Hafnium Dihydroxide Oxide

Hafnium Dihydroxide Oxide
Hafnium Dihydroxide Oxide
Are common
Systematic ; name	Hafnium Dihydroxide Oxide
Traditional names	metagaphnic acid
Chem. formula	HfO (OH) 2
Physical properties
condition	white amorphous substance
Molar mass	228.50 g / mol

Hafnium dihydroxide oxide (metahafnium acid) is an inorganic compound, hafnium oxohydroxide with the formula HfO (OH) ₂ , a white amorphous substance, insoluble in water.

Content

Getting

Heating the hydrated form of hafnium (IV) oxide :

{\mathsf {HfO_{2}\cdot nH_{2}O\ {\xrightarrow {140-200^{o}C}}\ HfO(OH)_{2}+(n-1)H_{2}O}}

{\ displaystyle {\ mathsf {HfO_ {2} \ cdot nH_ {2} O \ {\ xrightarrow {140-200 ^ {o} C}} \ HfO (OH) _ {2} + (n-1) H_ { 2} O}}}

The action of an alkali solution on the soluble hafnium oxosol:

{\mathsf {HfOCl_{2}+2NaOH\ {\xrightarrow {}}\ HfO(OH)_{2}\downarrow +2NaCl_{2}}}

{\ displaystyle {\ mathsf {HfOCl_ {2} + 2NaOH \ {\ xrightarrow {}} \ HfO (OH) _ {2} \ downarrow + 2NaCl_ {2}}}}

The effect of an alkali solution on the soluble hafnium (IV) salt:

{\mathsf {HfCl_{4}+4NaOH\ {\xrightarrow {}}\ HfO(OH)_{2}\downarrow +4NaCl+H_{2}O}}

{\ displaystyle {\ mathsf {HfCl_ {4} + 4NaOH \ {\ xrightarrow {}} \ HfO (OH) _ {2} \ downarrow + 4NaCl + H_ {2} O}}}

Physical Properties

Hafnium dihydroxide oxide is a white amorphous substance.

HfO ₂ • n H ₂ O hydrate precipitates from the solution. Freshly precipitated substance is more chemically active than the “old” precipitate.

Slightly soluble in water, p PR = 28.90.

Chemical Properties

Decomposes on heating:

{\mathsf {HfO(OH)_{2}\ {\xrightarrow {600-1000^{o}C}}\ HfO_{2}+H_{2}O}}

{\ displaystyle {\ mathsf {HfO (OH) _ {2} \ {\ xrightarrow {600-1000 ^ {o} C}} \ HfO_ {2} + H_ {2} O}}}

Reacts with diluted acids :

{\mathsf {HfO(OH)_{2}+2HCl\ {\xrightarrow {}}\ HfOCl_{2}+2H_{2}O}}

{\ displaystyle {\ mathsf {HfO (OH) _ {2} + 2HCl \ {\ xrightarrow {}} \ HfOCl_ {2} + 2H_ {2} O}}}

Reacts with concentrated acids:

{\mathsf {HfO(OH)_{2}+2H_{2}SO_{4}\ {\xrightarrow {}}\ Hf(SO_{4})_{2}\downarrow +3H_{2}O}}

{\ displaystyle {\ mathsf {HfO (OH) _ {2} + 2H_ {2} SO_ {4} \ {\ xrightarrow {}} \ Hf (SO_ {4}) _ {2} \ downarrow + 3H_ {2} O}}}

Reacts with alkalis:

{\mathsf {HfO(OH)_{2}+NaOH+4H_{2}O\ \rightleftarrows \ Na[Hf(H_{2}O)_{3}(OH)_{5}]}}

{\ displaystyle {\ mathsf {HfO (OH) _ {2} + NaOH + 4H_ {2} O \ \ rightleftarrows \ Na [Hf (H_ {2} O) _ {3} (OH) _ {5}]} }}

{\mathsf {HfO(OH)_{2}+2NaOH+H_{2}O\ \rightleftarrows \ Na_{2}[Hf(OH)_{6}]}}

{\ displaystyle {\ mathsf {HfO (OH) _ {2} + 2NaOH + H_ {2} O \ \ rightleftarrows \ Na_ {2} [Hf (OH) _ {6}]}}}

Literature

Chemical Encyclopedia / Editorial Board: Knunyants I.L. et al. - M .: Soviet Encyclopedia, 1988. - T. 1. - 623 p.
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 .
Ripan R., Chetyanu I. Inorganic chemistry. Chemistry of metals. - M .: Mir, 1972. - T. 2. - 871 p.