Question

Give balanced chemical equations for the following reaction:

Between acidified potassium dichromate and potassium iodide.

Answer 1

It oxidises potassium iodide to iodine.

\[\ce{2KMnO4 + 3H2SO4 -> K2SO4 + 2MnSO4 + 3H2O + 5O}\]

\[\ce{[2KI + H2SO4 -> K2SO4 + 2HI] \times 5}\]

\[\ce{[2HI + O -> H2O + I2] \times 5}\]

\[\ce{\overline{2\text{KMnO}_4 + 8\text{H}_2\text{SO}_4 + 10\text{KI} \leftarrow 6\text{K}_2\text{SO}_4 + 2\text{MnSO}_4 + 8\text{H}_2\text{O} + 5\text{I}_2}}\]

Or

\[\ce{2MnO^-_4 + 16H+ + 10I- -> 2Mn^{2+} + 8H2O + 5I2}\]