Ammonium Paramolybdate

Ammonium Paramolybdate
Ammonium Paramolybdate
Are common
Systematic ; name	24-oxoheptamolybdate (VI) ammonium
Traditional names	ammonium heptamolybdate; ammonium paramolybdate; ammonium paramolybdate
Chem. formula	(NH 4 ) 6 Mo 7 O 24
Physical properties
condition	colorless (white) crystals
Molar mass	1163.79 g / mol
Density	hydr. 2,498 g / cm³
Chemical properties
Water solubility	280 20 ; 470 80-90 g / 100 ml
Classification
Reg. CAS number	12027-67-7
Pubchem
Reg. EINECS number
SMILES
Inchi
Reg. EC number	234-320-9
Chemspider

Ammonium paramolybdate - inorganic compound, ammonium salt and non-isolated paramolybdic acid with the formula (NH ₄ ) ₆ Mo ₇ O ₂₄ , colorless (white) crystals, soluble in water, forms crystalline hydrates .

Content

Getting

The dissolution of molybdenum oxide (VI) in a diluted cold ammonia solution:

{\mathsf {7MoO_{3}+6(NH_{3}\cdot H_{2}O)\ {\xrightarrow {0^{o}C}}\ (NH_{4})_{6}Mo_{7}O_{24}+3H_{2}O}}

{\ displaystyle {\ mathsf {7MoO_ {3} +6 (NH_ {3} \ cdot H_ {2} O) \ {\ xrightarrow {0 ^ {o} C}} \ (NH_ {4}) _ {6} Mo_ {7} O_ {24} + 3H_ {2} O}}}

Physical Properties

Ammonium paramolybdate forms colorless (white) crystals.

Forms crystalline hydrates of the composition (NH ₄ ) ₆ Mo ₇ O ₂₄ • n H ₂ O, where n = 4, 24.

The most studied crystalline hydrate is (NH ₄ ) ₆ Mo ₇ O ₂₄ • 4H ₂ O, which forms colorless (white) crystals of the monoclinic syngony , space group P 2 ₁ / n , cell parameters a = 1.0141 nm, b = 3.6125 nm , c = 0.8383 nm, β = 111.98 °, Z = 4.

Chemical Properties

Decomposes when heated in several stages:

{\mathsf {(NH_{4})_{6}Mo_{7}O_{24}\cdot 4H_{2}O\ {\xrightarrow[{-H_{2}O}]{110^{o}C}}\ (NH_{4})_{6}Mo_{7}O_{24}\ {\xrightarrow[{-NH_{3},-H_{2}O}]{200^{o}C}}}}

{\ displaystyle {\ mathsf {(NH_ {4}) _ {6} Mo_ {7} O_ {24} \ cdot 4H_ {2} O \ {\ xrightarrow [{- H_ {2} O}] {110 ^ { o} C}} \ (NH_ {4}) _ {6} Mo_ {7} O_ {24} \ {\ xrightarrow [{- NH_ {3}, - H_ {2} O}] {200 ^ {o} C}}}}}

{\mathsf {{\xrightarrow[{-NH_{3},-H_{2}O}]{200^{o}C}}(NH_{4})_{2}Mo_{4}O_{13}\ {\xrightarrow[{-NH_{3},-H_{2}O}]{280-500^{o}C}}\ MoO_{3}}}

{\ displaystyle {\ mathsf {{\ xrightarrow [{- NH_ {3}, - H_ {2} O}] {200 ^ {o} C}} (NH_ {4}) _ {2} Mo_ {4} O_ {13} \ {\ xrightarrow [{- NH_ {3}, - H_ {2} O}] {280-500 ^ {o} C}} \ MoO_ {3}}}

Reacts with hot concentrated nitric acid :

{\mathsf {(NH_{4})_{6}Mo_{7}O_{24}+6\;HNO_{3}\ {\xrightarrow {100^{o}C}}\ 7\;MoO_{3}\downarrow +\;6\;NH_{4}NO_{3}+3\;H_{2}O}}

{\ displaystyle {\ mathsf {(NH_ {4}) _ {6} Mo_ {7} O_ {24} +6 \; HNO_ {3} \ {\ xrightarrow {100 ^ {o} C}} \ 7 \; MoO_ {3} \ downarrow + \; 6 \; NH_ {4} NO_ {3} +3 \; H_ {2} O}}}

Reacts with concentrated alkalis :

{\mathsf {(NH_{4})_{6}Mo_{7}O_{24}+14\;NaOH\ {\xrightarrow {}}\ 7\;Na_{2}MoO_{4}+6\;NH_{3}+10\;H_{2}O}}

{\ displaystyle {\ mathsf {(NH_ {4}) _ {6} Mo_ {7} O_ {24} +14 \; NaOH \ {\ xrightarrow {}} \ 7 \; Na_ {2} MoO_ {4} + 6 \; NH_ {3} +10 \; H_ {2} O}}}

Reacts with hydrogen:

{\mathsf {(NH_{4})_{6}Mo_{7}O_{24}+7\;H_{2}+3\;H_{2}O\ {\xrightarrow {50^{o}C,Pt}}\ 7\;MoO(OH)_{2}\downarrow +6\;(NH_{3}\cdot H_{2}O)}}

{\ displaystyle {\ mathsf {(NH_ {4}) _ {6} Mo_ {7} O_ {24} +7 \; H_ {2} +3 \; H_ {2} O \ {\ xrightarrow {50 ^ { o} C, Pt}} \ 7 \; MoO (OH) _ {2} \ downarrow +6 \; (NH_ {3} \ cdot H_ {2} O)}}}

Used for qualitative and quantitative determination of phosphoric acid :

{\mathsf {12\;(NH_{4})_{6}Mo_{7}O_{24}+7\;(NH_{4})H_{2}PO_{4}+58\;HNO_{3}\ {\xrightarrow {}}\ 7\;(NH_{4})_{3}[PMo_{12}O_{40}]\downarrow +58\;NH_{4}NO_{3}+36\;H_{2}O}}

{\ displaystyle {\ mathsf {12 \; (NH_ {4}) _ {6} Mo_ {7} O_ {24} +7 \; (NH_ {4}) H_ {2} PO_ {4} +58 \; HNO_ {3} \ {\ xrightarrow {}} \ 7 \; (NH_ {4}) _ {3} [PMo_ {12} O_ {40}] \ downarrow +58 \; NH_ {4} NO_ {3} + 36 \; H_ {2} O}}}

Literature

Chemical Encyclopedia / Redkol .: Knunyants I.L. et al. - M .: Soviet Encyclopedia, 1992. - Vol. 3. - 639 p. - ISBN 5-82270-039-8 .
Chemist Handbook / Redkol .: Nikolsky B.P. et al. - 2nd ed., Rev. - M.-L.: Chemistry, 1966. - T. 1. - 1072 p.
Chemist Handbook / Redkol .: 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: Proc. manual for universities. - 3rd ed., Corr. - M .: Chemistry, 2000. - 480 p. - ISBN 5-7245-1163-0 .
Ripan R., Chetyanu I. Inorganic chemistry. Metal Chemistry. - M .: Mir, 1972. - T. 2. - 871 p.