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Properties of substance:
selenium
Group of substances:
inorganic
Physical appearance:
gray trigonal crystals
Empirical formula (Hill's system for organic substances):
Se
Structural formula as text:
Se
Molar/atomic mass: 78.96
Melting point (°C):
217
Boiling point (°C):
685
Solubility (g/100 g of solvent):
carbon disulphide
: 0.065 (20°C) [
Ref.
]
hydrogen fluoride
: insoluble [
Ref.
]
iodine liquid
: soluble [
Ref.
]
methylene iodide
: 1.3 (12°C) [
Ref.
]
nickel tetracarbonyl
: insoluble [
Ref.
]
Numerical data:
Year of discovery: 1817
Hardness on the Mohs’ scale: 2
Density:
4.79 (20°C, g/cm
3
)
Reactions of synthesis:
[
Ref.1
,
Ref.2
]
H
2
SeO
3
+ 2SO
2
+ H
2
O → Se + 2H
2
SO
4
Reactions:
[
Ref.1
,
Ref.2
]
Se + 3F
2
→ SeF
6
[
Ref.1
]
2K + Se → K
2
Se
[
Ref.1
]
Se + 4HNO
3
→ H
2
SeO
3
+ 4NO
2
+ H
2
O
H
2
SeO
3
→ SeO
2
+ H
2
O
[
Ref.1
]
Se + O
2
→ SeO
2
Half-life:
65
34
Se = 33 ms (β
+
(100%))
66
34
Se = 33 ms (β
+
(100%))
67
34
Se = 133 ms (β
+
(100%))
68
34
Se = 35.5 s (β
+
(100%))
69
34
Se = 34.7 s (β
+
(100%), β
+
p (0.045%))
69m
34
Se = 2.0 μs (internal transition (100%))
69n
34
Se = 955 ns (internal transition (100%))
70
34
Se = 41.1 min (β
+
(100%))
71
34
Se = 4.74 min (β
+
(100%))
71m
34
Se = 5.6 μs (internal transition (100%))
71n
34
Se = 19.0 μs (internal transition (100%))
72
34
Se = 8.40 d (electron capture (100%))
73
34
Se = 7.15 h (β
+
(100%))
73m
34
Se = 39.8 min (β
+
(27.4%), internal transition (72.6%))
74
34
Se = stable ( (isotopic abundance 0,89%))
75
34
Se = 119.779 d (electron capture (100%))
76
34
Se = stable ( (isotopic abundance 9,37%))
77
34
Se = stable ( (isotopic abundance 7,63%))
77m
34
Se = 17.36 s (internal transition (100%))
78
34
Se = stable ( (isotopic abundance 23,77%))
79
34
Se = 335 000 y (β
-
(100%))
79m
34
Se = 3.92 min (internal transition (about 100%), β
-
(0.056%))
80
34
Se = stable ( (isotopic abundance 49,61%))
81
34
Se = 18.45 min (β
-
(100%))
81m
34
Se = 57.28 min (internal transition (about 100%), β
-
(0.051%))
82
34
Se = 9.7 · 10
19
y (2β
-
(100%) (isotopic abundance 8,73%))
83
34
Se = 22.3 min (β
-
(100%))
83m
34
Se = 70.1 s (β
-
(100%))
84
34
Se = 3.26 min (β
-
(100%))
85
34
Se = 31.7 s (β
-
(100%))
86
34
Se = 14.3 s (β
-
(100%))
87
34
Se = 5.50 s (β
-
(100%), β
-
n (0.2%))
88
34
Se = 1.53 s (β
-
(100%), β
-
n (0.67%))
89
34
Se = 410 ms (β
-
(100%), β
-
n (7.8%))
90
34
Se = 210 ms (β
-
(100%), β
-
n (?))
91
34
Se = 270 ms (β
-
(100%), β
-
n (21%))
Vapour pressure (Torr):
0.000000001 (67°C)
0.00000001 (84°C)
0.0000001 (104°C)
0.000001 (121°C)
0.00001 (144°C)
0.0001 (169°C)
0.001 (198°C)
0.0055 (217.4°C)
0.01 (231°C)
0.1 (287°C)
1 (350°C)
10 (428°C)
42 (500°C)
100 (534°C)
550 (660°C)
Surface tension (mN/m):
92.5 (217°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)):
42.1 (s)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
25.4 (s)
Molar enthalpy (heat) of fusion Δ
fus
H (kJ/mol):
6.7
Enthalpy (heat) of vaporization Δ
vap
H (kJ/mol):
29
Standard molar enthalpy (heat) of formation Δ
f
H
0
(298.15 K, kJ/mol):
223.4 (g)
Standard molar entropy S
0
(298.15 K, J/(mol·K)):
176.62 (g)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
20.82 (g)
References:
Seidell A. Solubilities of inorganic and metal organic compounds. - 3ed., vol.1. - New York: D. Van Nostrand Company, 1940. - pp. 1485-1486
Вредные химические вещества: Неорганические соединения элементов V-VIII групп. Справочник. - Л., 1989. - pp. 269-270 [Russian]
Гринвуд Н., Эрншо А. Химия элементов. - Т.2. - М.: БИНОМ. Лаборатория знаний, 2008. - pp. 101-111 [Russian]
Гурвич Я.А. Справочник молодого аппаратчика-химика. - М.: Химия, 1991. - pp. 48, 51 [Russian]
Девяткин В.В., Ляхова Ю.М. Химия для любознательных, или о чем не узнаешь на уроке. - Ярославль: Академия Холдинг, 2000. - pp. 33 [Russian]
Некрасов Б.В. Основы общей химии. - Т.1. - М.: Химия, 1973. - pp. 355-356 [Russian]
Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 95-96 [Russian]
Редкие и рассеянные элементы. Химия и технология. - Кн. 3. - М.: Мисис, 2003. - pp. 237-241, 266 [Russian]
Справочник по растворимости. - Т.1, Кн.1. - М.-Л.: ИАН СССР, 1961. - pp. 617 [Russian]
Энциклопедия для детей. - Т.17: Химия. - М.: Аванта+, 2004. - pp. 239 [Russian]
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© Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru
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