Ammonium chromate

Ammonium chromate
Ammonium chromate
Are common
Systematic ; name	Ammonium chromate
Traditional names	Ammonium Chromate
Chem. formula	(NH 4 ) 2 CrO 4
Physical properties
condition	yellow crystals
Molar mass	152.07 g / mol
Density	1.89; 1.91 g / cm³
Thermal properties
T. melt.	decomp. 180 ° C
Chemical properties
Solubility in water	24.7 0 ; 70.1 75 g / 100 ml
Classification
Reg. CAS number	7788-98-9
PubChem
Reg. EINECS number
Smiles
Inchi
RTECS
ChemSpider

Ammonium (II) chromate is an inorganic compound, a salt of ammonium and chromic acid with the formula (NH ₄ ) ₂ CrO ₄ , yellow crystals, soluble in water.

Content

Getting

Dissolution of chromium oxide (VI) in ammonia solution:

{\mathsf {CrO_{3}+2NH_{3}\cdot H_{2}O\ {\xrightarrow {}}\ (NH_{4})_{2}CrO_{4}+H_{2}O}}

{\ displaystyle {\ mathsf {CrO_ {3} + 2NH_ {3} \ cdot H_ {2} O \ {\ xrightarrow {}} \ (NH_ {4}) _ {2} CrO_ {4} + H_ {2} O}}}

Physical Properties

Ammonium (II) chromate forms yellow crystals of monoclinic syngony , space group P m , cell parameters a = 0.744 nm, b = 0.627 nm, c = 0.615 nm, β = 113.17 °, Z = 2.

It is well soluble in water, poorly soluble in ethanol and acetone .

Chemical Properties

Decomposes on heating

{\mathsf {2(NH_{4})_{2}CrO_{4}\ {\xrightarrow {180^{o}C}}\ Cr_{2}O_{3}+2NH_{3}+N_{2}+5H_{2}O}}

{\ displaystyle {\ mathsf {2 (NH_ {4}) _ {2} CrO_ {4} \ {\ xrightarrow {180 ^ {o} C}} \ Cr_ {2} O_ {3} + 2NH_ {3} + N_ {2} + 5H_ {2} O}}}

During prolonged storage in air, it gradually loses ammonia and turns into ammonium dichromate :

{\mathsf {2(NH_{4})_{2}CrO_{4}\ {\xrightarrow {}}\ (NH_{4})_{2}Cr_{2}O_{7}+2NH_{3}+H_{2}O}}

{\ displaystyle {\ mathsf {2 (NH_ {4}) _ {2} CrO_ {4} \ {\ xrightarrow {}} \ (NH_ {4}) _ {2} Cr_ {2} O_ {7} + 2NH_ {3} + H_ {2} O}}}

Reacts with diluted acids:

{\mathsf {2(NH_{4})_{2}CrO_{4}+2H_{2}SO_{4}\ {\xrightarrow {}}\ (NH_{4})_{2}Cr_{2}O_{7}+2NH_{4}HSO_{4}+H_{2}O}}

{\ displaystyle {\ mathsf {2 (NH_ {4}) _ {2} CrO_ {4} + 2H_ {2} SO_ {4} \ {\ xrightarrow {}} \ (NH_ {4}) _ {2} Cr_ {2} O_ {7} + 2NH_ {4} HSO_ {4} + H_ {2} O}}}

Application

Pickling for dyeing fabrics.
Tanning agent.
A component of the photosensitive layer of photographic materials.

Literature

Chemical Encyclopedia / Editorial: Zefirov N.S. et al. - M .: Big Russian Encyclopedia, 1998. - V. 5. - 783 p. - ISBN 5-85270-310-9 .
Chemistry Handbook / Editorial: Nikolsky B.P. et al. - 2nd ed., rev. - M.-L.: Chemistry, 1966. - T. 1. - 1072 p.
Chemistry Handbook / Editorial: Nikolsky B.P. et al. - 3rd ed., rev. - L .: Chemistry, 1971. - T. 2. - 1168 p.
Ripan R., Chetyanu I. Inorganic chemistry. Chemistry of metals. - M .: Mir, 1972. - T. 2. - 871 p.

Ammonium chromate
Are common
Systematic name	Ammonium chromate
Traditional names	Ammonium Chromate
Chem. formula	(NH ₄ ) ₂ CrO ₄
Physical properties
condition	yellow crystals
Molar mass	152.07 g / mol
Density	1.89; 1.91 g / cm³
Thermal properties
T. melt.	decomp. 180 ° C
Chemical properties
Solubility in water	24.7 ⁰ ; 70.1 ⁷⁵ g / 100 ml
Classification
Reg. CAS number	7788-98-9
PubChem
Reg. EINECS number
Smiles
Inchi
RTECS
ChemSpider