Introduction
Group: 9 or VIII B
Atomic Weight: 58.9332
Period: 4
CAS Number: 7440-48-4
Classification
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)
Description • Uses/Function
Discovered by Brandt about 1735. Cobalt occurs in the mineral cobaltite, smaltite, and erythrite, and is often associatedwith nickel, silver, lead, copper, and iron ores, from which it is most frequently obtained as a by-product. It is also present in meteorites. Importantore deposits are found in Zaire, Morocco, and Canada. The U.S. Geological Survey has announced that the bottom of the north central Pacific Oceanmay have cobalt-rich deposits at relatively shallow depths in waters close to the Hawaiian Islands and other U.S. Pacific territories. Cobalt is a brittle,hard metal, closely resembling iron and nickel in appearance. It has a magnetic permeability of about two thirds that of iron. Cobalt tends to exist asa mixture of two allotropes over a wide temperature range; the beta-form predominates below 400°C, and the alpha above that temperature. The transformationis sluggish and accounts in part for the wide variation in reported data on physical properties of cobalt. It is alloyed with iron, nickel and other metalsto make Alnico, an alloy of unusual magnetic strength with many important uses. Stellite alloys, containing cobalt, chromium, and tungsten, are usedfor high-speed, heavy-duty, high temperature cutting tools, and for dies. Cobalt is also used in other magnet steels and stainless steels, and in alloysused in jet turbines and gas turbine generators. The metal is used in electroplating because of its appearance, hardness, and resistance to oxidation.The salts have been used for centuries for the production of brilliant and permanent blue colors in porcelain, glass, pottery, tiles, and enamels. It isthe principal ingredient in Sevre’s and Thenard’s blue. A solution of the chloride (CoCl2 · 6H2O) is used as sympathetic ink. The cobalt ammines areof interest; the oxide and the nitrate are important. Cobalt carefully used in the form of the chloride, sulfate, acetate, or nitrate has been found effectivein correcting a certain mineral deficiency disease in animals. Soils should contain 0.13 to 0.30 ppm of cobalt for proper animal nutrition. Cobalt is foundin Vitamin B-12, which is essential for human nutrition. Cobalt-60, an artificial isotope, is an important gamma ray source, and is extensively usedas a tracer and a radiotherapeutic agent. Single compact sources of Cobalt-60 vary from about $1 to $10/curie, depending on quantity and specificactivity. Twenty six isotopes and isomers of cobalt are known. 1
• "essential for vitamin B12, but the human body cannot make vitamin B12 from cobalt and thus requires the performed vitamin from dietary sources." 2
Physical Properties
Melting Point:3* 1495 °C = 1768.15 K = 2723 °F
Electron Configuration: [Ar] 4s2 3d7
n = 3
Electronegativity (Pauling scale):5 1.88
Specific Heat: 0.421 J/g°C 9 = 24.811 J/mol°C = 0.101 cal/g°C = 5.930 cal/mol°C
2 Al (s) + 3 CoCl2 (aq) → 2 AlCl3 (aq) + 3 Co (s)
Earth - Source Compounds: sulfides 41
External Links:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:9.
Boiling Point:3* 2927 °C = 3200.15 K = 5300.6 °F
Sublimation Point:3
Triple Point:3
Critical Point:3
Density:4 8.86 g/cm3
* - at 1 atm
Electron Configuration
Block: d
Highest Occupied Energy Level: 4
Valence Electrons:
Quantum Numbers:
ℓ = 2
mℓ = -1
ms = -½
Bonding
Electropositivity (Pauling scale): 2.12
Electron Affinity:6 0.662 eV
Oxidation States: +2,3
Work Function:7 4.70 eV = 7.5294E-19 J
Ionization Potential
eV 8
kJ/mol
1
7.881
760.4
2
17.083
1648.3
3
33.5
3232.3
4
51.3
4949.7
5
79.5
7670.6
6
102
9841.5
7
128.9
12437.0
8
157.8
15225.4
9
186.13
17958.8
Ionization Potential
eV 8
kJ/mol
10
275.4
26572.1
11
305
29428.0
12
336
32419.1
13
379
36567.9
14
411
39655.5
15
444
42839.5
16
511.96
49396.6
17
546.58
52736.9
18
1397.2
134809.3
Ionization Potential
eV 8
kJ/mol
19
1504.6
145171.8
20
1603
154666.0
21
1735
167402.0
22
1846
178111.9
23
1962
189304.2
24
2119
204452.4
25
2219
214100.9
26
9544.1
920865.4
27
10012.12
966022.5
Thermochemistry
Thermal Conductivity: 100 (W/m)/K, 27°C 10
Heat of Fusion: 16.19 kJ/mol 11 = 274.7 J/g
Heat of Vaporization: 376.5 kJ/mol 12 = 6388.6 J/g
State of Matter
Enthalpy of Formation (ΔHf°)13
Entropy (S°)13
Gibbs Free Energy (ΔGf°)13
(kcal/mol)
(kJ/mol)
(cal/K)
(J/K)
(kcal/mol)
(kJ/mol)
(s hexagonal)
0
0
7.18
30.04112
0
0
(s face centered cubic)
0.11
0.46024
7.34
30.71056
0.06
0.25104
(g)
-26.42
-110.54128
47.30
197.9032
-32.81
-137.27704
Isotopes
Nuclide
Mass 14
Half-Life 14
Nuclear Spin 14
Binding Energy
47Co
47.01149(54)#
7/2-#
347.98 MeV
48Co
48.00176(43)#
6+#
365.37 MeV
49Co
48.98972(28)#
<35 ns
7/2-#
384.62 MeV
50Co
49.98154(18)#
44(4) ms
(6+)
400.14 MeV
51Co
50.97072(16)#
60# ms [>200 ns]
7/2-#
418.46 MeV
52Co
51.96359(7)#
115(23) ms
(6+)
433.05 MeV
53Co
52.954219(19)
242(8) ms
7/2-#
449.50 MeV
54Co
53.9484596(8)
193.28(7) ms
0+
463.16 MeV
55Co
54.9419990(8)
17.53(3) h
7/2-
477.76 MeV
56Co
55.9398393(23)
77.233(27) d
4+
487.69 MeV
57Co
56.9362914(8)
271.74(6) d
7/2-
498.56 MeV
58Co
57.9357528(13)
70.86(6) d
2+
507.56 MeV
59Co
58.9331950(7)
STABLE
7/2-
517.49 MeV
60Co
59.9338171(7)
5.2713(8) a
5+
525.56 MeV
61Co
60.9324758(10)
1.650(5) h
7/2-
534.57 MeV
62Co
61.934051(21)
1.50(4) min
2+
540.78 MeV
63Co
62.933612(21)
26.9(4) s
7/2-
549.78 MeV
64Co
63.935810(21)
0.30(3) s
1+
555.99 MeV
65Co
64.936478(14)
1.20(6) s
(7/2)-
563.13 MeV
66Co
65.93976(27)
0.18(1) s
(3+)
568.40 MeV
67Co
66.94089(34)
0.425(20) s
(7/2-)#
575.54 MeV
68Co
67.94487(34)
0.199(21) s
(7-)
579.89 MeV
69Co
68.94632(36)
227(13) ms
7/2-#
586.10 MeV
70Co
69.9510(9)
119(6) ms
(6-)
589.51 MeV
71Co
70.9529(9)
97(2) ms
7/2-#
596.65 MeV
72Co
71.95781(64)#
62(3) ms
(6-,7-)
600.06 MeV
73Co
72.96024(75)#
41(4) ms
7/2-#
605.34 MeV
74Co
73.96538(86)#
50# ms [>300 ns]
0+
608.76 MeV
75Co
74.96833(86)#
40# ms [>300 ns]
7/2-#
614.03 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 14
Reactions
Al2O3 + 3 C + 3 Cl2 → 2 AlCl3 + 3 CO 15
Bi2O3 (s) + 3 C (s graphite) → 3 Bi (s) + 3 CO (g) 16
C (s graphite) + 1 H2O (g) → CO (g) + H2 (g) 17
2 C (s graphite) + 1 O2 (g) → 2 CO (g) 18
C3H8 (g propane) + 3 H2O (g) → 3 CO (g) + 7 H2 (g) 19
2 Ca3(PO4)2 (s beta) + 6 SiO2 (s quartz) + 10 C (s graphite) → P4 (g) + 6 CaSiO3 (ℓ) + 10 CO (g) 20
CaO (s) + 3 C (s) → CaC2 (s) + CO (g) 21
CH3OH (ℓ methanol) → 2 H2 (g) + CO (g) 22
CH3OH (ℓ methanol) + 1 CO (g) → CH3COOH (ℓ) 23
2 CH3SH + 1 CO → CH3COSCH3 + H2S 24
2 CH4 (g methane) + 1 O2 (g) → 2 CO (g) + 4 H2 (g) 25
CH4 (g methane) + 1 H2O (g) → CO (g) + 3 H2 (g) 25
2 CO (g) + 1 O2 (g) → 2 CO2 (g) 26
CO2 (g) + 1 C (s) → 2 CO (g) 27
Fe2O3 (s hematite) + 3 CO (g) → 2 Fe (s alpha) + 3 CO2 (g) 28
Fe2O3 (s hematite) + 3 C (s graphite) → 2 Fe (s alpha) + 3 CO (g) 29
FeO (s) + 1 CO (g) → Fe (s alpha) + CO2 (g) 30
FeO (s) + 1 C (s graphite) → Fe (s alpha) + CO (g) 30
H2O (g) + 1 CO (g) → H2 (g) + CO2 (g) 31
HCOOH (ℓ) → H2O (ℓ) + CO (g) 32
Na2SO4 (s) + 4 C (s graphite) → Na2S (s) + 4 CO (g) 33
SiO2 (s quartz) + 2 C (s graphite) → Si (ℓ) + 2 CO (g) 34
SiO2 (g) + 2 C (s graphite) + 2 Cl2 (g) → SiCl4 (g) + 2 CO (g) 35
2 TiO2 (s rutile) + 3 C (s graphite) + 4 Cl2 (g) → 2 TiCl4 (g) + CO2 (g) + 2 CO (g) 36
ZnO + 1 C → Zn + CO 37
ZnO (s) + 1 CO (g) → Zn (s) + CO2 (g) 38
2 Ca3(PO4)2 (s beta) + 6 SiO2 (s quartz) + 10 C (s graphite) → P4 (g) + 6 CaSiO3 (s wollastonite) + 10 CO (g) 39
13 C (s graphite) + 3 Cr2O3 (s) → 2 Cr3C2 (s) + 9 CO (g) 40
Abundance
Earth - Seawater: 0.00002 mg/L 42
Earth -
Crust:
25 mg/kg = 0.0025% 42
Earth -
Mantle:
0.04% 43
Earth -
Core:
0.6% 43
Earth -
Lithosphere:
0.003% 44
Earth -
Total:
840 ppm 45
Mercury -
Total:
1690 ppm 45
Venus -
Total:
820 ppm 45
Chondrites - Total: 1300 (relative to 106 atoms of Si) 46
Human Body - Total: 0.000002% 47
Compounds
cobalt(II) acetate tetrahydrate
cobalt(II) acetate; cobaltous acetate
cobalt(II) aluminate
cobalt(II) bromide; cobalt dibromide
cobalt(II) chloride hexahydrate; cobalt dichloride hexahydrate
cobalt(II) chloride; cobalt dichloride
cobalt(II) chromate
cobalt(II) chromite
cobalt(II) cyanide
cobalt(II) ferricyanide
cobalt(II) fluoride; cobalt difluoride
cobalt(II) hydroxide
cobalt(II) iodate
cobalt(II) iodide
cobalt(II) naphthenate
cobalt(II) nitrate hexahydrate; cobaltous nitrate hexahydrate
cobalt(II) nitrate; cobaltous nitrate
cobalt(II) orthosilicate
cobalt(II) oxalate
cobalt(II) oxide; cobalt monoxide
cobalt(II) perchlorate
cobalt(II) phosphate
cobalt(II) selenide
cobalt(II) stannate
cobalt(II) sulfate
cobalt(II) sulfate heptahydrate; cobaltous sulfate heptahydrate
cobalt(II) sulfide; cobaltous sulfide
cobalt(II) titanate
cobalt(II) tungstate
cobalt(III) acetylacetonate
cobalt(III) chloride; cobalt trichloride
cobalt(III) fluoride
cobalt(III) hydroxide
cobalt(III) nitrate
cobalt(III) oxide monohydrate
cobalt(III) oxide; cobalt trioxide
cobalt(III) sulfide
cobalt(III) titanate
cobalt(IV) fluoride
cobalt(IV) sulfide; cobalt disulfide
cobaltocene; bis(η5-cyclopentadienyl)-cobalt
Prices
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
Sources
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