Question

How many moles of K₂Cr₂O₇ can be reduced by 1 mole of Sn²⁺ ?

Answer 1

The balanced chemical reactions (ionic reactions)for reduction of K₂Cr₂O₇ by Sn²⁺ are:

Balanced Net reaction : 3Sn²⁺+ Cr₂O₇^2- + 14H⁺ → 3Sn⁴⁺ + 2Cr³⁺ + 7H₂O​

Thus according to the balanced reaction : 1 mole of Cr₂O₇^2- will be reduced by 3 moles of Sn²⁺ 

Thus 1 mole of Sn²⁺  will reduce = 1/3 moles of Cr₂O₇^2- 

= 0.33 moles of Cr₂O₇^2-