Question

What happens when H₂S is passed in an acidified solution of K₂Cr₂O₇?

Answer 1

When potassium dichromate (K₂Cr₂O₇) is treated with acidified ferrous sulphate (FeSO₄), a redox reaction takes place.

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