Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with:
(i) iodide (ii) iron(II) solution and (iii) H₂S

In acidic medium, K₂Cr₂O₇​ behaves as a very strong oxidising agent.

   

​K₂Cr₂O₇ gains electrons to get reduced and behaves as an oxidizing agent. The reaction of K₂Cr₂O₇ with H₂S, iron (II) solution and other iodide are as follows:

(i) K₂Cr₂O₇ ​ oxidizes iodide to iodine.

(ii) K₂Cr₂O₇ oxidizes iron (II) solution to iron (III) solution i.e., ferrous ions to ferric ions.

K₂Cr₂O₇ oxidizes H₂S to sulphur.