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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/cm
3
) = 0.6721 (-33,2°)
12,4% (wt.), solvent - ammonia liquid
Density (g/cm
3
) = 0.6583 (-33,2°)
31,67% (wt.), solvent - ammonia liquid
Density (g/cm
3
) = 0.6282 (-33,2°)
34,79% (wt.), solvent - ammonia liquid
Boiling point (°C) = -0.4
0,306% (wt.), solvent - mercury
Density (g/cm
3
) = 13.2365 (20°)
0,4528% (wt.), solvent - mercury
Density (g/cm
3
) = 13.0886 (20°)
Numerical data:
Year of discovery: 1807
Hardness on the Mohs’ scale: 0.5
Density:
0.892 (-173°C, g/cm
3
)
0.862 (20°C, g/cm
3
)
0.8514 (62.1°C, g/cm
3
)
0.826 (64°C, d
4
)
0.819 (100°C, g/cm
3
)
0.807 (150°C, g/cm
3
)
0.795 (200°C, g/cm
3
)
0.773 (300°C, g/cm
3
)
0.75 (400°C, g/cm
3
)
0.727 (500°C, g/cm
3
)
0.704 (600°C, g/cm
3
)
0.681 (700°C, g/cm
3
)
Reactions of synthesis:
[
Ref.1
]
Na + KOH → K + NaOH
[
Ref.1
]
Na + KCl → K + NaCl
Reactions:
[
Ref.1
]
2K + F
2
→ 2KF
[
Ref.1
]
2K + Cl
2
→ 2KCl
[
Ref.1
]
2K + Br
2
→ 2KBr
[
Ref.1
]
2K + S → K
2
S
[
Ref.1
]
2K + Se → K
2
Se
[
Ref.1
]
2K + Te → K
2
Te
[
Ref.1
]
2K + Te → K
2
Te
[
Ref.1
]
K + O
2
→ KO
2
[
Ref.1
]
2K + H
2
→ 2KH
[
Ref.1
]
2K + 2H
2
O → 2KOH + H
2
Yeild 60%. [
Ref.1
]
2(((CH
3
)
3
Si)
2
CH)
2
AlCl + 2K → (((CH
3
)
3
Si)
2
CH)
2
AlAl(CH(Si(CH
3
)
3
)
2
)
2
+ 2KCl
[
Ref.1
]
3K + As → K
3
As
[
Ref.1
]
K + 8C → KC
8
[
Ref.1
]
K + 16C → KC
16
[
Ref.1
]
2K + C
2
H
4
→ K
2
C
2
+ 2H
2
[
Ref.1
]
2K + 2NH
3
→ 2KNH
2
+ H
2
[
Ref.1
]
2C
6
H
5
NH
2
+ 2K → 2C
6
H
5
NHK + H
2
[
Ref.1
,
Ref.2
]
K + O
2
→ KO
2
[
Ref.1
]
LaCl
3
+ 3K → La + 3KCl
[
Ref.1
]
2K + 2C
2
H
2
→ 2KHC
2
+ H
2
Half-life:
35
19
K = 178 ms (β
+
(100%); mass excess -11169 keV)
36
19
K = 342 ms (β
+
(100%); mass excess -17426 keV)
37
19
K = 1.226 s (β
+
(100%); mass excess -24800 keV)
38
19
K = 7.636 min (β
+
(100%); mass excess -28800,7 keV)
38m
19
K = 923.9 ms (β
+
(100%); mass excess -28670,2 keV)
38n
19
K = 21.98 μs (internal transition (100%); mass excess -25342,7 keV)
39
19
K = stable (mass excess -33807,01 keV (isotopic abundance 93,2581%))
40
19
K = 1 265 000 000 y (β
-
(89.33%), β
+
(10.67%); mass excess -33535,2 keV (isotopic abundance 0,0117%))
40m
19
K = 336 ns (internal transition (100%); mass excess -31891,56 keV)
41
19
K = stable (mass excess -35559,07 keV (isotopic abundance 6,7302%))
42
19
K = 12.360 h (β
-
(100%); mass excess -35021,56 keV)
43
19
K = 22.3 h (β
-
(100%); mass excess -36593 keV)
44
19
K = 22.13 min (β
-
(100%))
45
19
K = 17.3 min (β
-
(100%))
46
19
K = 105 s (β
-
(100%))
47
19
K = 17.50 s (β
-
(100%))
48
19
K = 6.8 s (β
-
(100%))
49
19
K = 1.26 s (β
-
(100%), β
-
n (86%))
50
19
K = 472 ms (β
-
(100%), β
-
n (29%))
51
19
K = 365 ms (β
-
(100%), β
-
n (47%))
52
19
K = 105 ms (β
-
(100%), β
-
n (65%))
53
19
K = 30 ms (β
-
(100%), β
-
n (67%))
54
19
K = 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 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)):
71.45 (s)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
32.72 (s)
Molar enthalpy (heat) of fusion Δ
fus
H (kJ/mol):
2.38
Enthalpy (heat) of vaporization Δ
vap
H (kJ/mol):
79.2
Standard molar enthalpy (heat) of formation Δ
f
H
0
(298.15 K, kJ/mol):
89.16 (g)
Standard molar Gibbs energy of formation Δ
f
G
0
(298.15 K, kJ/mol):
60.67 (g)
Standard molar entropy S
0
(298.15 K, J/(mol·K)):
160.23 (g)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
20.79 (g)
References:
Seidell A. Solubilities of inorganic and metal organic compounds. - 3ed., vol.1. - New York: D. Van Nostrand Company, 1940. - pp. 682
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]
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]
Гринвуд Н., Эрншо А. Химия элементов. - Т.1. - М.: БИНОМ. Лаборатория знаний, 2008. - pp. 75, 81, 83 [Russian]
Гурвич Я.А. Справочник молодого аппаратчика-химика. - М.: Химия, 1991. - pp. 50 [Russian]
Карапетьянц М.Х., Дракин С.И. Общая и неорганическая химия. - М.: Химия, 1981. - pp. 307 [Russian]
Коровин Н.В., Масленникова Г.Н., Мингулина Э.И., Филиппов Э.Л. Курс общей химии. - М.: Высшая школа, 1990. - pp. 260 [Russian]
Неорганические синтезы. - Сб. 1. - М.: ИИЛ, 1951. - pp. 10 [Russian]
Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 67 [Russian]
Свойства элементов. - под общей редакцией Дрица М.Е. - М.: Металлургия, 1985. - pp. 42-49 [Russian]
Справочник по растворимости. - Т.1, Кн.1. - М.-Л.: ИАН СССР, 1961. - pp. 591 [Russian]
Энциклопедия для детей. - Т.17: Химия. - М.: Аванта+, 2004. - pp. 186 [Russian]
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© Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru