2 KMnO4 + 5 Sn2+ + 16 H+ → 5 Sn4+ + 2 Mn2+ + 8 H2O + 2 K+
(0.1 mol Sn2+) x (2 mol KMnO4 / 5 mol Sn2+) = 0.04 mol KMnO4
K2Cr2O7 + 3 Sn2+ + 14 H+ → 3 Sn4+ + 2 Cr3+ + 7 H2O + 2 K+
(0.1 mol Sn2+) x (1 mol K2Cr2O7 / 3 mol Sn2+) = 0.03333 mol K2Cr2O7
(0.04 mol KMnO4) / (0.03333 mol K2Cr2O7) = 0.12 / 0.1 = 1.2 =