Reactions with water
2CoO(s)Reactions with air2Co3O4(s)2CoO(s)Reactions with halogensCoCl2(s)CoBr2(s)CoI2(s)Reactions with acidsCo2+(aq) + SO42-(aq) + H2(g)|
Compounds | Reactions | Production
|
| Reactions of Cobalt |
| Reactions with water |
| Water has little or no effect on cobalt. However, the reaction of red-hot cobalt and steam produces cobalt(II) oxide. |
| 2Co(s) + O2(g)2CoO(s) |
| Reactions with air |
| Cobalt is not very reactive with air. Cobalt will not react directly with nitrogen. Heating will produce cobalt oxide. |
| 3Co(s) + 4O2(g)2Co3O4(s) |
| Heating above 900°C will result in cobalt(II) oxide being formed. |
| 2Co(s) + O2(g)2CoO(s) |
| Reactions with halogens |
| Cobalt reacts with chlorine, bromine and iodine to form cobalt dihalides. |
| Co(s) + Cl2(g)CoCl2(s) |
| Co(s) + Br2(l)CoBr2(s) |
| Co(s) + I2(s)CoI2(s) |
| Reactions with acids |
| Cobalt metal dissolves in dilute sulphuric acid to form solutions containing the Co(II) ion and hydrogen gas. |
| Co(s) + H2SO4(aq)Co2+(aq) + SO42-(aq) + H2(g) |
| Reduction Potentials | |
| Balanced half-reaction | E0 / V |
Co3+ + e- Co2+ |
+1.808 |
| Co2+ + 2e-Co(s) |
-0.277 |
| Co3O4(s) + 8H+ + 2e-3Co2+ + 4H2O
|
+2.11 |
| Co2O3(s) + 6H+ + 2e- 2Co2+ + 3H2O
|
+1.75 |
| Co(OH)2(s) + 2e-Co(s) + 2OH- |
-0.73 |
| Co(NH3)63+ + e-Co(NH3)62+ |
+0.1 |
| CoO(OH)(s) + H2O + e-Co(OH)2(s) + OH- |
+0.17 |