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Properties of substance:
lanthanum
Group of substances:
inorganic
Physical appearance:
hexagonal metal
Empirical formula (Hill's system for organic substances):
La
Structural formula as text:
La
Molar/atomic mass: 138.91
Melting point (°C):
920
Boiling point (°C):
3950
Solubility (g/100 g of solvent):
gallium
: 1 (500°C) [
Ref.
]
mercury
: 0.0045 (0°C) [
Ref.
]
mercury
: 0.0096 (25°C) [
Ref.
]
mercury
: 0.0171 (50°C) [
Ref.
]
water
: reaction [
Ref.
]
Numerical data:
Year of discovery: 1839
Superconducting temperature (K): 4.88 (α-form)
Superconducting temperature (K): 6 (β-form)
Density:
6.16 (20°C, g/cm
3
)
Reactions of synthesis:
[
Ref.1
]
LaCl
3
+ 3K → La + 3KCl
[
Ref.1
]
2LaCl
3
→ 2La + 3Cl
2
Half-life:
117
57
La = 21.7 ms ()
117m
57
La = 10 ms ()
120
57
La = 2.8 s (β
+
(100%), β
+
p (?))
121
57
La = 5.3 s (β
+
(100%), β
+
p (?))
122
57
La = 8.6 s (β
+
(100%), β
+
p (?))
123
57
La = 17 s (β
+
(100%))
124
57
La = 29.21 s (β
+
(100%))
124m
57
La = 21 s (β
+
(100%))
125
57
La = 64.8 s (β
+
(100%))
125m
57
La = 390 ms (internal transition (100%))
126
57
La = 54 s (β
+
(100%))
126m
57
La = 20 s (β
+
(100%))
127
57
La = 5.1 min (β
+
(100%))
127m
57
La = 3.7 min (β
+
(about 100%))
128
57
La = 5.18 min (β
+
(100%))
129
57
La = 11.6 min (β
+
(100%))
129m
57
La = 560 ms (internal transition (100%))
130
57
La = 8.7 min (β
+
(100%))
130m
57
La = 760 ns (internal transition (100%))
130n
57
La = 33 ns (internal transition (100%))
131
57
La = 59 min (β
+
(100%))
131m
57
La = 170 μs (internal transition (100%))
132
57
La = 4.8 h (β
+
(100%))
132m
57
La = 24.3 min (internal transition (76%), β
+
(24%))
133
57
La = 3.192 h (β
+
(100%))
134
57
La = 6.45 min (β
+
(100%))
134m
57
La = 29 μs (internal transition (100%))
135
57
La = 19.5 h (β
+
(100%))
136
57
La = 9.87 min (β
+
(100%))
136m
57
La = 114 ms (internal transition (100%))
137
57
La = 60 000 y (electron capture (100%))
137m
57
La = 342 ns (internal transition (100%))
138
57
La = 102 000 000 000 y (β
+
(65.6%), β
-
(34.4%) (isotopic abundance 0,08881%))
138m
57
La = 116 ns (internal transition (100%))
138n
57
La = 2.0 μs (internal transition (100%))
139
57
La = stable ( (isotopic abundance 99,91119%))
139m
57
La = 315 ns (internal transition (100%))
140
57
La = 40.285 h (β
-
(100%))
141
57
La = 3.92 h (β
-
(100%))
142
57
La = 91.1 min (β
-
(100%))
142m
57
La = 870 ns (internal transition (100%))
143
57
La = 14.2 min (β
-
(100%))
144
57
La = 40.8 s (β
-
(100%))
145
57
La = 24.8 s (β
-
(100%))
146
57
La = 6.27 s (β
-
(100%))
146m
57
La = 10.0 s (β
-
(100%))
147
57
La = 4.06 s (β
-
(100%), β
-
n (0.041%))
148
57
La = 1.35 s (β
-
(100%), β
-
n (0.15%))
149
57
La = 1.07 s (β
-
(100%), β
-
n (1.43%))
150
57
La = 504 ms (β
-
(100%), β
-
n (2.7%))
151
57
La = 465 ms (β
-
(100%), β
-
n )
152
57
La = 287 ms (β
-
(100%), β
-
n)
153
57
La = 245 ms (β
-
(100%), β
-
n)
154
57
La = 161 ms (β
-
(100%), β
-
n)
155
57
La = 101 ms (β
-
(100%), β
-
n)
156
57
La = 84 ms (β
-
(100%), β
-
n)
Vapour pressure (Torr):
1 (2156°C)
10 (2474°C)
100 (2387°C)
Electrode potential:
La
3+
+ 3e
-
→ La, E = -2.522 V (water, 25°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)):
57.3 (s)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
27.6 (s)
Molar enthalpy (heat) of fusion Δ
fus
H (kJ/mol):
6.7
Enthalpy (heat) of vaporization Δ
vap
H (kJ/mol):
413
Standard molar enthalpy (heat) of formation Δ
f
H
0
(298.15 K, kJ/mol):
430 (g)
Standard molar entropy S
0
(298.15 K, J/(mol·K)):
182.3 (g)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
22.8 (g)
References:
Seidell A. Solubilities of inorganic and metal organic compounds. - 3ed., vol.1. - New York: D. Van Nostrand Company, 1940. - pp. 887
Гурвич Я.А. Справочник молодого аппаратчика-химика. - М.: Химия, 1991. - pp. 51 [Russian]
Некрасов Б.В. Основы общей химии. - Т.2. - М.: Химия, 1973. - pp. 72-73 [Russian]
Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 75 [Russian]
Справочник по растворимости. - Т.1, Кн.1. - М.-Л.: ИАН СССР, 1961. - pp. 595 [Russian]
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© Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru
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