Calcium sulphide

Calcium sulphide
Calcium sulphide
General
Systematic ; name	calcium sulfide
Traditional names	calcium sulfide, calcium sulfide
Chem. formula	CaS
Physical properties
condition	white hygroscopic powder
Molar mass	72.143 g / mol
Density	2.59 g / cm³
Thermal properties
T. melt.	2525 ° C
Like heat resistant.	47.51 J / (mol · K)
Enthalpy of Education	−476.98 kJ / mol
Chemical properties
Solubility in water	sparingly soluble
Solubility in other substances	insoluble in alcohol , reacts with acids
Optical properties
Refractive index	2.137
Structure
Coordination geometry	octahedral (Ca 2+ ); octahedral (S 2− )
Crystal structure	cubic ( halite )
Classification
Reg. CAS number	20548-54-3
PubChem
Reg. EINECS number
Smiles
Inchi
Reg. EC number	243-873-5
Chebi
ChemSpider
Security
Toxicity	one 2 one

Calcium sulfide is an inorganic binary chemical compound with the formula Ca S.

Content

1 Receiving
2 Physical properties
3 Chemical properties
4 Application

Getting

The well-known mineral is oldhamite ( English Oldhamite ) consisting of calcium sulfide with impurities of magnesium , sodium , iron , copper . The crystals are pale brown, turning into dark brown.

Direct synthesis of elements:

{\mathsf {Ca+S~{\xrightarrow {150~^{\circ }C}}\ CaS}}

{\ displaystyle {\ mathsf {Ca + S ~ {\ xrightarrow {150 ~ ^ {\ circ} C}} \ CaS}}}

The reaction of calcium hydride in hydrogen sulfide :

{\mathsf {CaH_{2}+H_{2}S~{\xrightarrow {500{-}600~^{\circ }C}}\ CaS+2H_{2}}}

{\ displaystyle {\ mathsf {CaH_ {2} + H_ {2} S ~ {\ xrightarrow {500 {-} 600 ~ ^ {\ circ} C}} \ CaS + 2H_ {2}}}}

From calcium carbonate :

{\mathsf {CaCO_{3}+H_{2}S~{\xrightarrow {900~^{\circ }C}}\ CaS+H_{2}O+CO_{2}}}

{\ displaystyle {\ mathsf {CaCO_ {3} + H_ {2} S ~ {\ xrightarrow {900 ~ ^ {\ circ} C}} \ CaS + H_ {2} O + CO_ {2}}}}

Reduction of calcium sulfate :

{\mathsf {CaSO_{4}+3C~{\xrightarrow {900~^{\circ }C}}\ CaS+2CO+CO_{2}}}

{\ displaystyle {\ mathsf {CaSO_ {4} + 3C ~ {\ xrightarrow {900 ~ ^ {\ circ} C}} \ CaS + 2CO + CO_ {2}}}}

{\mathsf {CaSO_{4}+4CO~{\xrightarrow {600{-}800~^{\circ }C}}\ CaS+4CO_{2}}}

{\ displaystyle {\ mathsf {CaSO_ {4} + 4CO ~ {\ xrightarrow {600 {-} 800 ~ ^ {\ circ} C}} \ CaS + 4CO_ {2}}}}

Physical Properties

White crystals, cubic face-centered lattice of NaCl type (a = 0.6008 nm). It decomposes upon melting. In the crystal, each S ^2– ion is surrounded by an octahedron consisting of six Ca ^{2+ ions} , while each Ca ^{2+ ion is} surrounded by six S ^2– ions.

Slightly soluble in cold water, does not form crystalline hydrates. Like many other sulfides, calcium sulfide in the presence of water undergoes hydrolysis and has the smell of hydrogen sulfide .

Chemical Properties

When heated, decomposes into components:

{\mathsf {CaS\ {\xrightarrow {>2450^{o}C}}\ Ca+S}}

{\ displaystyle {\ mathsf {CaS \ {\ xrightarrow {> 2450 ^ {o} C}} \ Ca + S}}}

In boiling water it is completely hydrolyzed:

{\mathsf {CaS+2H_{2}O\ {\xrightarrow {100^{o}C}}\ Ca(OH)_{2}+H_{2}S}}

{\ displaystyle {\ mathsf {CaS + 2H_ {2} O \ {\ xrightarrow {100 ^ {o} C}} \ Ca (OH) _ {2} + H_ {2} S}}}

Diluted acids displace hydrogen sulfide from salt:

{\mathsf {CaS+2HCl\ \rightarrow \ CaCl_{2}+H_{2}S}}

{\ displaystyle {\ mathsf {CaS + 2HCl \ \ rightarrow \ CaCl_ {2} + H_ {2} S}}}

Concentrated oxidizing acids oxidize hydrogen sulfide:

{\mathsf {CaS+4HNO_{3}\ \rightarrow \ Ca(NO_{3})_{2}+S+2NO_{2}+2H_{2}O}}

{\ displaystyle {\ mathsf {CaS + 4HNO_ {3} \ \ rightarrow \ Ca (NO_ {3}) _ {2} + S + 2NO_ {2} + 2H_ {2} O}}}

Hydrogen sulfide is a weak acid and can be displaced from salts even by carbon dioxide:

{\mathsf {CaS+CO_{2}+H_{2}O\ \rightarrow \ CaCO_{3}+H_{2}S}}

{\ displaystyle {\ mathsf {CaS + CO_ {2} + H_ {2} O \ \ rightarrow \ CaCO_ {3} + H_ {2} S}}}

With an excess of hydrogen sulfide, hydrosulfides are formed:

{\mathsf {CaS+H_{2}S\ \rightarrow \ Ca(HS)_{2}}}

{\ displaystyle {\ mathsf {CaS + H_ {2} S \ \ rightarrow \ Ca (HS) _ {2}}}}

Like all sulfides, calcium sulfide is oxidized by oxygen:

{\mathsf {CaS+2O_{2}\ {\xrightarrow {700-800^{o}C}}\ CaSO_{4}}}

{\ displaystyle {\ mathsf {CaS + 2O_ {2} \ {\ xrightarrow {700-800 ^ {o} C}} \ CaSO_ {4}}}}

Application

Used for the preparation of phosphors , as well as in the leather industry for removing hair from skins, it is also used in the medical industry as a homeopathic remedy .