El­e­ments Mat­ter - Helium

- Veena Pat­ward­han - Spe­cial Correspondent

Chemical Industry Digest - - What’s In? - Veena Pat­ward­han, Spe­cial Correspondent

The sec­ond in this new se­ries cov­ers the lit­tle known as­pects and sto­ries on helium.

What do party bal­loons, space shuttles, MRI ma­chines, and the Large Hadron Col­lider have in com­mon? They all need helium. Whether in the gaseous or liq­uid form, at room tem­per­a­ture or at tem­per­a­tures close to ab­so­lute zero, the world con­sumes around 8 bil­lion cu­bic feet of helium each year for var­i­ous pur­poses.

Af­ter hy­dro­gen, helium is the sec­ond most abun­dant el­e­ment in the uni­verse, and hav­ing an atom with two pro­tons, two neu­trons, and two elec­trons, is also the sec­ond sim­plest of the chem­i­cal el­e­ments. It is the light­est of the no­ble gases and com­pletely in­ert.

Helium has some fas­ci­nat­ing phys­i­cal prop­er­ties. Of all the el­e­ments, it’s boil­ing point −452.1°F (−268.9°C) and melt­ing point −458°F (−272.2°C) are the low­est. As is ev­i­dent from these fig­ures, helium re­mains a gas even at very low tem­per­a­tures, and is in the liq­uid state over a very short tem­per­a­ture range. Just above its melt­ing point, at a tem­per­a­ture of about -27271°C (-456°F), it be­comes a su­per­fluid, that is, it flows up­wards out of a con­tainer de­fy­ing the force of grav­ity. Helium is also the only el­e­ment that can­not be so­lid­i­fied just bby low­er­ing the tem­per­a­ture a at or­di­nary pres­sures. To so­lid­ify it, the pres­sure too has to be in­creased. These pe­cu­liar prop­er­ties of helium make it an im­por­tant el­e­ment in low-tem­per­a­ture re­search.

His­tory of the ‘Sun’ el­e­ment

The most fas­ci­nat­ing fact about the his­tory of this no­blest oof gases is that it was dis­cov­ered twice. First around 92,900,000 miles away from our planet – in the Sun, and only around three decades later on

the Earth.

On a visit to Gun­tur, In­dia, to ob­serve the so­lar eclipse on 18th Au­gust,1868, the

French as­tronomer Pierre Jules César Janssen stud­ied the spec­tral lines of the so­lar promi­nences and re­alised they were bright enough to be stud­ied even in nor­mal day­light. So, the next day, he stud­ied the chro­mo­sphere of the sun again through his spec­tro­scope and dis­cov­ered a yel­low spec­tral line close to those of sodium, but dis­tinct from them. He con­cluded it must be from some un­known el­e­ment in the Sun. Around two months later, on 20th Oc­to­ber, a Bri­tish as­tronomer Sir Joseph Nor­man Lock­yer dis­cov­ered the same spec­tral line ob­serv­ing the Sun’s spec­trum through a more pow­er­ful spec­tro­scope and even mea­sured its wave­length (587.49 nanome­tres). Re­al­is­ing it did not match that of any other known el­e­ment on earth, he and an English chemist Ed­ward Fran­k­land named the el­e­ment helium af­ter the Greek word for the Sun and the Sun God - Hēlios. And so, both Janssen and Lock­yer are cred­ited with first dis­cov­er­ing ex­trater­res­trial helium.

For quite some time af­ter­wards, it was be­lieved helium only ex­isted in the Sun. Till in 1895, the Scot­tish chemist Sir Wil­liam Ram­say dis­cov­ered trace amounts of helium gas in cleveite, a min­eral con­tain­ing ura­nium, while try­ing to pro­duce ar­gon from it. Lock­yer con­firmed it was in­deed helium. Around the same time, Swedish chemist Per Teodor Cleve and his stu­dent Nils Abra­ham Lan­glet also in­de­pen­dently dis­cov­ered helium in the same min­eral. Thus, cleveite be­came the first known earthly source of helium. Ac­tu­ally, Lock­yer had called the new el­e­ment helium as­sum­ing it to be a metal. Later, Ram­say had sug­gested he re-name it as ‘he­lion’ to go with the names of the other no­ble gases. But Lock­yer re­fused and so the name stayed un­changed.

Then, on De­cem­ber 7, 1905, af­ter two years of re­search in their lab­o­ra­tory in Kansas Univer­sity’s Bai­ley Hall, chem­istry pro­fes­sors Hamil­ton P. Cady and David F. McFar­land made a sig­nif­i­cant dis­cov­ery.

They found that the sam­ples of the strange non-flammable gas col­lected from a nat­u­ral gas field in Dex­ter, Kansas, that they had been work­ing on, con­tained con­sid­er­able amounts of helium. Their work re- vealed that nat­u­ral gas was a much bet­ter source for ex­tract­ing helium as com­pared to cleveite. Bai­ley Hall, the site of this sig­nif­i­cant break­through, bears a plaque from the Amer­i­can Chem­i­cal So­ci­ety hon­our­ing the build­ing as a Na­tional Chem­i­cal His­tor­i­cal Land­mark. This dis­cov­ery also led to the de­tec­tion of a mas­sive re­serve of helium be­low the Amer­i­can Great Plains and to the United States be­com­ing the sole sup­plier of helium to the rest of the world.

From help­ing launch rock­ets to sav­ing lives

Helium’s in­ter­est­ing prop­er­ties have been fully ex­ploited for mul­ti­ple ap­pli­ca­tions. The ear­li­est use of helium in large quan­ti­ties was for buoy­ing bal­loons and air­ships. Non-flammable helium-filled air­ships helped win World War II by de­tect­ing the pres­ence of Ger­man sub­marines in the At­lantic and guid­ing US sup­ply and troop ships safely through dan­ger­ous waters. Helium was used to sup­port the pro­duc­tion of atomic en­ergy and played a sig­nif­i­cant role in the mak­ing of the atomic bomb at Los Alamos, New Mexico.

A ma­jor use of helium to­day is for Mag­netic Res­o­nance Imag­ing (MRI) ma­chines. These ma­chines, used for di­ag­nos­ing var­i­ous med­i­cal con­di­tions such as can­cers, tu­mours, brain ill­nesses and heart dam­age, need liq­uid helium for cool­ing the su­per­con­duct­ing mag­net that pro­vides their mag­netic field. Helium also helps cre­ate an in­ert at­mos­phere for weld­ing pro­cesses, fa­cil­i­tat­ing the fabrication of mag­ne­sium and other met­als. Space shuttles need liq­uid helium to clean out

their liq­uid hy­dro­gen and oxy­gen fuel tanks, and also to pres­surise the in­te­rior of liq­uid fuel rock­ets, be­sides con­dens­ing hy­dro­gen and oxy­gen to make rocket fuel and forc­ing the fuel into the en­gines dur­ing rocket launches. Be­ing in the liq­uid state even at -270°C, helium is cold enough to be used in su­per­con­duct­ing de­vices such as sen­si­tive op­ti­cal de­vices and de­tec­tors of mag­netic fields.

Be­sides, helium is also used in leak-de­tec­tion sys­tems, for pre­par­ing the helium-neon gas lasers used in su­per­mar­ket check-outs for scan­ning bar codes, for pre­par­ing helium-oxy­gen mix­tures that deep-sea divers can breathe com­fort­ably, and for cre­at­ing an in­ert at­mos­phere for man­u­fac­tur­ing fi­bre op­tic ca­bles used for in­ter­net sup­ply and ca­ble TV and grow­ing ul­tra­pure crys­tals for sil­i­con wafers. Now, re­search is un­der­way for us­ing it as a coolant in next- gen­er­a­tion nu­clear power plants. An in­cred­i­ble num­ber of ap­pli­ca­tions for an in­ert gas, one would think.

No longer the dis­ap­pear­ing el­e­ment?

For some time now, sci­en­tists have been pre­dict­ing the world could soon run out of helium, a non-re­new­able re­source. Cur­rently, we have no way of man­u­fac­tur­ing it. And once used for as a coolant or for other pur­poses, we can­not re­cy­cle it. Be­ing lighter than air, it im­me­di­ately rises into the at­mos­phere and es­capes into space. All the helium we have is trapped in the earth’s crust.

And while it’s not pos­si­ble to es­ti­mate the ex­act amount of helium deep within the earth’s crust, we do know it is formed when ra­dioac­tive el­e­ments like ura­nium and tho­rium present in rocks deep be­neath the earth’s sur­face de­cay, and then it ac­cu­mu­lates in pock­ets in the crust or in reser­voirs of nat­u­ral gas. When wells are dug for col­lect­ing the nat­u­ral gas, helium gas, that also comes to the sur­face, gets re­leased and es­capes into space.

Re­cently, ge­ol­o­gists from the Uni­ver­si­ties of Ox­ford and Durham found that vol­canic ac­tiv­ity re­leases helium from deep down in the Earth into shal­lower pock­ets closer to its sur­face. Ac­cord­ingly, they be­gan look­ing for such helium pock­ets and found a huge reser­voir of the gas in the Tan­za­nian East African Rift Val­ley in June last year. Ini­tially es­ti­mated to be 54 bil­lion cu­bic feet (ap­prox­i­mately eight times the an­nual global de­mand), re­cent anal­y­sis of the helium de­posit has re­vealed it could be much big­ger - around 98.6 bil­lion cu­bic feet.

Many re­searchers and ge­ol­o­gists have re­ferred to the new find as ‘life-sav­ing’ and as a ‘game-changer’, and are of the view that many more mas­sive helium reser­voirs could be un­earthed in other parts of the world. Af­ter the ear­lier scares, that’s good news in­deed. Good enough to lift our spir­its!

Ref­er­ences

1. John Em­s­ley: Na­ture’s Build­ing Blocks: An A-Z Guide to the el­e­ments - Ox­ford Univer­sity Press, Au­gust 2011

2. Bi­man B. Nath: The Story of Helium and the Birth of Astro­physics - Springer Sci­ence & Busi­ness Me­dia, 10 Nov 2012

3. John H. McCool: High on Helium - Univer­sity of Kansas, www.kuhis­tory.com

4. Fran­cie Diep: 8 Sur­pris­ing High-Tech Uses for Helium - In­no­va­tion News Daily, www.nbc­news.com , 18 May 2012

5. He­len Briggs: Helium dis­cov­ery a ‘game-changer’ - www. bbc.com , 28 June 2016

6. Matthew Gun­ther: Sci­en­tists un­earth one of the world’s largest helium de­posits - Chem­istry World, 30 June 2016

7. Michelle Starr: Mas­sive ‘life-sav­ing’ helium field just turned out to be far big­ger than we’d hoped – www.sci­enceal­ert.com , 10 Oc­to­ber 2017

8. Ber­ganza CJ, Zhang JH: The role of helium gas in medicine - Med­i­cal Gas Re­search, PMC Web, US Na­tional Li­brary of Sci­ence, 4 Au­gust 2013

9. Ho­bart King: Helium: A byprod­uct of the nat­u­ral gas in­dus­try – www.ge­ol­ogy.com.

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