10 mL of 1.0 M aqueous solution of Br_(2)is added to excess of NaOH in order to disproportionate quantitatively to Br^(-) " and " BrO_(3)^(-) . The resulting soluting is made free from Br^(-)ion by extraction and excess of OH^(-) neutralized by acidifying the solution. This solution requires 1.5g of an impure CaC_(2)O_(4) sample for complete redox change . Calculate% purity of CaC_(2)O_(4) sample.

10 mL of 1.0 M aqueous solution of Br_(2)is added to excess of NaOH in

1.	10 mL of 1.0 M aqueous solution of Br_(2)is added to excess of NaOH in order to disproportionate quantitatively to Br^(-) " and " BrO_(3)^(-) . The resulting soluting is made free from Br^(-)ion by extraction and excess of OH^(-) neutralized by acidifying the solution. This solution requires 1.5g of an impure CaC_(2)O_(4) sample for complete redox change . Calculate% purity of CaC_(2)O_(4) sample.
Answer» Solution :`2Br_(2) + 6OH^(-) to 5Br^(-) + BrO_(3)^(-) + 3H_(2)O` reacts to give redox CHANGE as `Br^(5+) + 6eto Br^(-) ` (VALENCE factor = 6) `C_(2)^(3+) to 2C^(4+) + 2e^(-)` MILLIMOLE of `BrO_(3)^(-)` FORMED ` = 10/3` Meq. of `CaC_(2)O_(4) = ` Meq. of `BrO_(3)^(-) = 10/3 xx 6 = 20` `W_(CaC_(2)O_(4))/((128)/2) xx 1000 = 20 "" W_(CaC_(2)O_(4)) = 1.28 ` g ` :. " of " CaC_(2)O_(4) = (1.28)/(1.5) xx 100 = 85.33`