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Properties of substance:

neptunium alpha form

Group of substances:

inorganic

Physical appearance:

rhombic metal

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

Np

Structural formula as text:

Np

Molar/atomic mass: 237.05

Melting point (°C):

637

Boiling point (°C):

4100

Solubility (g/100 g of solvent):

water: insoluble [Ref.]

Numerical data:

Year of discovery: 1940

Density:

20.45 (25°C, g/cm3)

Electrode potential:

Np3+ + 3e- → Np, E = -1.856 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)):

50.6 (s)

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

29.5 (s)

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

5.2

ΔHsublimation (kJ/mol):

422

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

464 (g)

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

197.6 (g)

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

20.8 (g)

References:

  1. Гурвич Я.А. Справочник молодого аппаратчика-химика. - М.: Химия, 1991. - pp. 51 [Russian]
  2. Ефимов А.И. и др. Свойства неорганических соединений. Справочник. - Л.: Химия, 1983. - pp. 170-171 [Russian]
  3. Михайлов В.А. Аналитическая химия нептуния. - М.: Наука, 1971. - pp. 13 [Russian]
  4. Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 86 [Russian]

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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru