Amount of oxalic acid present in a solution can be determined by its titration with KMnO4 solution in the presence of H2SO4. The titration gives unsatisfactory result when carried out in the presence of HCL, because HCL:
1) HCl is also oxidised along with oxalic acid byKMnO4 .
2) 2KMnO4+16HCl→2KCl+2MnCl2+5Cl2+8H2O
3) 2KMnO4+3H2SO4+5H2C2O4→K2SO4+2MnSO4+8H2O+10CO2