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Properties of substance:

tungstic acid

Group of substances:

inorganic

Physical appearance:

orange-yellow rhombic crystals

Empirical formula (Hill's system for organic substances):

H2O4W

Structural formula as text:

H2WO4

Molar/atomic mass: 249.86

Decomposition temperature (°C):

100

Solubility (g/100 g of solvent):

water: insoluble [Ref.]

Density:

5.5 (20°C, g/cm3)

Reactions of synthesis:

  1. [Ref.1]
    WOCl4 + 3H2O → H2WO4 + 4HCl

Dissociation:

pKa (1) = 2.2 (25°C, water)
pKa (2) = 3.7 (25°C, water)

Standard molar enthalpy (heat) of formation ΔfH0 (298.15 K, kJ/mol):

-1132 (s)

Standard molar Gibbs energy of formation ΔfG0 (298.15 K, kJ/mol):

-1036.4 (s)

Standard molar entropy S0 (298.15 K, J/(mol·K)):

117.2 (s)

Molar heat capacity at constant pressure Cp (298.15 K, J/(mol·K)):

119.9 (s)

References:

  1. Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 60 [Russian]
  2. Химия и технология редких и рассеянных элементов. - Ч. 3. - М.: Высшая школа, 1976. - pp. 225-226 [Russian]

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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru