Applications
Iodometry in its many variations is extremely useful in volumetric analysis. Examples include the determination of copper(II), chlorate, Hydrogen peroxide, and dissolved oxygen:
- 2 Cu2+ + 4 I- → 2 CuI + I2
- 6 H+ + ClO3- + 6 I- → 3 I2 + Cl- + 3 H2O
- 2 H+ + H2O2 + 2 I- → I2 + 2 H2O
- 2 H2O + 4 Mn(OH)2 + O2 → 4 Mn(OH)3
- 2 Mn3+ + 2 I- → I2 + 2 Mn2+
Available chlorine refers to chlorine liberated by the action of dilute acids on hypochlorite. Iodometry is commonly employed to determine the active amount of hypochlorite in bleach responsible for the bleaching action. In this method, excess but known amount of iodide is added to known volume of sample, in which only the active (electrophilic) can oxidize iodide to iodine. The iodine content and thus the active chlorine content can be determined with iodometry.
The determination of arsenic(V) is the reverse of the standardization of iodine solution with sodium arsenite, where a known and excess amount of iodide is added to the sample:
- As2O5 + 4 H+ + 4 I- ⇌ As2O3 + 2 I2 + 2 H2O
For analysis of antimony(V), some tartaric acid is added to solubilize the antimony(III) product.
Read more about this topic: Iodometry