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Properties of substance:

potassium

Group of substances:

inorganic

Physical appearance:

cubic metal

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

K

Structural formula as text:

K

Molar/atomic mass: 39.1

Melting point (°C):

63.55

Boiling point (°C):

776

Solubility (g/100 g of solvent):

ammonia liquid : 45.56 (-50.38°C) [Ref.]
ammonia liquid : 46.37 (-33.2°C) [Ref.]
ammonia liquid : 49.05 (0°C) [Ref.]
aniline: soluble [Ref.]
diethylamine: insoluble [Ref.]
ethanol: reaction [Ref.]
ethylenediamine: 0.045 (20°C) [Ref.]
gallium: 0.000004 (32°C) [Ref.]
gallium: 4 (500°C) [Ref.]
hexamethylphosphoric triamide: very soluble [Ref.]
mercury: 0.31 (0°C) [Ref.]
mercury: 0.8 (18°C) [Ref.]
mercury: 0.48 (20°C) [Ref.]
mercury: 0.54 (25°C) [Ref.]
mercury: 1.03 (60°C) [Ref.]
mercury: 2.05 (90°C) [Ref.]
mercury: 2.12 (99.8°C) [Ref.]
methylamine: 0.056 [Ref.]
potassium chloride fused: 4.14 (800°C) [Ref.]
potassium fluoride fused: 16.97 (948°C) [Ref.]
triethylamine: insoluble [Ref.]
water: reaction [Ref.]

Properties of solutions:

6,3% (wt.), solvent - ammonia liquid
  Density (g/cm3) = 0.6721 (-33,2°)
12,4% (wt.), solvent - ammonia liquid
  Density (g/cm3) = 0.6583 (-33,2°)
31,67% (wt.), solvent - ammonia liquid
  Density (g/cm3) = 0.6282 (-33,2°)
34,79% (wt.), solvent - ammonia liquid
  Boiling point (°C) = -0.4
0,306% (wt.), solvent - mercury
  Density (g/cm3) = 13.2365 (20°)
0,4528% (wt.), solvent - mercury
  Density (g/cm3) = 13.0886 (20°)

Numerical data:

Year of discovery: 1807
Hardness on the Mohs’ scale: 0.5

Density:

0.892 (-173°C, g/cm3)
0.862 (20°C, g/cm3)
0.8514 (62.1°C, g/cm3)
0.826 (64°C, d4)
0.819 (100°C, g/cm3)
0.807 (150°C, g/cm3)
0.795 (200°C, g/cm3)
0.773 (300°C, g/cm3)
0.75 (400°C, g/cm3)
0.727 (500°C, g/cm3)
0.704 (600°C, g/cm3)
0.681 (700°C, g/cm3)

Reactions of synthesis:

  1. [Ref.1]
    Na + KOH → K + NaOH
  2. [Ref.1]
    Na + KCl → K + NaCl

Reactions:

  1. [Ref.1]
    2K + F2 → 2KF
  2. [Ref.1]
    2K + Cl2 → 2KCl
  3. [Ref.1]
    2K + Br2 → 2KBr
  4. [Ref.1]
    2K + S → K2S
  5. [Ref.1]
    2K + Se → K2Se
  6. [Ref.1]
    2K + Te → K2Te
  7. [Ref.1]
    2K + Te → K2Te
  8. [Ref.1]
    K + O2 → KO2
  9. [Ref.1]
    2K + H2 → 2KH
  10. [Ref.1]
    2K + 2H2O → 2KOH + H2
  11. Yeild 60%. [Ref.1]
    2(((CH3)3Si)2CH)2AlCl + 2K → (((CH3)3Si)2CH)2AlAl(CH(Si(CH3)3)2)2 + 2KCl
  12. [Ref.1]
    3K + As → K3As
  13. [Ref.1]
    K + 8C → KC8
  14. [Ref.1]
    K + 16C → KC16
  15. [Ref.1]
    2K + C2H4 → K2C2 + 2H2
  16. [Ref.1]
    2K + 2NH3 → 2KNH2 + H2
  17. [Ref.1]
    2C6H5NH2 + 2K → 2C6H5NHK + H2
  18. [Ref.1, Ref.2]
    K + O2 → KO2
  19. [Ref.1aster]
    LaCl3 + 3K → La + 3KCl
  20. [Ref.1]
    2K + 2C2H2 → 2KHC2 + H2

Half-life:

3519K = 178 ms (β+ (100%); mass excess -11169 keV)
3619K = 342 ms (β+ (100%); mass excess -17426 keV)
3719K = 1.226 s (β+ (100%); mass excess -24800 keV)
3819K = 7.636 min (β+ (100%); mass excess -28800,7 keV)
38m19K = 923.9 ms (β+ (100%); mass excess -28670,2 keV)
38n19K = 21.98 μs (internal transition (100%); mass excess -25342,7 keV)
3919K = stable (mass excess -33807,01 keV (isotopic abundance 93,2581%))
4019K = 1 265 000 000 y (β- (89.33%), β+ (10.67%); mass excess -33535,2 keV (isotopic abundance 0,0117%))
40m19K = 336 ns (internal transition (100%); mass excess -31891,56 keV)
4119K = stable (mass excess -35559,07 keV (isotopic abundance 6,7302%))
4219K = 12.360 h (β- (100%); mass excess -35021,56 keV)
4319K = 22.3 h (β- (100%); mass excess -36593 keV)
4419K = 22.13 min (β- (100%))
4519K = 17.3 min (β- (100%))
4619K = 105 s (β- (100%))
4719K = 17.50 s (β- (100%))
4819K = 6.8 s (β- (100%))
4919K = 1.26 s (β- (100%), β-n (86%))
5019K = 472 ms (β- (100%), β-n (29%))
5119K = 365 ms (β- (100%), β-n (47%))
5219K = 105 ms (β- (100%), β-n (65%))
5319K = 30 ms (β- (100%), β-n (67%))
5419K = 10 ms (β-. β-n)

Vapour pressure (Torr):

0.000012 (86.4°C)
0.00001797 (99.5°C)
0.0001 (117.4°C)
0.00049 (149°C)
0.001006 (162.7°C)
0.01 (209.7°C)
0.05 (249.5°C)
0.1 (269°C)
1 (344°C)
10 (446°C)
100 (589°C)

Electrode potential:

K+ + e- → K, E = -3.36 V (formic acid, 25°C)
K+ + e- → K, E = -3.16 V (acetonitrile, 25°C)
K+ + e- → K, E = -2.92 V (water, 25°C)
K+ + e- → K, E = -2.92 V (methanol, 25°C)
K+ + e- → K, E = -2.847 V (ethanol, 25°C)
K+ + e- → K, E = -1.98 V (ammonia liquid , -50°C)

Viscosity (mPa·s):

0.515 (69.5°C)
0.466 (100°C)
0.324 (200°C)
0.191 (400°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)):

71.45 (s)

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

32.72 (s)

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

2.38

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

79.2

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

89.16 (g)

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

60.67 (g)

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

160.23 (g)

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

20.79 (g)

References:

  1. Seidell A. Solubilities of inorganic and metal organic compounds. - 3ed., vol.1. - New York: D. Van Nostrand Company, 1940. - pp. 682
  2. Алабышев А.Ф., Грачев К.Я., Зарецкий С.А., Лантратов М.Ф. Натрий и калий (получение, свойства и применение). - Л.: ГНТИХЛ, 1959. - pp. 261-379 [Russian]
  3. Герасимов Я.И., Древинг В.П., Еремин Е.Н.. Киселев А.В., Лебедев В.П., Панченков Г.М., Шлыгин А.И. Курс физической химии. - Т.2. - М.: Химия, 1973. - pp. 528 [Russian]
  4. Гринвуд Н., Эрншо А. Химия элементов. - Т.1. - М.: БИНОМ. Лаборатория знаний, 2008. - pp. 75, 81, 83 [Russian]
  5. Гурвич Я.А. Справочник молодого аппаратчика-химика. - М.: Химия, 1991. - pp. 50 [Russian]
  6. Карапетьянц М.Х., Дракин С.И. Общая и неорганическая химия. - М.: Химия, 1981. - pp. 307 [Russian]
  7. Коровин Н.В., Масленникова Г.Н., Мингулина Э.И., Филиппов Э.Л. Курс общей химии. - М.: Высшая школа, 1990. - pp. 260 [Russian]
  8. Неорганические синтезы. - Сб. 1. - М.: ИИЛ, 1951. - pp. 10 [Russian]
  9. Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 67 [Russian]
  10. Свойства элементов. - под общей редакцией Дрица М.Е. - М.: Металлургия, 1985. - pp. 42-49 [Russian]
  11. Справочник по растворимости. - Т.1, Кн.1. - М.-Л.: ИАН СССР, 1961. - pp. 591 [Russian]
  12. Энциклопедия для детей. - Т.17: Химия. - М.: Аванта+, 2004. - pp. 186 [Russian]

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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru