Sodium tetratioarsenate

Sodium tetratioarsenate
Sodium tetratioarsenate
Are common
Systematic ; name	Sodium tetratioarsenate
Traditional names	Sodium Thio Arsenic
Chem. formula	Na 3 [AsS 4 ]
Physical properties
condition	light yellow crystals
Molar mass	272.15 g / mol
Optical properties
Refractive index	hydrate - 1,6802

Sodium tetratioarsenate is an inorganic compound, a complex salt of sodium and arsenic alkali metal sulfides with the formula Na ₃ [AsS ₄ ], colorless crystals soluble in water form crystalline hydrates .

Content

Getting

Dissolution of arsenic sulfide in a saturated solution of sodium sulfide :

{\mathsf {As_{2}S_{5}+3Na_{2}S\ {\xrightarrow {50-60^{o}C}}\ 2Na_{3}[AsS_{4}]}}

{\ displaystyle {\ mathsf {As_ {2} S_ {5} + 3Na_ {2} S \ {\ xrightarrow {50-60 ^ {o} C}} \ 2Na_ {3} [AsS_ {4}]}}}

Alkaline decomposition of arsenic sulfide :

{\mathsf {4As_{2}S_{5}+24NaOH\ {\xrightarrow {}}\ 3Na_{3}AsO_{4}+5Na_{3}[AsS_{4}]+12H_{2}O}}

{\ displaystyle {\ mathsf {4As_ {2} S_ {5} + 24NaOH \ {\ xrightarrow {}} \ 3Na_ {3} AsO_ {4} + 5Na_ {3} [AsS_ {4}] + 12H_ {2} O }}}

The dissolution of tetrasulfide tetrasulfide in a suspension of sulfur in a solution of sodium sulfide:

{\mathsf {As_{4}S_{4}+6Na_{2}S+6S\ {\xrightarrow {100^{o}C}}\ 4Na_{3}[AsS_{4}]}}

{\ displaystyle {\ mathsf {As_ {4} S_ {4} + 6Na_ {2} S + 6S \ {\ xrightarrow {100 ^ {o} C}} \ 4Na_ {3} [AsS_ {4}]}}}

Physical Properties

Sodium tetratioarsenate forms colorless or light yellow crystals.

Soluble in cold water, insoluble in ethanol .

It forms crystalline hydrates Na ₃ [AsS ₄ ] • 7.5H ₂ O and Na ₃ [AsS ₄ ] • 8H ₂ O.

Chemical Properties

Anhydrous salt is obtained by drying crystalline hydrate in vacuum :

{\mathsf {4Na_{3}[AsS_{4}]\cdot 8H_{2}O\ {\xrightarrow[{-H_{2}O}]{P_{2}O_{5},80-120^{o}C}}\ 4Na_{3}[AsS_{4}]}}

{\ displaystyle {\ mathsf {4Na_ {3} [AsS_ {4}] \ cdot 8H_ {2} O \ {\ xrightarrow [{- H_ {2} O}] {P_ {2} O_ {5}, 80- 120 ^ {o} C}} \ 4Na_ {3} [AsS_ {4}]}}}

When heated, decomposes:

{\mathsf {2Na_{3}[AsS_{4}]\ {\xrightarrow {450-500^{o}C}}\ 3Na_{2}S+As_{2}S_{3}+2S}}

{\ displaystyle {\ mathsf {2Na_ {3} [AsS_ {4}] \ {\ xrightarrow {450-500 ^ {o} C}} \ 3Na_ {2} S + As_ {2} S_ {3} + 2S} }}

Decomposes in hot water:

{\mathsf {Na_{3}[AsS_{4}]+2H_{2}O\ {\xrightarrow {80^{o}C}}\ Na_{3}[AsS_{2}O_{2}]+2H_{2}S\uparrow }}

{\ displaystyle {\ mathsf {Na_ {3} [AsS_ {4}] + 2H_ {2} O \ {\ xrightarrow {80 ^ {o} C}} \ Na_ {3} [AsS_ {2} O_ {2} ] + 2H_ {2} S \ uparrow}}}

Decomposed by acids:

{\mathsf {2Na_{3}[AsS_{4}]+6HCl\ {\xrightarrow {0^{o}C}}\ 6NaCl+As_{2}S_{5}\downarrow +3H_{2}S\uparrow }}

{\ displaystyle {\ mathsf {2Na_ {3} [AsS_ {4}] + 6HCl \ {\ xrightarrow {0 ^ {o} C}} \ 6NaCl + As_ {2} S_ {5} \ downarrow + 3H_ {2} S \ uparrow}}}

{\mathsf {2Na_{3}[AsS_{4}]+6HCl\ {\xrightarrow {100^{o}C}}\ 6NaCl+As_{2}S_{3}\downarrow +2S\downarrow +3H_{2}S\uparrow }}

{\ displaystyle {\ mathsf {2Na_ {3} [AsS_ {4}] + 6HCl \ {\ xrightarrow {100 ^ {o} C}} \ 6NaCl + As_ {2} S_ {3} \ downarrow + 2S \ downarrow + 3H_ {2} S \ uparrow}}}

Decomposed by alkalis:

{\mathsf {Na_{3}[AsS_{4}]+6NaOH\ {\xrightarrow {}}\ Na_{3}[AsS_{2}O_{2}]+2Na_{2}S+2H_{2}O}}

{\ displaystyle {\ mathsf {Na_ {3} [AsS_ {4}] + 6NaOH \ {\ xrightarrow {}} \ Na_ {3} [AsS_ {2} O_ {2}] + 2Na_ {2} S + 2H_ { 2} O}}}

The solution is slowly oxidized by atmospheric oxygen :

{\mathsf {2Na_{3}[AsS_{4}]+O_{2}\ {\xrightarrow {}}\ Na_{3}[AsS_{2}O_{2}]+2S\downarrow }}

{\ displaystyle {\ mathsf {2Na_ {3} [AsS_ {4}] + O_ {2} \ {\ xrightarrow {}} \ Na_ {3} [AsS_ {2} O_ {2}] + 2S \ downarrow}} }

Oxidized by oxygen during calcination

{\mathsf {Na_{3}[AsS_{4}]+6O_{2}\ {\xrightarrow {500^{o}C}}\ Na_{3}AsO_{4}+4SO_{2}}}

{\ displaystyle {\ mathsf {Na_ {3} [AsS_ {4}] + 6O_ {2} \ {\ xrightarrow {500 ^ {o} C}} \ Na_ {3} AsO_ {4} + 4SO_ {2}} }}

Literature

Chemical Encyclopedia / Editorial Board: Knunyants I.L. et al. - M .: Soviet Encyclopedia, 1992. - T. 3. - 639 p. - ISBN 5-82270-039-8 .
Chemistry Handbook / Editorial: Nikolsky B.P. et al. - 3rd ed., rev. - L .: Chemistry, 1971. - T. 2. - 1168 p.
Lidin R.A. and other Chemical properties of inorganic substances: Textbook. manual for universities. - 3rd ed., Rev. - M .: Chemistry, 2000 .-- 480 p. - ISBN 5-7245-1163-0 .
Inorganic Synthesis Guide: 6 Vol. / Ed. Brower G. - M .: Mir, 1985 .-- T. 2 .-- 338 p.