Question

How many milliliters of a 0.204 M HI solution are needed to reduce 24.5 mL of a 0.371 M KMnO4 solution according to the following equation: 10HI + 2KMnO4 + 3H2SO4 → 5I2 + 2MnSO4 + K2SO4 + 8H2O

Answer 1

number of moles of KMNO4 = M* V
                                                           = 0.371 M * 0.0245 L
                                                           = 9.0895*10^-3 mol

From reaction,
2 mol of KMNO4 requires 10 mol of HI
so, number of moles of HI required = (10/2)* number of moles of KMNO4
                                                                         = 5 * 9.0895*10^-3 mol
                                                                         = 0.04545

number of moles of HI required = M*V
0.04545 = 0.204 * V
V=0.223 L
   = 223 mL
Answer: 223 mL