A sample of a mixture of CaC2O4 and MgC2O4 was dissolved in about 100 mL of aqueous acid. One half of the solution was titrated with 15.05 mL of 0.1000 M KMnO4 to the end point.
MnO4 + C2O4 = Mn + CO2 (unbalanced)
The other half of the solution was titrated with 27.40 mL of 0.1000 M EDTA to the faint pink murexide indicator end point which only titrates the calcium ions. Calculate the mass percentage of the original sample that was CaC2O4.