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Properties of substance:

hafnium

Group of substances:

inorganic

Physical appearance:

hexagonal metal

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

Hf

Structural formula as text:

Hf

Molar/atomic mass: 178.49

Melting point (°C):

2220

Boiling point (°C):

4600

Solubility (g/100 g of solvent):

mercury: insoluble [Ref.]
water: insoluble [Ref.]

Numerical data:

Year of discovery: 1923

Density:

13.31 (20°C, g/cm3)

Vapour pressure (Torr):

0.1 (2870°C)
1 (3205°C)
10 (3700°C)
100 (4440°C)

Electrode potential:

Hf4+ + 4e- → Hf, E = -1.7 V (water, 25°C)

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

0 (s)

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

0 (s)

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

43.55 (s)

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

25.7 (s)

Molar enthalpy (heat) of fusion ΔfusH (kJ/mol):

21

Enthalpy (heat) of vaporization ΔvapH (kJ/mol):

569

References:

  1. Гурвич Я.А. Справочник молодого аппаратчика-химика. - М.: Химия, 1991. - pp. 48, 50 [Russian]
  2. Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 61 [Russian]
  3. Шека И.А., Карлышева К.Ф. Химия гафния. - Киев: Наукова думка, 1973 [Russian]

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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru