6. Solution to Chemistry Problem

2. A solution of 200.0 ml was prepared from a 0.6524 g sample of double carbonate nBaCO3*mCaCO3. Barium was isolated from 20.0 ml of this solution as BaSO4. An excess of Na4EDTA solution (25.00 ml of 0.1 M (K = 0.9616)) was used to dissolve this precipitate in the filtrate. The filtrate and washings were collected in a 100.0 ml measuring flask and brought to the mark with distilled water. An aliquot of 10.00 ml of the resulting solution was titrated thermometrically with 0.1 M MgSO4 (K = 0.9721). The deviations of the device measuring the heat effect of the reaction were:

V(MgSO4), ml 0.2 0.4 0.6 0.8 1.0 1.2
A, scale divisions 13 26 38 42 42 42
Determine the mass fraction (%) of BaCO3 in the double carbonate under study.