5.2g of a limestone sample was dissolved in dil HCl and the solution was made upto 1 dm3. 25cm3 of this solution was treated with ammonium oxalate. The resulting ppt. of calcium oxalate was titrated aganist 0.111N KMnO4 in acidic medium. The end point was 22.2cm3. Calculate the percentage of calcium carbonate in the sample.
meq of CaCO3=meq of KMnO4
1000*2*w/100 = 0.111*22.2
w can be calculated then the %.