| Reactions of Iodine |
 Reactions with water |
| Iodine reacts with water to produce hypoiolite, OI-. The pH of the solution determines the position of the equilibrium.
|
I2(l) + H2O(l) OI-(aq) + 2H+(aq) + I-(aq) |
| Reactions with air |
| Iodine is not reactive towards with oxygen or nitrogen. However, iodine does react with ozone, O3 to form the unstable yellow I4O9.
|
| Reactions with halogens |
| Iodine reacts with fluorine at room temperature to form the iodine(V) pentafluoride. At 250°C the same reaction yields iodine(VII) heptafluoride. With
careful control of the reaction conditions, (-45°C, suspension of CFCl3), it is posible to isolate the iodine(III) fluoride.
|
I2(s) + 5F2(g) 2IF5(l) |
| I2(s) + 7F2(g)2IF7(g) |
| I2(s) + 3F2(g)2IF3(s) |
| Iodine reacts with bromine to form the very unstable interhalogen species iodine(I) bromide.
|
| I2(s) + Br2(l)2IBr(s) |
| Iodine reacts with chlorine at -80°C with excess liquid chlorine to form iodine (III) chloride.
|
| I2(s) + 3Cl2(l)I2Cl6(s) |
| Iodine reacts with chlorine in the presence of water to form iodic acid.
|
| I2(s) + 6H2O(l) + 5Cl2(g)2HIO3(s) + 10HCl(g) |
| Reactions with acids |
| Iodine reacts with hot concentrated nitric acid to form iodic acid. The iodic acid crystallizes out on cooling. |
| 3I2(s) + 10HNO3(aq)6HIO3(s) + 10NO(g) + 2H2O(l) |
| Reactions with bases |
| Iodine reacts with hot aqueous alkali to produce iodate, IO3-. Only one sixth of the total iodine is converted in this reaction.
|
| 3I2(g) + 6OH-(aq)IO3-(aq) + 5I-(aq) + 3H20(l) |
| |
| Reduction Potentials |
| Balanced half-reaction |
E0 / V
|
| I2(s) + 2e-2I- |
+0.535 |
| I2(aq) + 2e-2I- |
+0.615 |
| 3I2 + 2e-2I3- |
+0.789 |
| I3- + 2e-3I- |
+0.536 |
| H5IO6 + H+ + 2e-IO3- + 3H2O
|
+1.601 |
| HIO52- + 3H+ + 2e-IO3- + 2H2O
|
+1.898 |
| HIO52- + 8H+ + 6e-HIO + 4H2O
|
+1.389 |
| 2HIO52- + 18H+ + 14e-I2(s) + 10H2O
|
+1.384 |
| 3HIO52- + 27H+ + 22e-I3- + 15H2O
|
+1.357 |
| HIO52- + 9H+ + 8e-I- + 5H2O
|
+1.288 |
| HIO4 + 2H+ + 2e-HIO3 + H2O
|
+1.626 |
| IO4- + 2H+ + 2e-IO3- + H2O
|
+1.653 |
| HIO4 + 6H+ + 6e-HIO + 3H2O
|
+1.290 |
| IO4- + 7H+ + 6e-HIO + 3H2O
|
+1.235 |
| 2HIO4 + 14H+ + 14e-I2(s) + 8H2O
|
+1.300 |
| 3HIO4 + 21H+ + 22e-I3- + 12H2O
|
+1.276 |
| HIO4 + 7H+ + 8e-I- + 4H2O
|
+1.215 |
| IO3- + 6H+ + 4e-I+ + 3H2O
|
+1.155 |
| IO3- + 4H+ + 4e-IO- + 2H2O
|
+0.972 |
| 2IO3- + 12H+ + 10e-I2(s) + 6H2O
|
+1.196 |
| 2IO3- + 12H+ + 10e-I2(aq) + 6H2O
|
+1.178 |
| IO3- + 2Cl- + 6H+ + 4e-ICl2- + 3H2O
|
+1.24 |
| 2HIO3 + 10H+ + 10e-I2(s) + 6H2O
|
+1.169 |
| 3HIO3 + 15H+ + 16e-I3- + 9H2O
|
+1.145 |
| HIO3 + 5H+ + 6e-I- + 3H2O
|
+1.078 |
| 2HIO + 2H+ + 2e-I2(s) + 2H2O
|
+1.354 |
| 2IO- + 4H+ + 2e-I2(s) + 2H2O
|
+2.005 |
| 3HIO + 3H+ + 4e-I3- + 3H2O
|
+1.213 |
| 3IO- + 6H+ + 4e-I3- + 3H2O
|
+1.701 |
| IO- + 2H+ + 2e-I- + H2O
|
+1.313 |
| HIO + H+ + 2e-I- + H2O
|
+0.987 |
| 2ICl3(s) + 6e-I2(s) + 6Cl- |
+1.28 |
| 2ICl(s) + 2e-I2(s) + 2Cl- |
+1.22 |
| 2ICl + 2e-I2(s) + 2Cl- |
+1.19 |
| 2ICl2- + 2e-I2(s) + 4Cl- |
+1.056 |
| 2IBr(aq) + 2e-I2(s) + 2Br- |
+1.02 |