Question

How many electrons are required in the balanced half-reaction for the reduction of chromate ions tp chromium (iii) ions in basic solution?

Answer 1

Chromate ion : $CrO_4^{2-}$

Oxidation number of Cr : +6

Chromium(III) ion : $Cr^{3+}$

Oxidation number of Cr : +3

Number of Electrons required : 6 - 3 = 3