Question

Number of moles of k2cr2o7 reduced by one mole of sn2+ ions is

Answer 1

number of moles of K2 cr2 O7 reduced by 1 mole of SN 2 + ion is 1/3

Answer 2

The balanced chemical reactions (ionic reactions)for reduction of K2Cr2O7 by Sn2+ are:
Cr2O72- + 14H++ 6e-→2Cr3+ + 7H2O
( ​Sn2+ → Sn4+ + 2e- )    × 3
 

Balanced Net reaction : 3Sn2++ Cr2O72- + 14H+ → 3 Sn4+ + 2Cr3+ + 7H2O​

Thus according to the balanced reaction : 1 mole of Cr2O72- will be reduced by 3 moles of Sn2+
Thus 1 mole of Sn2+  will reduce = 13 moles of Cr2O72-
                                                            = 0.33 moles of Cr2O72-