Strontium carbide

Strontium carbide (also more precisely known as strontium acetylide or strontium dicarbide) is a <a href="/facts/Salt_(chemistry)/lsSKwGpn">salt</a> with chemical formula SrC2. It was first synthesized by <a href="/facts/Moissan/h4lE3nda">Moissan</a> in 1894. It consists of <a href="/facts/Strontium/ABaA5qQK">strontium</a> <a href="/facts/Cations/wrbwhF3z">cations</a> Sr2+ and <a href="/facts/Acetylide/3u0EMxz3">acetylide</a> <a href="/facts/Anions/wrbwhF3z">anions</a> −C≡C−.
Strontium carbide can be formed in an <a href="/facts/Electric_arc_furnace/GgYK6Nz1">electric arc furnace</a> from <a href="/facts/Strontium_carbonate/08rRdbXQ">strontium carbonate</a> and a reductant, such as a <a href="/facts/Reducing_sugar/PmdhuGhR">reducing sugar</a> or <a href="/facts/Magnesium/XyIhd2FG">magnesium</a> metal. Alternatively, <a href="/facts/Carbothermal_reduction/gj0GA25m">carbothermal reduction</a> of <a href="/facts/Strontium_oxide/hxr7KKj5">strontium oxide</a> with graphite begins around 150 °C and is <a href="/facts/Catalysis/LPBS7TQC">catalyzed</a> by <a href="/facts/Calcium_oxide/Wh9C8l7j">calcium oxide</a>. Classical <a href="/facts/Organic_chemistry/djxhxaNg">organic chemistry</a> syntheses include <a href="/facts/Transmetallation/Mm0hQzp3">transmetallation</a> from mercury acetylide or an acid-base reaction between di<a href="/facts/Benzyl/kHmqYwqH">benzyl</a>strontium and <a href="/facts/Acetylene/yaDh6cmJ">acetylene</a>, although these techniques often produce <a href="/facts/Coordination_complex/1tCyeQUm">complexes</a> with the solvent. Direct formation from the elements has a notional <a href="/facts/Enthalpy_of_formation/UFgGC7UQ">enthalpy</a> of −20 kcal/mol.
Nevertheless, strontium carbide may be only <a href="/facts/Metastable/H72SMWof">metastable</a> when <a href="/facts/Endofullerene/4XnqTsxf">encapsulated in a fullerene</a>. It slowly <a href="/facts/Hydrolyze/JTvwIHPs">hydrolyzes</a> in air to <a href="/facts/Acetylene/yaDh6cmJ">acetylene</a>.
The material is <a href="/facts/Polymorphism_(crystals)/bu2tqsB9">polymorphic</a>, forming a <a href="/facts/Monoclinic_crystal_structure/5PCwXvzX">monoclinic crystal structure</a> akin to <a href="/facts/Calcium_carbide/4AxCfuLM">calcium carbide</a> II and a <a href="/facts/Black/Sl9vnhcG">black</a> <a href="/facts/Tetragonal_crystal_structure/12Aop255">tetragonal</a> phase. Heated to 370 °C, it reversibly converts to a <a href="/facts/Face-centered_cubic/92Co7BKM">face-centered cubic</a> (fcc) lattice. Yttrium carbide retains the fcc lattice down to <a href="/facts/Room_temperature/YHwUIUTE">room temperature</a>; the difference is a 3eg orbital that strontium lacks the electrons to fill. <a href="/facts/Cyanamide/BNJKoGc0">Cyanamide</a> impurities stabilize one other strontium carbide polymorph, just as they do for calcium carbide. The stabilized calcium carbide polymorph is <a href="/facts/Triclinic/Y6yEdqfN">triclinic</a>, and the strontium carbide polymorph is believed to be so as well.
At roughly 1800 °C, strontium carbide <a href="/facts/Melting/zhhDBo5V">melts</a>. It forms a <a href="/facts/Solid_solution/Mla7z8dc">solid solution</a> with europium carbide, as Eu+2 has an almost identical <a href="/facts/Ionic_radius/C3dwKrrB">ionic radius</a> to Sr+2.
Strontium carbide is a <a href="/facts/Chemical_intermediate/BjD9HAHt">chemical intermediate</a> in an archaic <a href="/facts/Carbon-14_dating/qjNglhKP">carbon-14 dating</a> technique: burning the material to be dated releases <a href="/facts/Carbon_dioxide/xGzpppEp">carbon dioxide</a>, <a href="/facts/Chemical_trap/NUoApMRS">trapped</a> as <a href="/facts/Strontium_carbonate/08rRdbXQ">strontium carbonate</a>. Magnesium then reduces the carbonate to strontium carbide and hydrolysis releases acetylene. The radioactive decay of the acetylene can then be observed directly or heating to 600 °C polymerizes the acetylene to <a href="/facts/Benzene/Fguue7nr">benzene</a> for a liquid scintillator.
<a href="/facts/Solid_state_metathesis/Uy7ogTjs">Solid state metathesis</a> of strontium carbide and a (complex) metal <a href="/facts/Oxide/DXtoVe1C">oxide</a> gives the corresponding metal <a href="/facts/Carbide/xfCMTjYJ">carbide</a> and strontium oxide. The latter washes away easily in pure water.

Strontium carbide open-in-new

Strontium carbide