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Properties of substance:

potassium dichromate

Group of substances:

inorganic

Physical appearance:

orange-red triclinic crystals

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

Cr2K2O7

Structural formula as text:

K2Cr2O7

Molar/atomic mass: 294.18

Melting point (°C):

398

Decomposition temperature (°C):

610

CAS №: 7778-50-9

Solubility (g/100 g of solvent):

ammonia liquid : insoluble [Ref.]
deuterium oxide: 3.563 (5°C) [Ref.]
deuterium oxide: 6.067 (15°C) [Ref.]
deuterium oxide: 9.896 (25°C) [Ref.]
deuterium oxide: 14.991 (35°C) [Ref.]
ethanol: insoluble [Ref.]
ethyl acetate: insoluble [Ref.]
ethylene carbonate: soluble (40°C) [Ref.]
hydrazine: soluble with reaction 1 [Ref.]
hydrogen fluoride : reaction [Ref.]
sulfur dioxide: soluble [Ref.]
water: 4.7 (0°C) [Ref.]
water: 7.8 (10°C) [Ref.]
water: 12.5 (20°C) [Ref.]
water: 15 (25°C) [Ref.]
water: 18.2 (30°C) [Ref.]
water: 25.9 (40°C) [Ref.]
water: 45.6 (60°C) [Ref.]
water: 73 (80°C) [Ref.]
water: 100 (100°C) [Ref.]

Density:

2.68 (20°C, g/cm3)

Reactions of synthesis:

  1. [Ref.1]
    Na2Cr2O7 + 2KCl → 2NaCl + K2Cr2O7

Reactions:

  1. [Ref.1aster]
    K2Cr2O7 + 7H2C2O4 + 2K2C2O4 → 2K3[Cr(C2O4)3]*3H2O + 6CO2 + H2O
  2. [Ref.1aster, Ref.2aster]
    K2Cr2O7 + 2H2SO4 → 2CrO3 + 2KHSO4 + H2O
  3. [Ref.1]
    K2Cr2O7 + 14HCl → 2KCl + 2CrCl3 + 3Cl2 + 7H2O

Refractive index (nD):

1.738 (20°C)

Viscosity (mPa·s):

13.2 (400°C)
9.8 (450°C)
7 (500°C)

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

-2033 (s)

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

-1866 (s)

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

291.2 (s)

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

219.7 (s)

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

35.6

Spectral properties of the substance:

Ultraviolet/visible spectrum (maximum in nm, layer thickness 1 cm, in parentheses - extinction) = 350 (75)

References:

  1. Armarego W. L. F. Purification of Laboratory Chemicals. - 7ed. - 2013. - pp. 600
  2. Seidell A. Solubilities of inorganic and metal organic compounds. - 3ed., vol.1. - New York: D. Van Nostrand Company, 1940. - pp. 801-803
  3. Девяткин В.В., Ляхова Ю.М. Химия для любознательных, или о чем не узнаешь на уроке. - Ярославль: Академия Холдинг, 2000. - pp. 109-110 [Russian]
  4. Некрасов Б.В. Основы общей химии. - Т.1. - М.: Химия, 1973. - pp. 372 [Russian]
  5. РЖ Токсикология, Отдельный выпуск. - 1979. - №2. - pp. 5 [Russian]
  6. Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 70 [Russian]
  7. Реми Г. Курс неорганической химии. - Т.2. - М., 1966. - pp. 175 [Russian]
  8. Справочник химика. - Т. 2. - Л.-М.: Химия, 1964. - pp. 88-89 [Russian]
  9. Химическая технология неорганических веществ. - Кн.2, под ред. Ахметова Т.Г. - М.: Высшая школа, 2002. - pp. 179-188 [Russian]

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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru