Suzanne K. answered 10/10/19
Experienced High school and community college chemistry teacher
Since the moles of Ca+2=C2O4-2= H2C2O4, the moles of Ca+2 can be found by using the balanced equation to convert moles of KMNO4 (which is equal to MnO4) to moles of H2C2O4 using coefficients in the balanced equation.
find moles of H2C2O4=(0.02378 L)(9.02 x 10-4 M)=2.14 x 10-5 mol
mole H2C2O4= 2.14 x 10-5 mol x (2 mol MnO4-/5 mol H2C2O4)=8.58 x 10-6 mol...this also equals mol of Ca+2
to find mg of calcium ion, convert mol to grams and the to mg:
8.58 x 10-6 mol Ca+2 x (40 g/mol) x (1000mg/1 g)=0.343 mg Ca+2