1.249 g of a sample of pure and impure containing some CaO was treated with dil
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Problem
1.249 g of a sample of pure BaCO3 and impure CaCO3 containing some CaO was treated with dil. HCl and it evolved 168 mL of CO2 at NTP. From this solution BaCrO4 was precipitated, filtered and washed. The dry precipitate was dissolved in dilute H2SO4 and diluted to 100 mL. 10 mL of this solution when treated with KI solution liberated iodine which required exactly 20 mL of 0.05 *N* Na2S2O3 . Calculate percentage of CaO in the sample.