Question

Give balanced equations for the following reaction:

Potassium dichromate is treated with acidified ferrous sulphate solution.

Answer 1

When potassium dichromate is treated with acidified ferrous sulphate solution, a redox reaction occurs in which:

• Ferrous ions (Fe²⁺) are oxidised to ferric ions (Fe³⁺).
• Dichromate ions \[\ce{(Cr2O^2-_7)}\] are reduced to Cr³⁺.

\[\ce{Cr2O^2-_7 + 14H+ + 6Fe^2+ -> 2Cr^3+ + 6Fe^3+ + 7H2O}\]

Balanced molecular equation with sulphuric acid:

\[\ce{K2Cr2O7 + 6FeSO4 + 7H2SO4 -> Cr2(SO4)3 + 3Fe2(SO4)3 + K2SO4 + 7H2O}\]