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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/cm
3
)
Vapour pressure (Torr):
0.1 (2870°C)
1 (3205°C)
10 (3700°C)
100 (4440°C)
Electrode potential:
Hf
4+
+ 4e
-
→ Hf, E = -1.7 V (water, 25°C)
Standard molar enthalpy (heat) of formation Δ
f
H
0
(298.15 K, kJ/mol):
0 (s)
Standard molar Gibbs energy of formation Δ
f
G
0
(298.15 K, kJ/mol):
0 (s)
Standard molar entropy S
0
(298.15 K, J/(mol·K)):
43.55 (s)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
25.7 (s)
Molar enthalpy (heat) of fusion Δ
fus
H (kJ/mol):
21
Enthalpy (heat) of vaporization Δ
vap
H (kJ/mol):
569
References:
Гурвич Я.А. Справочник молодого аппаратчика-химика. - М.: Химия, 1991. - pp. 48, 50 [Russian]
Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 61 [Russian]
Шека И.А., Карлышева К.Ф. Химия гафния. - Киев: Наукова думка, 1973 [Russian]
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© Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru