 1999-2000 to £11 million in 2005-06. Imports are mainly from the UK and South Africa and amounted to £6.4 million in 2004-05 (quoted on an FOB basis). Exports are much smaller, amounting to £0.2 million in 2004-05. Exports are mainly fish and coffee; Philatelic sales were £0.06 million in 2004-05. The limited number of visiting tourists spent about £0.4 million in 2004-05, representing a contribution to GDP of 3%.

What was the GDP of the island in 1999-2000?

£12 million

By 2006 the GDP had dropped to what?

£11 million

Imports to the island mostly occur from what countries?

the UK and South Africa

What are the main exports of the island?

fish and coffee

Tourists spent how much in  2004-05?

£0.4 million


Public expenditure rose from £10 million in 2001-02 to £12 million in 2005-06 to £28m in 2012-13. The contribution of UK budgetary aid to total SHG government expenditure rose from £4.6 million in to £6.4 million to £12.1 million over the same period. Wages and salaries represent about 38% of recurrent expenditure.

How much was public expenditure on the island in 2001-2002?

£10 million

By 2005-06 public expenditure had risen to what?

£12 million

In 2012-2013, public expenditure was what?

UK aid had risen to how much in the same period?

£12.1 million

Wages and salaries represent how much % of the island's expenditure?


Unemployment levels are low (31 individuals in 2013, compared to 50 in 2004 and 342 in 1998). Employment is dominated by the public sector, the number of government positions has fallen from 1,142 in 2006 to just over 800 in 2013. St Helena’s private sector employs approximately 45% of the employed labour force and is largely dominated by small and micro businesses with 218 private businesses employing 886 in 2004.

How many individuals were unemployed on the island in 2013?

Employment on the island is dominated by what sector?

public

In 2013 the number of government jobs was what?

What % of people are employed in the private sector in Saint Helena?

How many private businesses employee people on Saint Helena?


Household survey results suggest the percentage of households spending less than £20 per week on a per capita basis fell from 27% to 8% between 2000 and 2004, implying a decline in income poverty. Nevertheless, 22% of the population claimed social security benefit in 2006/7, most of them aged over 60, a sector that represents 20% of the population.

What % of households were spending less than £20 per week in 2004

What % of the population claimed social security benefits in 2006/7?

How much of the population is over age 60?


In 1821, Saul Solomon issued a 70,560 copper tokens worth a halfpenny each Payable at St Helena by Solomon, Dickson and Taylor – presumably London partners – that circulated alongside the East India Company's local coinage until the Crown took over the island in 1836. The coin remains readily available to collectors.

How many copper tokens were Issued in 1821?

Who issued the copper tokens in 1821?

Saul Solomon

How much was each copper token worth?

a halfpenny

When did the Crown take over the island?


Today Saint Helena has its own currency, the Saint Helena pound, which is at parity with the pound sterling. The government of Saint Helena produces its own coinage and banknotes. The Bank of Saint Helena was established on Saint Helena and Ascension Island in 2004. It has branches in Jamestown on Saint Helena, and Georgetown, Ascension Island and it took over the business of the St. Helena government savings bank and Ascension Island Savings Bank.

What is the Saint Helena currency?

the Saint Helena pound

The government of Saint Helena produces it's own what?

coinage and banknotes

What year was the Bank of Saint Helena established?

The Saint Helena pound is at parity with what other currency?

pound sterling


Saint Helena is one of the most remote islands in the world, has one commercial airport under construction, and travel to the island is by ship only. A large military airfield is located on Ascension Island, with two Friday flights to RAF Brize Norton, England (as from September 2010). These RAF flights offer a limited number of seats to civilians.

How many commercial airports are under construction in Saint Helena?

What is the only method of travel currently available to Saint Helena?

ship

A large airfield is located on what portion of the island?

Ascension Island

What kind of flights are offered to limited civilians?

RAF flights


The ship RMS Saint Helena runs between St Helena and Cape Town on a 5-day voyage, also visiting Ascension Island and Walvis Bay, and occasionally voyaging north to Tenerife and Portland, UK. It berths in James Bay, St Helena approximately thirty times per year. The RMS Saint Helena was due for decommissioning in 2010. However, its service life has been extended indefinitely until the airport is completed.

What ship runs between Saint Helena and Cape town on 5 day voyages?

RMS Saint Helena

What year was the RMS Saint Helena supposed to be decommissioned?

What needs to be completed before the RMS Saint Helena can be decommissioned?

the airport


After a long period of rumour and consultation, the British government announced plans to construct an airport in Saint Helena in March 2005. The airport was expected to be completed by 2010. However an approved bidder, the Italian firm Impregilo, was not chosen until 2008, and then the project was put on hold in November 2008, allegedly due to new financial pressures brought on by the Financial crisis of 2007–2010. By January 2009, construction had not commenced and no final contracts had been signed. Governor Andrew Gurr departed for London in an attempt to speed up the process and solve the problems.

When was the construction of an airport in Saint Helena announced?

March 2005

The airport was expected to be completed by what year?

Who was the approved bidder for the airport?

Impregilo

Which governor departed to London to try to speed up the construction of the airport?

Andrew Gurr


On 22 July 2010, the British government agreed to help pay for the new airport using taxpayer money. In November 2011 a new deal between the British government and South African civil engineering company Basil Read was signed and the airport was scheduled to open in February 2016, with flights to and from South Africa and the UK. In March 2015 South African airline Comair became the preferred bidder to provide weekly air service between the island and Johannesburg, starting from 2016.

When did the British government agree to help pay for the new airport in Saint Helena?

22 July 2010

Which south african company is helping to engineer the airport?

Basil Read

The new airport opening date is when?

February 2016

Which countries will be able to fly to Saint Helena using the airport?

South Africa and the UK

Which airline will provide weekly service to Saint Helena?

Comair


The first aircraft, a South African Beechcraft King Air 200, landed at the new airport on 15 September 2015, prior to conducting a series of flights to calibrate the airport's radio navigation equipment.

What kind of aircraft was the first to land at the new airport?

South African Beechcraft King Air 200

What date did the aircraft land at the new airport?

15 September 2015

What are they calibrating via test flights at the airport?

the airport's radio navigation equipment.


The first helicopter landing at the new airfield was conducted by the Wildcat HMA.2 ZZ377 from 825 Squadron 201 Flight, embarked on visiting HMS Lancaster on 23 October 2015.

Who conducted the first helicopter landing at the airfield?

Wildcat HMA.2 ZZ377

Where did the helicopter embark on visiting?

HMS Lancaster

When did the aircraft visit HMS Lancaster?

23 October 2015


A minibus offers a basic service to carry people around Saint Helena, with most services designed to take people into Jamestown for a few hours on weekdays to conduct their business. Car hire is available for visitors.

What kind of vehicle offers basic transportation to people in Saint Helena?

A minibus

Where does the minibus travel to?

Jamestown

On what days does the minibus take people into Jamestown?

weekdays


Radio St Helena, which started operations on Christmas Day 1967, provided a local radio service that had a range of about 100 km (62 mi) from the island, and also broadcast internationally on shortwave radio (11092.5 kHz) on one day a year. The station presented news, features and music in collaboration with its sister newspaper, the St Helena Herald. It closed on 25 December 2012 to make way for a new three-channel FM service, also funded by St. Helena Government and run by the South Atlantic Media Services (formerly St. Helena Broadcasting (Guarantee) Corporation).

What day did Radio Saint Helena start operations?

Christmas Day 1967

What was the range of Radio Saint Helena in miles?

How many days a year was Radio Saint Helena broadcast internationally?

What newspaper did Radio Saint Helena collaborate with?

St Helena Herald

What day was Saint Helena Radio shut down?

25 December 2012


Saint FM provided a local radio service for the island which was also available on internet radio and relayed in Ascension Island. The station was not government funded. It was launched in January 2005 and closed on 21 December 2012. It broadcast news, features and music in collaboration with its sister newspaper, the St Helena Independent (which continues).

What date was Saint FM radio launched?

January 2005

What date was Saint FM radio closed?

21 December 2012

Which newspaper is the sister company of Saint FM radio?

St Helena Independent


Saint FM Community Radio took over the radio channels vacated by Saint FM and launched on 10 March 2013. The station operates as a limited-by-guarantee company owned by its members and is registered as a fund-raising Association. Membership is open to everyone, and grants access to a live audio stream.

Which company took over the channels vacated by Saint FM?

Saint FM Community Radio

What date did Saint FM Community Radio launch?

10 March 2013

What kind of people can join Saint Fm Radio Community?

everyone


St Helena Online is a not-for-profit internet news service run from the UK by a former print and BBC journalist, working in partnership with Saint FM and the St Helena Independent.

Who runs Saint Helena online?

a former print and BBC journalist

Who is partnered with Saint Helena online?

Saint FM and the St Helena Independent


Sure South Atlantic Ltd ("Sure") offers television for the island via 17 analogue terrestrial UHF channels, offering a mix of British, US, and South African programming. The channels are from DSTV and include Mnet, SuperSport and BBC channels. The feed signal, from MultiChoice DStv in South Africa, is received by a satellite dish at Bryant's Beacon from Intelsat 7 in the Ku band.

What does Sure South Atlantic LTD offer?

television

How many analogue terrestrial UHF channels does Sure South Atlantic LTD have?

What is the feed signal of Sure South Atlantic received by?

a satellite dish


SURE provide the telecommunications service in the territory through a digital copper-based telephone network including ADSL-broadband service. In August 2011 the first fibre-optic link has been installed on the island, which connects the television receive antennas at Bryant's Beacon to the Cable & Wireless Technical Centre in the Briars.

SURE provides what kind of service to the territory?

telecommunications

What kind of network does SURE provide it's service from?

digital copper-based telephone network

When was the first fibre-optic network installed?

August 2011


A satellite ground station with a 7.6-metre (25 ft) satellite dish installed in 1989 at The Briars is the only international connection providing satellite links through Intelsat 707 to Ascension island and the United Kingdom. Since all international telephone and internet communications are relying on this single satellite link both internet and telephone service are subject to sun outages.

How big is the satellite dish at the satellite ground station in feet?

When was the satellite dish installed?

Where was the satellite dish installed?

The Briars

Both telephone and internet services are subject to what?

sun outages


Saint Helena has the international calling code +290 which, since 2006, Tristan da Cunha shares. Saint Helena telephone numbers changed from 4 to 5 digits on 1 October 2013 by being prefixed with the digit "2", i.e. 2xxxx, with the range 5xxxx being reserved for mobile numbering, and 8xxx being used for Tristan da Cunha numbers (these still shown as 4 digits).

What is the international calling code for Saint Helena?

Who shares the calling code +290 with Saint Helena?

Tristan da Cunha

How many digits did Saint Helena change their phone numbers to?

When did Saint Helena change the amount of digits in their phone numbers?

1 October 2013

What digit are Saint Helena phone numbers prefixed with?


Saint Helena has a 10/3.6 Mbit/s internet link via Intelsat 707 provided by SURE. Serving a population of more than 4,000, this single satellite link is considered inadequate in terms of bandwidth.

What speed is Saint Helena internet access?

10/3.6 Mbit/s

What is the internet service provided through?

Intelsat 707

Who provides the internet service in Saint Helena?

SURE

What kind of population does SURE service?

more than 4,000

How many satellites provide the link to the internet?


ADSL-broadband service is provided with maximum speeds of up to 1536 KBit/s downstream and 512 KBit/s upstream offered on contract levels from lite £16 per month to gold+ at £190 per month. There are a few public WiFi hotspots in Jamestown, which are also being operated by SURE (formerly Cable & Wireless).

What kind of broadband service is provided on the island?

ADSL

What is the maximum speed of the broadband service?

1536 KBit/s downstream and 512 KBit/s upstream

What is the lite price of the broadband service?

£16 per month

What is the gold price of the broadband service?

£190 per month

What location has a few public wifi spots available to the public?

Jamestown


The South Atlantic Express, a 10,000 km (6,214 mi) submarine communications cable connecting Africa to South America, run by the undersea fibre optic provider eFive, will pass St Helena relatively closely. There were no plans to land the cable and install a landing station ashore, which could supply St Helena's population with sufficient bandwidth to fully leverage the benefits of today's Information Society. In January 2012, a group of supporters petitioned the UK government to meet the cost of landing the cable at St Helena. On 6 October 2012, eFive agreed to reroute the cable through St. Helena after a successful lobbying campaign by A Human Right, a San Francisco-based NGA working on initiatives to ensure all people are connected to the Internet. Islanders have sought the assistance of the UK Department for International Development and Foreign and Commonwealth Office in funding the £10m required to bridge the connection from a local junction box on the cable to the island. The UK Government have announced that a review of the island's economy would be required before such funding would be agreed to.

How long is the South Atlantic Express in miles?

Who runs the South Atlantic Express?

eFive

On what date did eFive announce they would reroute the cable through Saint Helena?

6 October 2012

Who lobbied for the cable reroute into South Helena?

A Human Right


The island has two local newspapers, both of which are available on the Internet. The St Helena Independent has been published since November 2005. The Sentinel newspaper was introduced in 2012.

How many local newspapers does the island have?

two

Where are both newspapers available?

the Internet

Since when has the St Helena Independent been published?

November 2005

When was the Sentinel Newspaper introduced?


Education is free and compulsory between the ages of 5 and 16  The island has three primary schools for students of age 4 to 11: Harford, Pilling, and St Paul’s. Prince Andrew School provides secondary education for students aged 11 to 18. At the beginning of the academic year 2009-10, 230 students were enrolled in primary school and 286 in secondary school.

How many primary schools does the island have?

What are the 3 primary schools called?

Harford, Pilling, and St Paul’s

What is the name of the secondary school for the island?

Prince Andrew School

How many students were enrolled in primary school in 2010?


The Education and Employment Directorate also offers programmes for students with special needs, vocational training, adult education, evening classes, and distance learning. The island has a public library (the oldest in the Southern Hemisphere) and a mobile library service which operates weekly rural areas.

When does the mobile library service operate?

weekly

Who provides programs to students with special needs?

The Education and Employment Directorate


The UK national curriculum is adapted for local use. A range of qualifications are offered – from GCSE, A/S and A2, to Level 3 Diplomas and VRQ qualifications:

What curriculum does the island adapt?

The UK national curriculum

What are the qualifications offered?

GCSE, A/S and A2, to Level 3 Diplomas and VRQ qualifications


Sports played on the island include football, cricket, volleyball, tennis, golf, motocross, shooting sports and yachting. Saint Helena has sent teams to a number of Commonwealth Games. Saint Helena is a member of the International Island Games Association. The Saint Helena cricket team made its debut in international cricket in Division Three of the African region of the World Cricket League in 2011.

Saint Helena is a member of what kind of association?

International Island Games Association

Where did the Saint Helena cricket team make it's debut in international cricket?

Division Three of the African region of the World Cricket League

When did the Saint Helena cricket team make it's debut in international cricket?


The Governor's Cup is a yacht race between Cape Town and Saint Helena island, held every two years in December/January; the most recent event was in December 2010. In Jamestown a timed run takes place up Jacob's Ladder every year, with people coming from all over the world to take part.

Where does the Governor's cup take place?

between Cape Town and Saint Helena island,

What months does the Governor's cup take place?

December/January

When did the most recent Governor's cup take place?

December 2010


There are scouting and guiding groups on Saint Helena and Ascension Island. Scouting was established on Saint Helena island in 1912. Lord and Lady Baden-Powell visited the Scouts on Saint Helena on the return from their 1937 tour of Africa. The visit is described in Lord Baden-Powell's book entitled African Adventures.

What kind of groups are on Saint Helena and Ascension Island?

scouting and guiding

When was Scouting established on Saint Helena?

Who visited the scouts on their return from the tour of Africa in 1937?

Lord and Lady Baden-Powell

What book describes Lord and Lady Baden-Powel's visit?

African Adventures


In phonetics, aspiration is the strong burst of breath that accompanies either the release or, in the case of preaspiration, the closure of some obstruents. In English, aspirated consonants are allophones in complementary distribution with their unaspirated counterparts, but in some other languages, notably most Indian and East Asian languages, the difference is contrastive.

Aspiration and preaspiration are used in what?

phonetics

Aspirated consonants are what in English?

allophones

What are two language types where the difference is contrastive?

Indian and East Asian

What creates a strong burst of breath?

I'm not sure.

What are aspirated consonants in the Asian language?

I'm not sure.

Allophones are similar in what two languages?

I'm not sure.

What accompanies the opening of some obstruents?

I'm not sure.

What uses a weak burst of breath?

I'm not sure.


To feel or see the difference between aspirated and unaspirated sounds, one can put a hand or a lit candle in front of one's mouth, and say pin [pʰɪn] and then spin [spɪn]. One should either feel a puff of air or see a flicker of the candle flame with pin that one does not get with spin. In most dialects of English, the initial consonant is aspirated in pin and unaspirated in spin.

With what word should you see a candle flicker or feel a puff of air?

pin

In English the first consonant in "pin" is what?

aspirated

When should one put a hand or a lit candle in front of one's eyes?

I'm not sure.

In what dialect would the initial consonant be unaspriated in pin and aspirated in spin?

I'm not sure.

Which word would be aspirated in most English dialects?

I'm not sure.

What would you see when you use your hand to see the difference between aspirated and unaspirated sounds?

I'm not sure.

What would you do to see the similarities between aspirated and unaspirated sounds?

I'm not sure.


In the International Phonetic Alphabet (IPA), aspirated consonants are written using the symbols for voiceless consonants followed by the aspiration modifier letter ⟨◌ʰ⟩, a superscript form of the symbol for the voiceless glottal fricative ⟨h⟩. For instance, ⟨p⟩ represents the voiceless bilabial stop, and ⟨pʰ⟩ represents the aspirated bilabial stop.

What does IPA stand for?

International Phonetic Alphabet

Written IPA consonants use symbols for what?

voiceless consonants

What modifier indicates a voiceless bilabial stop?

p

pʰ represents what?

aspirated bilabial stop

What is considered an unaspirated consonant?

I'm not sure.

Aspiration modifiers are represented by what?

I'm not sure.

Voiceless consonants are prefaced by what?

I'm not sure.

The voiced glottal fricative is indicated by what letter?

I'm not sure.

The unaspirated bilabial stop is represented by what letter?

I'm not sure.


Voiced consonants are seldom actually aspirated. Symbols for voiced consonants followed by ⟨◌ʰ⟩, such as ⟨bʰ⟩, typically represent consonants with breathy voiced release (see below). In the grammatical tradition of Sanskrit, aspirated consonants are called voiceless aspirated, and breathy-voiced consonants are called voiced aspirated.

What is not often aspirated?

Voiced consonants

The symbol followed by bʰ would likely mean the consonant has what type of release?

breathy

Voiced aspirated consonants are what type?

breathy-voiced

Voiced symbols are seldom what?

I'm not sure.

Symbols for voiceless consonants are typical in what language?

I'm not sure.

Unaspirated consonants are called what?

I'm not sure.

Symbols for voiced releases typically represent what?

I'm not sure.

Breathy-voiced aspirated consonants are called what?

I'm not sure.


There are no dedicated IPA symbols for degrees of aspiration and typically only two degrees are marked: unaspirated ⟨k⟩ and aspirated ⟨kʰ⟩. An old symbol for light aspiration was ⟨ʻ⟩, but this is now obsolete. The aspiration modifier letter may be doubled to indicate especially strong or long aspiration. Hence, the two degrees of aspiration in Korean stops are sometimes transcribed ⟨kʰ kʰʰ⟩ or ⟨kʻ⟩ and ⟨kʰ⟩, but they are usually transcribed [k] and [kʰ], with the details of voice-onset time given numerically.

There are no IPA symbols for what?

degrees of aspiration

What may be doubled to indicate a long aspiration?

aspiration modifier

What language, according to the text, may need double stops to indicate aspiration length?

Korean

How are voice-onset time details usually presented?

numerically

Which two IPA symbols are marked?

I'm not sure.

The two degrees of aspiration in English stops are transcribed as what?

I'm not sure.

The details of voice-onset symbols are given how?

I'm not sure.

Which old letter for light aspiration is now obsolete?

I'm not sure.

The aspiration modifier letter may be tripled to indicate what?

I'm not sure.


Preaspirated consonants are marked by placing the aspiration modifier letter before the consonant symbol: ⟨ʰp⟩ represents the preaspirated bilabial stop.

A preaspirated consonant is marked how?

placing the aspiration modifier letter before the consonant symbol

What represents a preaspirated bilabial stop?

⟨ʰp⟩

Preaspirated symbols are marked how?

I'm not sure.

What represents the unaspirated bilabial stop?

I'm not sure.

What represents the aspiration modifier letter?

I'm not sure.

What represents the preaspirated bilabial start?

I'm not sure.

Unaspirated consonants are marked how?

I'm not sure.


Unaspirated or tenuis consonants are occasionally marked with the modifier letter for unaspiration ⟨◌˭⟩, a superscript equal sign: ⟨t˭⟩. Usually, however, unaspirated consonants are left unmarked: ⟨t⟩.

How are unaspirated or tenuis consonants sometimes marked for unaspiration?

with the modifier letter

What is the superscript equal sign?

⟨t˭⟩

Most often, unaspirated consonants are what?

left unmarked

How are unaspirated consonants left unmarked?

⟨t⟩

Aspirated or tenuis consonants are occasionally marked how?

I'm not sure.

How are aspirated consonants marked?

I'm not sure.

How are aspirated consonants usually left?

I'm not sure.

What is occasionally marked with the modifier letter for aspiration?

I'm not sure.

Unspirated or tenuis symbols are occasionally marked with which letter?

I'm not sure.


Voiceless consonants are produced with the vocal folds open (spread) and not vibrating, and voiced consonants are produced when the vocal folds are fractionally closed and vibrating (modal voice). Voiceless aspiration occurs when the vocal cords remain open after a consonant is released. An easy way to measure this is by noting the consonant's voice-onset time, as the voicing of a following vowel cannot begin until the vocal cords close.

What is created when the vocal folds are spread and do not vibrate?

Voiceless consonants

What is created when vocal folds are slightly closed and vibrate?

voiced consonants

What is it called when a person's vocal cords stay open after a consonant?

Voiceless aspiration

Voiced consonants are produced when what opens?

I'm not sure.

How would you measure voiced aspiration?

I'm not sure.

When the vocal folds are vibrating, what is produced?

I'm not sure.

What can not begin until after the vocal cords open?

I'm not sure.

What is produced when the vocal folds are open and vibrating?

I'm not sure.


Phonetically in some languages, such as Navajo, aspiration of stops tends to be realised as voiceless velar airflow; aspiration of affricates is realised as an extended length of the frication.

Aspiration of stops is seen as voiceless velar airflow in some languages, such as what?

Navajo

In Navajo, the aspiration of affricates can be seen as what?

an extended length of the frication

What is realized as an extended length of the airflow?

I'm not sure.

In what language does the unaspiration of stops tend to be realized as voiceless velar airflow?

I'm not sure.

What is realized as voiced velar airflow?

I'm not sure.

In what language does voiceless velar airflow not exist?

I'm not sure.

Aspiration of airflow is realized as what?

I'm not sure.


Aspirated consonants are not always followed by vowels or other voiced sounds. For example, in Eastern Armenian, aspiration is contrastive even word-finally, and aspirated consonants occur in consonant clusters. In Wahgi, consonants are aspirated only in final position.

In Eastern Armenian, aspirated consonants occur in what?

consonant clusters

Where are consonants aspirated in just the final position?

Wahgi

Unaspirated consonants are not always followed by what?

I'm not sure.

In what language is unaspiration contrastive?

I'm not sure.

In what language are consonants aspirated only in start position?

I'm not sure.

What occurs in sound clusters?

I'm not sure.

What is not always followed by vowels or unvoiced sounds?

I'm not sure.


Armenian and Cantonese have aspiration that lasts about as long as English aspirated stops, in addition to unaspirated stops. Korean has lightly aspirated stops that fall between the Armenian and Cantonese unaspirated and aspirated stops as well as strongly aspirated stops whose aspiration lasts longer than that of Armenian or Cantonese. (See voice-onset time.)

As well as lasting as long as an English aspirated stop, the Armenian and Cantonese aspiration lasts as long as what?

unaspirated stops

What languages have aspiration that lasts about as long as Korean aspirated stops?

I'm not sure.

Whose aspiration lasts longer than that of Armenian or Korean?

I'm not sure.

Whose stops are shorter than that of Armenian or Cantonese?

I'm not sure.

Korean has what kind of unaspirated stops?

I'm not sure.

Armenian unaspirated stops last longer than whose?

I'm not sure.


Aspiration varies with place of articulation. The Spanish voiceless stops /p t k/ have voice-onset times (VOTs) of about 5, 10, and 30 milliseconds, whereas English aspirated /p t k/ have VOTs of about 60, 70, and 80 ms. Voice-onset time in Korean has been measured at 20, 25, and 50 ms for /p t k/ and 90, 95, and 125 for /pʰ tʰ kʰ/.

Aspiration alters with what?

place of articulation

Voice-onset times in Armenian measure at 20, 25, and what?

I'm not sure.

Unaspiration varies with what?

I'm not sure.

Which language measures at 60, 70, and 50 ms?

I'm not sure.

The Spanish voice-closing times are what?

I'm not sure.

The Spanish voiced stops are?

I'm not sure.


When aspirated consonants are doubled or geminated, the stop is held longer and then has an aspirated release. An aspirated affricate consists of a stop, fricative, and aspirated release. A doubled aspirated affricate has a longer hold in the stop portion and then has a release consisting of the fricative and aspiration.

What happens when an aspirated consonant is doubled or geminated?

the stop is held longer and then has an aspirated release.

What is comprised of a stop, fricative, and aspirated release?

An aspirated affricate

What happens when aspirated consonants are tripled or germinated?

I'm not sure.

What has a release of the fricative and unaspiration?

I'm not sure.

An unaspirated consonant consists of what?

I'm not sure.

What consists of a stop, fricative, and unaspirated release?

I'm not sure.

A tripled aspirated affricate has a longer what?

I'm not sure.


Icelandic and Faroese have preaspirated [ʰp ʰt ʰk]; some scholars interpret these as consonant clusters as well. In Icelandic, preaspirated stops contrast with double stops and single stops:

What two languages mentioned have have preaspirated [ʰp ʰt ʰk]?

Icelandic and Faroese

What do scholars say the preaspirated [ʰp ʰt ʰk] are too?

consonant clusters

What do preaspirated stops contrast with in Icelandic?

double stops and single stops

What stops contrast with triple and single stops?

I'm not sure.

Icelandic and English have preaspirated what?

I'm not sure.

Aspirated stops contrast with what?

I'm not sure.

In Faroese, preaspirated stops contrast with what?

I'm not sure.

Symbol clusters exists in which two languages?

I'm not sure.


Preaspirated stops also occur in most Sami languages; for example, in North Sami, the unvoiced stop and affricate phonemes /p/, /t/, /ts/, /tʃ/, /k/ are pronounced preaspirated ([ʰp], [ʰt] [ʰts], [ʰtʃ], [ʰk]) when they occur in medial or final position.

The Sami tongue also has what?

Preaspirated stops

Which Sami tongue has unvoiced stop and affricate phonemes pronounced preaspirated?

North Sami

Unaspirated stops occur in which languages?

I'm not sure.

What occurs in the medial or start position?

I'm not sure.

The voiced stop and affricate phonemes occur in what position?

I'm not sure.

What are pronounced unaspirated?

I'm not sure.

In South Sami what are pronounced preaspirated?

I'm not sure.


Although most aspirated obstruents in the world's language are stops and affricates, aspirated fricatives such as [sʰ], [fʰ] or [ɕʰ] have been documented in Korean, in a few Tibeto-Burman languages, in some Oto-Manguean languages, and in the Siouan language Ofo. Some languages, such as Choni Tibetan, have up to four contrastive aspirated fricatives [sʰ] [ɕʰ], [ʂʰ] and [xʰ].

How many contrastive aspirated fricatives does Choni Tibetan have?

up to four

Unaspirated fricatives have been documented in which language?

I'm not sure.

Which language has up to five contrastive aspirated fricatives?

I'm not sure.

Most unaspirated obstruents are what?

I'm not sure.

The Siouan language Ofo has how many contrastive aspirated fricatives?

I'm not sure.

Choni Tibetan has how many unaspirated fricatives?

I'm not sure.


True aspirated voiced consonants, as opposed to murmured (breathy-voice) consonants such as the [bʱ], [dʱ], [ɡʱ] that are common in the languages of India, are extremely rare. They have been documented in Kelabit Taa, and the Kx'a languages. Reported aspirated voiced stops, affricates and clicks are [b͡pʰ, d͡tʰ, d͡tsʰ, d͡tʃʰ, ɡ͡kʰ, ɢ͡qʰ, ᶢʘʰ, ᶢǀʰ, ᶢǁʰ, ᶢǃʰ, ᶢǂʰ].

Indian languages commonly have murmured consonants instead of what?

True aspirated voiced consonants

True aspirated consonants are considered what?

rare

True aspirated consonants have been found in Kelabit Taa and what else?

Kx'a languages

Are truly unaspirated voiceless consonants common or rare?

I'm not sure.

What is common in the language of English?

I'm not sure.

Murmured consonants are uncommon in which language of which country?

I'm not sure.

What has been documented in Kelabit Taa, and the Kx'a languages?

I'm not sure.

True aspirated voice consonants are common in which country?

I'm not sure.


Aspiration has varying significance in different languages. It is either allophonic or phonemic, and may be analyzed as an underlying consonant cluster.

What has a different significance in various languages?

Aspiration

What two forms can aspiration be in?

allophonic or phonemic

What may be analyzed as an underlying symbol cluster?

I'm not sure.

Aspiration can differ in which two languages?

I'm not sure.

Unaspiration has varying significance in what?

I'm not sure.

What may be analyzed as an underlying phonemic cluster?

I'm not sure.

What is either allophonic or a cluster?

I'm not sure.


In some languages, such as English, aspiration is allophonic. Stops are distinguished primarily by voicing, and voiceless stops are sometimes aspirated, while voiced stops are usually unaspirated.

Aspiration is what, in English and some other languages?

allophonic

How are stops distinguished?

voicing

Voiceless stops are at times what?

aspirated

Voiced stops are most often what?

unaspirated

In what language in unaspiration allophonic?

I'm not sure.

Voiceless languages are sometimes what?

I'm not sure.

Symbols are distinguished primarily by what?

I'm not sure.

Voiced breaths are usually what?

I'm not sure.

What are sometimes allophonic?

I'm not sure.


They are unaspirated for almost all speakers when immediately following word-initial s, as in spill, still, skill. After an s elsewhere in a word they are normally unaspirated as well, except sometimes in compound words. When the consonants in a cluster like st are analyzed as belonging to different morphemes (heteromorphemic) the stop is aspirated, but when they are analyzed as belonging to one morpheme the stop is unaspirated.[citation needed] For instance, distend has unaspirated [t] since it is not analyzed as two morphemes, but distaste has an aspirated middle [tʰ] because it is analyzed as dis- + taste and the word taste has an aspirated initial t.

When following a word such as spill, they are what for most speakers?

unaspirated

If the letter s is a different place in the word, it is typical unaspirated unless the word is what?

compound words

If there is a cluster such as st and it belongs to different morphemes, the stop is what?

aspirated

If the st belongs to one morpheme, then the stop is what?

unaspirated

What is unaspirated since it is not analyzed as three morphemes?

I'm not sure.

What word-initial is aspirated for almost all speakers?

I'm not sure.

When is the consonant unaspirated?

I'm not sure.

Distaste has an unaspirated middle why?

I'm not sure.

After a k elsewhere in a word they are normally what?

I'm not sure.


In many languages, such as Armenian, Korean, Thai, Indo-Aryan languages, Dravidian languages, Icelandic, Ancient Greek, and the varieties of Chinese, tenuis and aspirated consonants are phonemic. Unaspirated consonants like [p˭ s˭] and aspirated consonants like [pʰ ʰp sʰ] are separate phonemes, and words are distinguished by whether they have one or the other.

In languages like Thai and Icelandic, tenuis and aspirated consonants are what?

phonemic

[p˭ s˭] and [pʰ ʰp sʰ] are separate what?

phonemes

In the Armenian language, tenuis and unaspirated stops are what?

I'm not sure.

What makes up combined phonemes?

I'm not sure.

Sentences are distinguished by what?

I'm not sure.

In the English language, tenuis and aspirated consonants are what?

I'm not sure.

An example of an unaspirated stop is?

I'm not sure.


In Danish and most southern varieties of German, the "lenis" consonants transcribed for historical reasons as ⟨b d ɡ⟩ are distinguished from their fortis counterparts ⟨p t k⟩, mainly in their lack of aspiration.

How are lenis consonants distinguished from fortis consonants?

their lack of aspiration

If the lenis are ⟨b d ɡ⟩, what are the fortis counterparts?

⟨p t k⟩

What is often transcribed for numerical reasons?

I'm not sure.

In English, "lenis" consonants are know as what?

I'm not sure.

The "lenis" consonants are distinguished from their modern counterparts by what?

I'm not sure.

Fortis counterparts are known as what in the Spanish language?

I'm not sure.

Fortis counterparts are translated as what in the Chinese language?

I'm not sure.


Standard Chinese (Mandarin) has stops and affricates distinguished by aspiration: for instance, /t tʰ/, /t͡s t͡sʰ/. In pinyin, tenuis stops are written with letters that represent voiced consonants in English, and aspirated stops with letters that represent voiceless consonants. Thus d represents /t/, and t represents /tʰ/.

Mandarin has stops and affricates that are distinguished by what?

aspiration

Tenuis stops have letters that are representative of English voiced consonant in what?

pinyin

What kind of stops in pinyin are written with letters that representative of voiceless consonants?

aspirated stops

The English language has stops and affricates distinguished by what?

I'm not sure.

In pinyin, tenuis consonants are written how?

I'm not sure.

In pinyin, unaspirated stops are written how?

I'm not sure.

What is written with letter that represent voiced consonants?

I'm not sure.

What represents d?

I'm not sure.


Wu Chinese has a three-way distinction in stops and affricates: /p pʰ b/. In addition to aspirated and unaspirated consonants, there is a series of muddy consonants, like /b/. These are pronounced with slack or breathy voice: that is, they are weakly voiced. Muddy consonants as initial cause a syllable to be pronounced with low pitch or light (陽 yáng) tone.

What has a three-way distinction in regards to stops and affricates?

Wu Chinese

What is the actual distinction for Wu Chinese?

/p pʰ b/

What is /b/ representative of, in addition to aspirated and unaspirated consonants?

Muddy consonants

What kind of voice are muddy consonants pronounced with?

slack or breathy

Wu Chinese has a four-way distinction in what?

I'm not sure.

What is strongly voiced?

I'm not sure.

What causes a syllable to be pronounced with high pitch or light tone?

I'm not sure.

What is an example of a breathy consonant?

I'm not sure.

What causes a stop to be pronounced with low pitch or light tone?

I'm not sure.


Many Indo-Aryan languages have aspirated stops. Sanskrit, Hindi, Bengali, Marathi, and Gujarati have a four-way distinction in stops: voiceless, aspirated, voiced, and breathy-voiced or voiced aspirated, such as /p pʰ b bʱ/. Punjabi has lost breathy-voiced consonants, which resulted in a tone system, and therefore has a distinction between voiceless, aspirated, and voiced: /p pʰ b/.

How many distinctions in stops do languages like Bengali and Hindi have?

four

What is another term for voice-aspirated?

breathy-voiced

Which distinction has Punjabi lost?

breathy-voiced consonants

What languages have unaspirated stops?

I'm not sure.

Sanskrit has a three-way distinction in what?

I'm not sure.

What has gained breathy-voiced consonants?

I'm not sure.

What happened to result in a toneless system?

I'm not sure.

What is an example of a two-way distinction in stops?

I'm not sure.


Some of the Dravidian languages, such as Telugu, Tamil, Malayalam, and Kannada, have a distinction between voiced and voiceless, aspirated and unaspirated only in loanwords from Indo-Aryan languages. In native Dravidian words, there is no distinction between these categories and stops are underspecified for voicing and aspiration.

Telegu, Kannada and others are considered to be some of the what languages?

Dravidian

What has no distinction between the categories  of voiced, voiceless, aspirated and unaspirated?

native Dravidian words

In native English words, there is no distinction between what?

I'm not sure.

What is used only in loanwords from Spanish languages?

I'm not sure.

What is underspecified for voicing and unaspiratoin?

I'm not sure.

There are many category distinctions in what language?

I'm not sure.

All of the Dravidian languages have a distinction between what?

I'm not sure.


Western Armenian has a two-way distinction between aspirated and voiced: /tʰ d/. Western Armenian aspirated /tʰ/ corresponds to Eastern Armenian aspirated /tʰ/ and voiced /d/, and Western voiced /d/ corresponds to Eastern voiceless /t/.

What language has two-way distinctions between aspirated and voiced?

Western Armenian

Western Armenian /tʰ/ compares to eastern Armenian /tʰ/ and what?

/d/

The Western Armenian voiced /d/ compares to the Eastern Armenian voiceless what?

/t/

Western Armenian has a three-way distinction between what?

I'm not sure.

Western Armenian aspirated corresponds to Eastern American what?

I'm not sure.

Western voiced /d/ corresponds to Eastern voiced what?

I'm not sure.

Eastern Armenian has a two-way distinction between what?

I'm not sure.

Western voiceless /d/ corresponds to what?

I'm not sure.


Some forms of Greek before the Koine Greek period are reconstructed as having aspirated stops. The Classical Attic dialect of Ancient Greek had a three-way distinction in stops like Eastern Armenian: /t tʰ d/. These stops were called ψιλά, δασέα, μέσα "thin, thick, middle" by Koine Greek grammarians.

Early Greek (before Koine) have been redone with what?

aspirated stops.

What Greek dialect had three-way stop distinction like Eastern Armenian?

Classical Attic

Who referred to the Classical Attic dialect stops by the three distinctions?

Greek grammarians

A two-way distinction in stops was called what?

I'm not sure.

Some forms of English are reconstructed as what?

I'm not sure.

Which Armenian language had a two-way distinction in stops?

I'm not sure.

The Classical Arctic dialect belonged to which country?

I'm not sure.

Which languages are reconstructed as having unaspirated stops?

I'm not sure.


There were aspirated stops at three places of articulation: labial, coronal, and velar /pʰ tʰ kʰ/. Earlier Greek, represented by Mycenaean Greek, likely had a labialized velar aspirated stop /kʷʰ/, which later became labial, coronal, or velar depending on dialect and phonetic environment.

What is the representation for the three places of articulation?

/pʰ tʰ kʰ/

Earlier Greek was represented by what?

Mycenaean Greek

Whether a stop was labial, coronal or velar depended on what two things?

dialect and phonetic environment

Unaspirated stops were at which three places of articulation?

I'm not sure.

Early Greece was represented by what?

I'm not sure.

What likely had a velar unaspirated stop?

I'm not sure.

The three places of articulation are the labial, cortical and what?

I'm not sure.

The labialized velar unaspirated stop is represented by what?

I'm not sure.


The other Ancient Greek dialects, Ionic, Doric, Aeolic, and Arcadocypriot, likely had the same three-way distinction at one point, but Doric seems to have had a fricative in place of /tʰ/ in the Classical period, and the Ionic and Aeolic dialects sometimes lost aspiration (psilosis).

Dialects such as Aeolic and Doric had how many distinctions that were the same at one point in time?

three

Which two dialects lost aspiration at times?

Ionic and Aeolic

Rather than /tʰ/, what did the Doric dialect have in place during the Classical period?

fricative

What ancient dialects had the same two-way distinction at one point?

I'm not sure.

What dialect had a fricative in the Modern period?

I'm not sure.

Which four dialects sometimes lost aspiration?

I'm not sure.

Which two dialects sometime gained aspiration?

I'm not sure.

What was gained aspiration called?

I'm not sure.


Later, during the Koine Greek period, the aspirated and voiceless stops /tʰ d/ of Attic Greek lenited to voiceless and voiced fricatives, yielding /θ ð/ in Medieval and Modern Greek.

Attic Greek lenited to what?

voiceless and voiced fricatives

The lenited Attic Greek yielded /θ ð/ in what periods?

Medieval and Modern Greek

Arctic Greek yielded what other versions of the Greek language?

I'm not sure.

During what period did unaspirated and voiceless stops lenited to voiceless and voiced fricatives?

I'm not sure.

What represents unaspirated and voiceless stops?

I'm not sure.

Arctic Greek lenited to what?

I'm not sure.


The term aspiration sometimes refers to the sound change of debuccalization, in which a consonant is lenited (weakened) to become a glottal stop or fricative [ʔ h ɦ].

Aspiration may refer to a sound change of what?

debuccalization

Debuccalization is when consonants are weakened to become what?

glottal stop or fricative

What is another term for a consonant being weakened?

lenited

The term unaspiration sometimes refers to what?

I'm not sure.

When is a consonant strengthened to become a glottal stop or fricative?

I'm not sure.

What is sometime referred to as the vocal change of debuccalization?

I'm not sure.

What sometimes becomes a global stop or fricative?

I'm not sure.

When a sound is lenited it becomes what?

I'm not sure.


So-called voiced aspirated consonants are nearly always pronounced instead with breathy voice, a type of phonation or vibration of the vocal folds. The modifier letter ⟨◌ʰ⟩ after a voiced consonant actually represents a breathy-voiced or murmured dental stop, as with the "voiced aspirated" bilabial stop ⟨bʰ⟩ in the Indo-Aryan languages. This consonant is therefore more accurately transcribed as ⟨b̤⟩, with the diacritic for breathy voice, or with the modifier letter ⟨bʱ⟩, a superscript form of the symbol for the voiced glottal fricative ⟨ɦ⟩.

What is breathy voice?

a type of phonation or vibration of the vocal folds

The ⟨bʰ⟩ in the Indo-Aryan languages is better transcribed how for breathy voice?

⟨b̤⟩, with the diacritic

What is the superscript form of the symbol for the voiceless glottal fricative?

I'm not sure.

Unaspirated consonants are nearly always pronouced how?

I'm not sure.

What causes a murmured vibration of the vocal cords?

I'm not sure.

What represents a strong voiced or breathy dental stop?

I'm not sure.

What represents the "voice aspirated" bilabial stop in the English language?

I'm not sure.


Some linguists restrict the double-dot subscript ⟨◌̤⟩ to murmured sonorants, such as vowels and nasals, which are murmured throughout their duration, and use the superscript hook-aitch ⟨◌ʱ⟩ for the breathy-voiced release of obstruents.

What do some linguists restrict the double-dot subscript ⟨◌̤⟩ to?

murmured sonorants

What are, according to the text, murmured for their duration?

vowels and nasals

What uses the ⟨◌ʱ⟩?

breathy-voiced release of obstruents.

Some linguists restrict what to loud sonorants?

I'm not sure.

What are murmured thought part of their duration?

I'm not sure.

What represents the double-dot hook-aitch?

I'm not sure.

What is used for the loud-voiced release of obstruents?

I'm not sure.

All linguists restrict the double-dot subscript to what?

I'm not sure.


Hydrogen is a chemical element with chemical symbol H and atomic number 1. With an atomic weight of 7000100794000000000♠1.00794 u, hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.[note 1] Non-remnant stars are mainly composed of hydrogen in its plasma state. The most common isotope of hydrogen, termed protium (name rarely used, symbol 1H), has one proton and no neutrons.

What is hydrogens chemical symbol?

H

What is the atomic number used for hydrogen?

What is the atomic weight for hydrogen?

7000100794000000000♠1.00794 u

What element is considered the lightest?

Hydrogen


The universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic gas with the molecular formula H2. Since hydrogen readily forms covalent compounds with most non-metallic elements, most of the hydrogen on Earth exists in molecular forms such as in the form of water or organic compounds. Hydrogen plays a particularly important role in acid–base reactions as many acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a negative charge (i.e., anion) when it is known as a hydride, or as a positively charged (i.e., cation) species denoted by the symbol H+. The hydrogen cation is written as though composed of a bare proton, but in reality, hydrogen cations in ionic compounds are always more complex species than that would suggest. As the only neutral atom for which the Schrödinger equation can be solved analytically, study of the energetics and bonding of the hydrogen atom has played a key role in the development of quantum mechanics.

What form can you find hydrogen is on Earth?

molecular

What is the molecular make-up of hydrogen?

What are three properties of hydrogen at normal temperature and normal pressure?

colorless, odorless, tasteless

What charge does hydrogen display in ionic compounds when it is called a hydride?

negative

What field of study has hydrogen and it's properties played a key role in development?

quantum mechanics


Hydrogen gas was first artificially produced in the early 16th century, via the mixing of metals with acids. In 1766–81, Henry Cavendish was the first to recognize that hydrogen gas was a discrete substance, and that it produces water when burned, a property which later gave it its name: in Greek, hydrogen means "water-former".

When was hydrogen gas artificially produced for the first time?

early 16th century

Who first recognized that hydrogen was a discrete substance?

Henry Cavendish

When it is burned what does hydrogen make?

water

What is the Greek translation for hydrogen?

water-former


Industrial production is mainly from the steam reforming of natural gas, and less often from more energy-intensive hydrogen production methods like the electrolysis of water. Most hydrogen is employed near its production site, with the two largest uses being fossil fuel processing (e.g., hydrocracking) and ammonia production, mostly for the fertilizer market. Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks.

What market primarily uses ammonia production?

the fertilizer market

Name a process that uses fossil fuels along with hydrogen.

hydrocracking


Hydrogen gas (dihydrogen or molecular hydrogen) is highly flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion for hydrogen is −286 kJ/mol:

For hydrogen what is the enthalpy of combustion?

286 kJ/mol

What are two forms of hydrogen gas?

dihydrogen or molecular hydrogen

Which element has a enthalpy of combustion at −286 kJ/mol?

Hydrogen


Hydrogen gas forms explosive mixtures with air if it is 4–74% concentrated and with chlorine if it is 5–95% concentrated. The mixtures may be ignited by spark, heat or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C (932 °F). Pure hydrogen-oxygen flames emit ultraviolet light and with high oxygen mix are nearly invisible to the naked eye, as illustrated by the faint plume of the Space Shuttle Main Engine compared to the highly visible plume of a Space Shuttle Solid Rocket Booster. The detection of a burning hydrogen leak may require a flame detector; such leaks can be very dangerous. Hydrogen flames in other conditions are blue, resembling blue natural gas flames. The destruction of the Hindenburg airship was an infamous example of hydrogen combustion; the cause is debated, but the visible orange flames were the result of a rich mixture of hydrogen to oxygen combined with carbon compounds from the airship skin.

What kind of light do hydrogen-oxygen flames make?

ultraviolet light

What caused  the Hindenburg to explode?

hydrogen combustion


H2 reacts with every oxidizing element. Hydrogen can react spontaneously and violently at room temperature with chlorine and fluorine to form the corresponding hydrogen halides, hydrogen chloride and hydrogen fluoride, which are also potentially dangerous acids.

What are two other dangerous acids?

hydrogen chloride and hydrogen fluoride

What temperature does hydrogen react with these elements?

room temperature


The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, which conceptualizes the electron as "orbiting" the proton in analogy to the Earth's orbit of the Sun. However, the electromagnetic force attracts electrons and protons to one another, while planets and celestial objects are attracted to each other by gravity. Because of the discretization of angular momentum postulated in early quantum mechanics by Bohr, the electron in the Bohr model can only occupy certain allowed distances from the proton, and therefore only certain allowed energies.

What model id used to calculate energy levels of hydrogen?

Bohr model

What attracts planets and celestial items?

gravity

What does the electromagnetic force attract to one another?

electrons and protons


A more accurate description of the hydrogen atom comes from a purely quantum mechanical treatment that uses the Schrödinger equation, Dirac equation or even the Feynman path integral formulation to calculate the probability density of the electron around the proton. The most complicated treatments allow for the small effects of special relativity and vacuum polarization. In the quantum mechanical treatment, the electron in a ground state hydrogen atom has no angular momentum at all—an illustration of how the "planetary orbit" conception of electron motion differs from reality.

What kind of movement does the electron not have in ground state?

angular


There exist two different spin isomers of hydrogen diatomic molecules that differ by the relative spin of their nuclei. In the orthohydrogen form, the spins of the two protons are parallel and form a triplet state with a molecular spin quantum number of 1 (1⁄2+1⁄2); in the parahydrogen form the spins are antiparallel and form a singlet with a molecular spin quantum number of 0 (1⁄2–1⁄2). At standard temperature and pressure, hydrogen gas contains about 25% of the para form and 75% of the ortho form, also known as the "normal form". The equilibrium ratio of orthohydrogen to parahydrogen depends on temperature, but because the ortho form is an excited state and has a higher energy than the para form, it is unstable and cannot be purified. At very low temperatures, the equilibrium state is composed almost exclusively of the para form. The liquid and gas phase thermal properties of pure parahydrogen differ significantly from those of the normal form because of differences in rotational heat capacities, as discussed more fully in spin isomers of hydrogen. The ortho/para distinction also occurs in other hydrogen-containing molecules or functional groups, such as water and methylene, but is of little significance for their thermal properties.

How many different spin isomers exist?

What state are the protons in when in the orthohydrogen form?

triplet state

When hydrogen gas is in standard temperature and pressure, what form is it considered in>

normal

What percent of para form does hydrogen gas contain?

What percent of ortho form does hydrogen gas contain?


The uncatalyzed interconversion between para and ortho H2 increases with increasing temperature; thus rapidly condensed H2 contains large quantities of the high-energy ortho form that converts to the para form very slowly. The ortho/para ratio in condensed H2 is an important consideration in the preparation and storage of liquid hydrogen: the conversion from ortho to para is exothermic and produces enough heat to evaporate some of the hydrogen liquid, leading to loss of liquefied material. Catalysts for the ortho-para interconversion, such as ferric oxide, activated carbon, platinized asbestos, rare earth metals, uranium compounds, chromic oxide, or some nickel compounds, are used during hydrogen cooling.

What are some catalysts used in hydrogen cooling

ferric oxide, activated carbon, platinized asbestos, rare earth metals, uranium compounds, chromic oxide, or some nickel compounds


While H2 is not very reactive under standard conditions, it does form compounds with most elements. Hydrogen can form compounds with elements that are more electronegative, such as halogens (e.g., F, Cl, Br, I), or oxygen; in these compounds hydrogen takes on a partial positive charge. When bonded to fluorine, oxygen, or nitrogen, hydrogen can participate in a form of medium-strength noncovalent bonding with other similar molecules between their hydrogens called hydrogen bonding, which is critical to the stability of many biological molecules. Hydrogen also forms compounds with less electronegative elements, such as the metals and metalloids, in which it takes on a partial negative charge. These compounds are often known as hydrides.

What ind of charge does hydrogen take when mixed with electronegative particles?

positive charge

What type of charge does hydrogen take when combined with a metal?

negative

When hydrogen forms with a metal, what is the compound called?

hydrides

Is H2 reactive in standard conditions?

not


Hydrogen forms a vast array of compounds with carbon called the hydrocarbons, and an even vaster array with heteroatoms that, because of their general association with living things, are called organic compounds. The study of their properties is known as organic chemistry and their study in the context of living organisms is known as biochemistry. By some definitions, "organic" compounds are only required to contain carbon. However, most of them also contain hydrogen, and because it is the carbon-hydrogen bond which gives this class of compounds most of its particular chemical characteristics, carbon-hydrogen bonds are required in some definitions of the word "organic" in chemistry. Millions of hydrocarbons are known, and they are usually formed by complicated synthetic pathways, which seldom involve elementary hydrogen.

What is the form of hydrogen and carbon called?

hydrocarbons

What is the form of hydrogen and heteroatoms called?

organic compounds

What is the study of organic compounds properties known as?

organic chemistry

What is the study of living organisms known as?

biochemistry

Organic compounds are only required to conatin what?

carbon


Compounds of hydrogen are often called hydrides, a term that is used fairly loosely. The term "hydride" suggests that the H atom has acquired a negative or anionic character, denoted H−, and is used when hydrogen forms a compound with a more electropositive element. The existence of the hydride anion, suggested by Gilbert N. Lewis in 1916 for group I and II salt-like hydrides, was demonstrated by Moers in 1920 by the electrolysis of molten lithium hydride (LiH), producing a stoichiometry quantity of hydrogen at the anode. For hydrides other than group I and II metals, the term is quite misleading, considering the low electronegativity of hydrogen. An exception in group II hydrides is BeH
2, which is polymeric. In lithium aluminium hydride, the AlH−
4 anion carries hydridic centers firmly attached to the Al(III).

 Who suggested that hydride anions existed?character does the H atom have in a hydride?

Gilbert N. Lewis

What group of hydrides is BEH considered polymeric?

group II


Although hydrides can be formed with almost all main-group elements, the number and combination of possible compounds varies widely; for example, there are over 100 binary borane hydrides known, but only one binary aluminium hydride. Binary indium hydride has not yet been identified, although larger complexes exist.

How many binary borane hydrides are known?

over 100

How many binary aluminum hydrides are there?


In inorganic chemistry, hydrides can also serve as bridging ligands that link two metal centers in a coordination complex. This function is particularly common in group 13 elements, especially in boranes (boron hydrides) and aluminium complexes, as well as in clustered carboranes.

What chemistry do hydrides serve as bridging ligands?

inorganic chemistry

What do hydrides that are bridging ligands link up?

link two metal centers

What group is briging ligands most common in?

group 13


Oxidation of hydrogen removes its electron and gives H+, which contains no electrons and a nucleus which is usually composed of one proton. That is why H+ is often called a proton. This species is central to discussion of acids. Under the Bronsted-Lowry theory, acids are proton donors, while bases are proton acceptors.

When hydrogen oxidates, what is it removing?

electrons

When hydrogen oxidates, what does it end up giving?

H+

What theory suggests that acids are proton donors?

Bronsted-Lowry


A bare proton, H+, cannot exist in solution or in ionic crystals, because of its unstoppable attraction to other atoms or molecules with electrons. Except at the high temperatures associated with plasmas, such protons cannot be removed from the electron clouds of atoms and molecules, and will remain attached to them. However, the term 'proton' is sometimes used loosely and metaphorically to refer to positively charged or cationic hydrogen attached to other species in this fashion, and as such is denoted "H+" without any implication that any single protons exist freely as a species.

What is another term for a bare proton?

H+


To avoid the implication of the naked "solvated proton" in solution, acidic aqueous solutions are sometimes considered to contain a less unlikely fictitious species, termed the "hydronium ion" (H
3O+). However, even in this case, such solvated hydrogen cations are more realistically conceived as being organized into clusters that form species closer to H
9O+
4. Other oxonium ions are found when water is in acidic solution with other solvents.

Where can oxonium ions be found?

in acidic solution with other solvents

What other term is a solvated protons referred as?

hydronium ion


Although exotic on Earth, one of the most common ions in the universe is the H+
3 ion, known as protonated molecular hydrogen or the trihydrogen cation.

What kind of molecular hydrogen is the H+3 knows as?

protonated

What kind of cation is the H+3 knowns as?

trihydrogen cation


Hydrogen has three naturally occurring isotopes, denoted 1H, 2H and 3H. Other, highly unstable nuclei (4H to 7H) have been synthesized in the laboratory but not observed in nature.

How many natural isotopes does hydrogen have>

What are the names of these isotopes?

denoted 1H, 2H and 3H

Which isotopes have unstable nuclei?

4H to 7H


Hydrogen is the only element that has different names for its isotopes in common use today. During the early study of radioactivity, various heavy radioactive isotopes were given their own names, but such names are no longer used, except for deuterium and tritium. The symbols D and T (instead of 2H and 3H) are sometimes used for deuterium and tritium, but the corresponding symbol for protium, P, is already in use for phosphorus and thus is not available for protium. In its nomenclatural guidelines, the International Union of Pure and Applied Chemistry allows any of D, T, 2H, and 3H to be used, although 2H and 3H are preferred.

Which element is the only that has different names for its isotopes?

Hydrogen

What are the only two names still used for radioactive isotopes?

deuterium and tritium

What are the symbols used for deuterium and tritium?

D and T

What does the symbol P represent?

phosphorus

What are the preferred symbols for deuterium and tritium?

2H and 3H


In 1671, Robert Boyle discovered and described the reaction between iron filings and dilute acids, which results in the production of hydrogen gas. In 1766, Henry Cavendish was the first to recognize hydrogen gas as a discrete substance, by naming the gas from a metal-acid reaction "flammable air". He speculated that "flammable air" was in fact identical to the hypothetical substance called "phlogiston" and further finding in 1781 that the gas produces water when burned. He is usually given credit for its discovery as an element. In 1783, Antoine Lavoisier gave the element the name hydrogen (from the Greek ὑδρο- hydro meaning "water" and -γενής genes meaning "creator") when he and Laplace reproduced Cavendish's finding that water is produced when hydrogen is burned.

What year was the discovery of hydrogen gas?

Who discovered Hydrogen gas?

Robert Boyle

Who recognized hydrogen gas as a discreet substance?

Henry Cavendish

In what year did Henry Cavendish recognize hydrogen gas as a discreet substance?

What does gas produce when burned?

water


Lavoisier produced hydrogen for his experiments on mass conservation by reacting a flux of steam with metallic iron through an incandescent iron tube heated in a fire. Anaerobic oxidation of iron by the protons of water at high temperature can be schematically represented by the set of following reactions:

How did Lavoisier produce hydrogen for his experiments?

reacting a flux of steam with metallic iron through an incandescent iron tube heated in a fire


Hydrogen was liquefied for the first time by James Dewar in 1898 by using regenerative cooling and his invention, the vacuum flask. He produced solid hydrogen the next year. Deuterium was discovered in December 1931 by Harold Urey, and tritium was prepared in 1934 by Ernest Rutherford, Mark Oliphant, and Paul Harteck. Heavy water, which consists of deuterium in the place of regular hydrogen, was discovered by Urey's group in 1932. François Isaac de Rivaz built the first de Rivaz engine, an internal combustion engine powered by a mixture of hydrogen and oxygen in 1806. Edward Daniel Clarke invented the hydrogen gas blowpipe in 1819. The Döbereiner's lamp and limelight were invented in 1823.

Who was the first to liquidize hydrogen?

James Dewar

In what year Did James Dewar first liquidize hydrogen?

What year was Deuterium discovered?

Who was the first to discover deuterium?

Harold Urey

What year was tritium discovered?


The first hydrogen-filled balloon was invented by Jacques Charles in 1783. Hydrogen provided the lift for the first reliable form of air-travel following the 1852 invention of the first hydrogen-lifted airship by Henri Giffard. German count Ferdinand von Zeppelin promoted the idea of rigid airships lifted by hydrogen that later were called Zeppelins; the first of which had its maiden flight in 1900. Regularly scheduled flights started in 1910 and by the outbreak of World War I in August 1914, they had carried 35,000 passengers without a serious incident. Hydrogen-lifted airships were used as observation platforms and bombers during the war.

Who invented the hydrogen filled balloons?

Jacques Charles

What year was hydrogen filled balloons invented?

what were the hydrogen lifted airships called?

Zeppelins

In what year did the first zeppelin make flight?


The first non-stop transatlantic crossing was made by the British airship R34 in 1919. Regular passenger service resumed in the 1920s and the discovery of helium reserves in the United States promised increased safety, but the U.S. government refused to sell the gas for this purpose. Therefore, H2 was used in the Hindenburg airship, which was destroyed in a midair fire over New Jersey on 6 May 1937. The incident was broadcast live on radio and filmed. Ignition of leaking hydrogen is widely assumed to be the cause, but later investigations pointed to the ignition of the aluminized fabric coating by static electricity. But the damage to hydrogen's reputation as a lifting gas was already done.

Who made the first non stop transatlantic crossing?

the British

What year was this done?

What year did the airship get destroyed?

What city was the ship over when it caught fire?

New Jersey


In the same year the first hydrogen-cooled turbogenerator went into service with gaseous hydrogen as a coolant in the rotor and the stator in 1937 at Dayton, Ohio, by the Dayton Power & Light Co.; because of the thermal conductivity of hydrogen gas, this is the most common type in its field today.

In what year did the first hydrogen cooled turbogenerator go into service?

What state is the Dayton Power and light Company located?

Ohio


The nickel hydrogen battery was used for the first time in 1977 aboard the U.S. Navy's Navigation technology satellite-2 (NTS-2). For example, the ISS, Mars Odyssey and the Mars Global Surveyor are equipped with nickel-hydrogen batteries. In the dark part of its orbit, the Hubble Space Telescope is also powered by nickel-hydrogen batteries, which were finally replaced in May 2009, more than 19 years after launch, and 13 years over their design life.

What year was the first nickel hydrogen battery used?

In what year did the hubble space telescope finally get the nickel hydrogen battery?


Because of its simple atomic structure, consisting only of a proton and an electron, the hydrogen atom, together with the spectrum of light produced from it or absorbed by it, has been central to the development of the theory of atomic structure. Furthermore, the corresponding simplicity of the hydrogen molecule and the corresponding cation H+
2 allowed fuller understanding of the nature of the chemical bond, which followed shortly after the quantum mechanical treatment of the hydrogen atom had been developed in the mid-1920s.

What is the hydrogen atom made up of?

a proton and an electron

What theory is the hydrogen atom a big part of?

atomic structure

When was the quantum mechanical treatment of the hydrogen atom developed?


One of the first quantum effects to be explicitly noticed (but not understood at the time) was a Maxwell observation involving hydrogen, half a century before full quantum mechanical theory arrived. Maxwell observed that the specific heat capacity of H2 unaccountably departs from that of a diatomic gas below room temperature and begins to increasingly resemble that of a monatomic gas at cryogenic temperatures. According to quantum theory, this behavior arises from the spacing of the (quantized) rotational energy levels, which are particularly wide-spaced in H2 because of its low mass. These widely spaced levels inhibit equal partition of heat energy into rotational motion in hydrogen at low temperatures. Diatomic gases composed of heavier atoms do not have such widely spaced levels and do not exhibit the same effect.

Who observed the specific heat capacity of H2?

Maxwell

What cause H2 to resemble monatomic gas?

spacing of the (quantized) rotational energy levels

What theory supports this?

quantum theory


Hydrogen, as atomic H, is the most abundant chemical element in the universe, making up 75% of normal matter by mass and over 90% by number of atoms (most of the mass of the universe, however, is not in the form of chemical-element type matter, but rather is postulated to occur as yet-undetected forms of mass such as dark matter and dark energy). This element is found in great abundance in stars and gas giant planets. Molecular clouds of H2 are associated with star formation. Hydrogen plays a vital role in powering stars through the proton-proton reaction and the CNO cycle nuclear fusion.

What percent of normal matter is hydrogen?

What percent of atoms is hydrogen?

What 2 forms of mass is most of the universe consisted of?

dark matter and dark energy

Clouds of H2 form what?

stars


Throughout the universe, hydrogen is mostly found in the atomic and plasma states whose properties are quite different from molecular hydrogen. As a plasma, hydrogen's electron and proton are not bound together, resulting in very high electrical conductivity and high emissivity (producing the light from the Sun and other stars). The charged particles are highly influenced by magnetic and electric fields. For example, in the solar wind they interact with the Earth's magnetosphere giving rise to Birkeland currents and the aurora. Hydrogen is found in the neutral atomic state in the interstellar medium. The large amount of neutral hydrogen found in the damped Lyman-alpha systems is thought to dominate the cosmological baryonic density of the Universe up to redshift z=4.

In what states is hydrogen mostly found in the universe?

atomic and plasma

Hydrogens electron and proton are not bound together in what state?

plasma

in the interstellar medium, what state is hydrogen in?

neutral atomic state

The neutral hydrogen found in the damped Lyman-alpha systems dominates what?

cosmological baryonic density of the Universe


Under ordinary conditions on Earth, elemental hydrogen exists as the diatomic gas, H2. However, hydrogen gas is very rare in the Earth's atmosphere (1 ppm by volume) because of its light weight, which enables it to escape from Earth's gravity more easily than heavier gases. However, hydrogen is the third most abundant element on the Earth's surface, mostly in the form of chemical compounds such as hydrocarbons and water. Hydrogen gas is produced by some bacteria and algae and is a natural component of flatus, as is methane, itself a hydrogen source of increasing importance.

How abundant is hydrogen on the earths surface?

third most abundant

what produces hydrogen gas?

bacteria and algae


A molecular form called protonated molecular hydrogen (H+
3) is found in the interstellar medium, where it is generated by ionization of molecular hydrogen from cosmic rays. This charged ion has also been observed in the upper atmosphere of the planet Jupiter. The ion is relatively stable in the environment of outer space due to the low temperature and density. H+
3 is one of the most abundant ions in the Universe, and it plays a notable role in the chemistry of the interstellar medium. Neutral triatomic hydrogen H3 can only exist in an excited form and is unstable. By contrast, the positive hydrogen molecular ion (H+
2) is a rare molecule in the universe.

What molecular form is found in the interstellar medium?

protonated molecular hydrogen

What generates protonated molecular hydrogen?

ionization of molecular hydrogen from cosmic rays

On what planet can you find  protonated molecular hydrogen?

Jupiter

In what way can Neutral triatomic hydrogen exist?

excited form


H
2 is produced in chemistry and biology laboratories, often as a by-product of other reactions; in industry for the hydrogenation of unsaturated substrates; and in nature as a means of expelling reducing equivalents in biochemical reactions.

How does nature produce H2?

expelling reducing equivalents in biochemical reactions

How do labs produce H2?

by-product of other reactions


The electrolysis of water is a simple method of producing hydrogen. A low voltage current is run through the water, and gaseous oxygen forms at the anode while gaseous hydrogen forms at the cathode. Typically the cathode is made from platinum or another inert metal when producing hydrogen for storage. If, however, the gas is to be burnt on site, oxygen is desirable to assist the combustion, and so both electrodes would be made from inert metals. (Iron, for instance, would oxidize, and thus decrease the amount of oxygen given off.) The theoretical maximum efficiency (electricity used vs. energetic value of hydrogen produced) is in the range 80–94%.

What is an easy way to produce hydrogen?

electrolysis of water

Where does the gaseous oxygen form at?

anode

Where does the gaseous hydrogen form at?

cathode


An alloy of aluminium and gallium in pellet form added to water can be used to generate hydrogen. The process also produces alumina, but the expensive gallium, which prevents the formation of an oxide skin on the pellets, can be re-used. This has important potential implications for a hydrogen economy, as hydrogen can be produced on-site and does not need to be transported.

When you combine an alloy of alluminum and gallium to water, what do you get?

hydrogen

What else can it produce?

alumina

What can be reused after the formation?

the expensive gallium


Hydrogen can be prepared in several different ways, but economically the most important processes involve removal of hydrogen from hydrocarbons. Commercial bulk hydrogen is usually produced by the steam reforming of natural gas. At high temperatures (1000–1400 K, 700–1100 °C or 1300–2000 °F), steam (water vapor) reacts with methane to yield carbon monoxide and H
2.

The most economical way to prepare hydrogen involves removing it from what?

hydrocarbons

What temperature is needed for steam to react with methane?

1000–1400 K, 700–1100 °C or 1300–2000 °F


This reaction is favored at low pressures but is nonetheless conducted at high pressures (2.0  MPa, 20 atm or 600 inHg). This is because high-pressure H
2 is the most marketable product and Pressure Swing Adsorption (PSA) purification systems work better at higher pressures. The product mixture is known as "synthesis gas" because it is often used directly for the production of methanol and related compounds. Hydrocarbons other than methane can be used to produce synthesis gas with varying product ratios. One of the many complications to this highly optimized technology is the formation of coke or carbon:

At what pressure does PSA work best in?

high pressures

What is synthesis gas used for?

production of methanol

Besides methane, what else can be used to produce synthesis gas?

Hydrocarbons


Consequently, steam reforming typically employs an excess of H
2O. Additional hydrogen can be recovered from the steam by use of carbon monoxide through the water gas shift reaction, especially with an iron oxide catalyst. This reaction is also a common industrial source of carbon dioxide:

How can it be recovered through steam?

use of carbon monoxide through the water gas shift reaction


Hydrogen is sometimes produced and consumed in the same industrial process, without being separated. In the Haber process for the production of ammonia, hydrogen is generated from natural gas. Electrolysis of brine to yield chlorine also produces hydrogen as a co-product.

When hydrogen is generated from natural gas, what des it produce?

ammonia

How is hydrogen produced as a co product?

Electrolysis of brine to yield chlorine


There are more than 200 thermochemical cycles which can be used for water splitting, around a dozen of these cycles such as the iron oxide cycle, cerium(IV) oxide–cerium(III) oxide cycle, zinc zinc-oxide cycle, sulfur-iodine cycle, copper-chlorine cycle and hybrid sulfur cycle are under research and in testing phase to produce hydrogen and oxygen from water and heat without using electricity. A number of laboratories (including in France, Germany, Greece, Japan, and the USA) are developing thermochemical methods to produce hydrogen from solar energy and water.

What are the thermochemical cycyles in a testing phase for?

produce hydrogen and oxygen from water and heat without using electricity

What are labs trying to produce hydrogen from?

solar energy and water

What countries are testing this?

France, Germany, Greece, Japan, and the USA


Under anaerobic conditions, iron and steel alloys are slowly oxidized by the protons of water concomitantly reduced in molecular hydrogen (H
2). The anaerobic corrosion of iron leads first to the formation of ferrous hydroxide (green rust) and can be described by the following reaction:

What condition is iron and steel alloys slowly oxidized?

anaerobic

What does the anaerobic corrosion of iron lead to?

formation of ferrous hydroxide

What is another name for formation of ferrous hydroxide?

green rust


In its turn, under anaerobic conditions, the ferrous hydroxide (Fe(OH)
2 ) can be oxidized by the protons of water to form magnetite and molecular hydrogen. This process is described by the Schikorr reaction:

Under what condition can ferrous hydroxide be oxidized?

anaerobic

What does this process form?

magnetite and molecular hydrogen

What reaction describes this process?

Schikorr reaction


In the absence of atmospheric oxygen (O
2), in deep geological conditions prevailing far away from Earth atmosphere, hydrogen (H
2) is produced during the process of serpentinization by the anaerobic oxidation by the water protons (H+) of the ferrous (Fe2+) silicate present in the crystal lattice of the fayalite (Fe
2SiO
4, the olivine iron-endmember). The corresponding reaction leading to the formation of magnetite (Fe
3O
4), quartz (SiO
2) and hydrogen (H
2) is the following:

How is hydrogen produced when there is no atmospheric oxygen?

serpentinization by the anaerobic oxidation

Where do you find silicate?

crystal lattice of the fayalite


From all the fault gases formed in power transformers, hydrogen is the most common and is generated under most fault conditions; thus, formation of hydrogen is an early indication of serious problems in the transformer's life cycle.

What is the most common gas found in power tranformers?

hydrogen


Large quantities of H
2 are needed in the petroleum and chemical industries. The largest application of H
2 is for the processing ("upgrading") of fossil fuels, and in the production of ammonia. The key consumers of H
2 in the petrochemical plant include hydrodealkylation, hydrodesulfurization, and hydrocracking. H
2 has several other important uses. H
2 is used as a hydrogenating agent, particularly in increasing the level of saturation of unsaturated fats and oils (found in items such as margarine), and in the production of methanol. It is similarly the source of hydrogen in the manufacture of hydrochloric acid. H
2 is also used as a reducing agent of metallic ores.

Where are large quantities of H2 needed?

petroleum and chemical industries

What are the consumers of H2 in petrochemical plant?

hydrodealkylation, hydrodesulfurization, and hydrocracking


Hydrogen is highly soluble in many rare earth and transition metals and is soluble in both nanocrystalline and amorphous metals. Hydrogen solubility in metals is influenced by local distortions or impurities in the crystal lattice. These properties may be useful when hydrogen is purified by passage through hot palladium disks, but the gas's high solubility is a metallurgical problem, contributing to the embrittlement of many metals, complicating the design of pipelines and storage tanks.

Where is hydrogen highly soluble?

rare earth and transition metals

Where can you find soluble hydrogen?

nanocrystalline and amorphous metals

What influences hydrogens solubility in metals?

local distortions or impurities in the crystal lattice

When are these useful?

when hydrogen is purified by passage through hot palladium disks

When is it damaging?

gas's high solubility is a metallurgical problem, contributing to the embrittlement of many metals, complicating the design of pipelines and storage tanks


Apart from its use as a reactant, H
2 has wide applications in physics and engineering. It is used as a shielding gas in welding methods such as atomic hydrogen welding. H2 is used as the rotor coolant in electrical generators at power stations, because it has the highest thermal conductivity of any gas. Liquid H2 is used in cryogenic research, including superconductivity studies. Because H
2 is lighter than air, having a little more than 1⁄14 of the density of air, it was once widely used as a lifting gas in balloons and airships.

Where else is H2 applied?

in physics and engineering

How is H2 used in electrical generators at power stations?

as the rotor coolant

Why is it used as the rotor coolant?

it has the highest thermal conductivity of any gas

What research uses liquid H2?

cryogenic


In more recent applications, hydrogen is used pure or mixed with nitrogen (sometimes called forming gas) as a tracer gas for minute leak detection. Applications can be found in the automotive, chemical, power generation, aerospace, and telecommunications industries. Hydrogen is an authorized food additive (E 949) that allows food package leak testing among other anti-oxidizing properties.

Why would one use hydrogen mixed with nitrogen?

as a tracer gas for minute leak detection

What industries can you find these applications?

automotive, chemical, power generation, aerospace, and telecommunications

How is hydrogen used as a food additive?

allows food package leak testing


Hydrogen's rarer isotopes also each have specific applications. Deuterium (hydrogen-2) is used in nuclear fission applications as a moderator to slow neutrons, and in nuclear fusion reactions. Deuterium compounds have applications in chemistry and biology in studies of reaction isotope effects. Tritium (hydrogen-3), produced in nuclear reactors, is used in the production of hydrogen bombs, as an isotopic label in the biosciences, and as a radiation source in luminous paints.

What isotope is used in nuclear fission?

Deuterium

Where is tritium produced?

nuclear reactors

What is tritium used for?

production of hydrogen bombs, as an isotopic label in the biosciences, and as a radiation source in luminous paints


Hydrogen is commonly used in power stations as a coolant in generators due to a number of favorable properties that are a direct result of its light diatomic molecules. These include low density, low viscosity, and the highest specific heat and thermal conductivity of all gases.

How is hydrogen used at power stations?

as a coolant in generators

Why is it used as a coolant?

favorable properties that are a direct result of its light diatomic molecules

What are these properties?

low density, low viscosity, and the highest specific heat and thermal conductivity of all gases


Hydrogen is not an energy resource, except in the hypothetical context of commercial nuclear fusion power plants using deuterium or tritium, a technology presently far from development. The Sun's energy comes from nuclear fusion of hydrogen, but this process is difficult to achieve controllably on Earth. Elemental hydrogen from solar, biological, or electrical sources require more energy to make it than is obtained by burning it, so in these cases hydrogen functions as an energy carrier, like a battery. Hydrogen may be obtained from fossil sources (such as methane), but these sources are unsustainable.

Is Hydrogen considered an energy resource?

not

Where does the sun get its energy from?

nuclear fusion of hydrogen

How does hydrogen function when it s burned?

energy carrier


The energy density per unit volume of both liquid hydrogen and compressed hydrogen gas at any practicable pressure is significantly less than that of traditional fuel sources, although the energy density per unit fuel mass is higher. Nevertheless, elemental hydrogen has been widely discussed in the context of energy, as a possible future carrier of energy on an economy-wide scale. For example, CO
2 sequestration followed by carbon capture and storage could be conducted at the point of H
2 production from fossil fuels. Hydrogen used in transportation would burn relatively cleanly, with some NOx emissions, but without carbon emissions. However, the infrastructure costs associated with full conversion to a hydrogen economy would be substantial. Fuel cells can convert hydrogen and oxygen directly to electricity more efficiently than internal combustion engines.

What form of hydrogen has been discussed as a ussage for fuel?

elemental


Hydrogen is employed to saturate broken ("dangling") bonds of amorphous silicon and amorphous carbon that helps stabilizing material properties. It is also a potential electron donor in various oxide materials, including ZnO, SnO2, CdO, MgO, ZrO2, HfO2, La2O3, Y2O3, TiO2, SrTiO3, LaAlO3, SiO2, Al2O3, ZrSiO4, HfSiO4, and SrZrO3.

Why is hydrogen employed?

to saturate broken ("dangling") bonds of amorphous silicon and amorphous carbon that helps stabilizing material properties

How is hydrogen used in oxide materials?

a potential electron donor

What oxide materials use hydrogen as an electron donor?

ZnO, SnO2, CdO, MgO, ZrO2, HfO2, La2O3, Y2O3, TiO2, SrTiO3, LaAlO3, SiO2, Al2O3, ZrSiO4, HfSiO4, and SrZrO3


H2 is a product of some types of anaerobic metabolism and is produced by several microorganisms, usually via reactions catalyzed by iron- or nickel-containing enzymes called hydrogenases. These enzymes catalyze the reversible redox reaction between H2 and its component two protons and two electrons. Creation of hydrogen gas occurs in the transfer of reducing equivalents produced during pyruvate fermentation to water. The natural cycle of hydrogen production and consumption by organisms is called the hydrogen cycle.

What enzymes are used to produce H2?

hydrogenases

When does hydrogen gas occur?

in the transfer of reducing equivalents produced during pyruvate fermentation to water

What is the natural cycle of hydrogen production and consumption by organisms called?

hydrogen cycle


Water splitting, in which water is decomposed into its component protons, electrons, and oxygen, occurs in the light reactions in all photosynthetic organisms. Some such organisms, including the alga Chlamydomonas reinhardtii and cyanobacteria, have evolved a second step in the dark reactions in which protons and electrons are reduced to form H2 gas by specialized hydrogenases in the chloroplast. Efforts have been undertaken to genetically modify cyanobacterial hydrogenases to efficiently synthesize H2 gas even in the presence of oxygen. Efforts have also been undertaken with genetically modified alga in a bioreactor.

What is the decomposition of water into its components called?

Water splitting

Where does water splitting occur?

in the light reactions in all photosynthetic organisms

What organisms can form H2 gas?

alga Chlamydomonas reinhardtii and cyanobacteria

How are these gases formed?

by specialized hydrogenases in the chloroplast


Hydrogen poses a number of hazards to human safety, from potential detonations and fires when mixed with air to being an asphyxiant in its pure, oxygen-free form. In addition, liquid hydrogen is a cryogen and presents dangers (such as frostbite) associated with very cold liquids. Hydrogen dissolves in many metals, and, in addition to leaking out, may have adverse effects on them, such as hydrogen embrittlement, leading to cracks and explosions. Hydrogen gas leaking into external air may spontaneously ignite. Moreover, hydrogen fire, while being extremely hot, is almost invisible, and thus can lead to accidental burns.

What threats can hydrogen cause to human saftey?

potential detonations and fires when mixed with air to being an asphyxiant in its pure, oxygen-free form

What can hydrogen embrittlement lead to?

cracks and explosions


Even interpreting the hydrogen data (including safety data) is confounded by a number of phenomena. Many physical and chemical properties of hydrogen depend on the parahydrogen/orthohydrogen ratio (it often takes days or weeks at a given temperature to reach the equilibrium ratio, for which the data is usually given). Hydrogen detonation parameters, such as critical detonation pressure and temperature, strongly depend on the container geometry.

What do physical and chemical properties of hydrogen depend on?

the parahydrogen/orthohydrogen ratio

How long can it take to reach the equilibrium ratio?

days or weeks

What do Hydrogen detonation parameters depend on?

container geometry