Reaction,
2MnO4- + 5C2O4^2- + 16H+ ---> 2Mn2+ + 10CO2 + 8H2O
moles of KMnO4 used = 0.006363 M x 18.04 ml
                                    =
0.1148 mmol
moles of C2O4^2- reacted = 0.1148 x 5/2
                                           =
0.287 mmol
moles of La3+ present = 0.287 x 2/3
                                   Â
= 0.1913 mmol
molarity of La3+ in the unknown = 0.1913/49.96
                                                  Â
= 0.00383 M
