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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):
Cr
2
K
2
O
7
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/cm
3
)
Reactions of synthesis:
[
Ref.1
]
Na
2
Cr
2
O
7
+ 2KCl → 2NaCl + K
2
Cr
2
O
7
Reactions:
[
Ref.1
,
Ref.2
]
K
2
Cr
2
O
7
+ 7H
2
C
2
O
4
+ 2K
2
C
2
O
4
→ 2K
3
[Cr(C
2
O
4
)
3
]*3H
2
O + 6CO
2
+ H
2
O
[
Ref.1
,
Ref.2
]
K
2
Cr
2
O
7
+ 2H
2
SO
4
→ 2CrO
3
+ 2KHSO
4
+ H
2
O
[
Ref.1
]
K
2
Cr
2
O
7
+ 14HCl → 2KCl + 2CrCl
3
+ 3Cl
2
+ 7H
2
O
[
Ref.1
]
K
2
Cr
2
O
7
+ 4NaCl + 3H
2
SO
4
→ 2CrO
2
Cl
2
+ K
2
SO
4
+ 2Na
2
SO
4
+ 3H
2
O
Refractive index (n
D
):
1.738 (20°C)
Viscosity (mPa·s):
13.2 (400°C)
9.8 (450°C)
7 (500°C)
Standard molar enthalpy (heat) of formation Δ
f
H
0
(298.15 K, kJ/mol):
-2033 (s)
Standard molar Gibbs energy of formation Δ
f
G
0
(298.15 K, kJ/mol):
-1866 (s)
Standard molar entropy S
0
(298.15 K, J/(mol·K)):
291.2 (s)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
219.7 (s)
Molar enthalpy (heat) of fusion Δ
fus
H (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:
Armarego W. L. F. Purification of Laboratory Chemicals. - 7ed. - 2013. - pp. 600
Seidell A. Solubilities of inorganic and metal organic compounds. - 3ed., vol.1. - New York: D. Van Nostrand Company, 1940. - pp. 801-803
Девяткин В.В., Ляхова Ю.М. Химия для любознательных, или о чем не узнаешь на уроке. - Ярославль: Академия Холдинг, 2000. - pp. 109-110 [Russian]
Некрасов Б.В. Основы общей химии. - Т.1. - М.: Химия, 1973. - pp. 372 [Russian]
РЖ Токсикология, Отдельный выпуск. - 1979. - №2. - pp. 5 [Russian]
Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 70 [Russian]
Реми Г. Курс неорганической химии. - Т.2. - М., 1966. - pp. 175 [Russian]
Справочник химика. - Т. 2. - Л.-М.: Химия, 1964. - pp. 88-89 [Russian]
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