1.4 g of a sample of chalk `(CaCO_(3))` containing clay as impurity were treated with excess of dilute hydrochloric acid. Volume of `CO_(2)` evolved when measured at `15^(@)C` and 768 mm pressure was `282cm^(3)`. Calculate the percentage purity of the sample.

Answer

`86.1%`

Explanation

`underset(100g)(CaCO_(3))+2HCl rarrCaCl_(2)+H_(2)O+underset(22400cm^(3)"at S.T.P.")(CO_(2))`
First convert the given volume to volume at S.T.P.
Calculate the mass of `CaCO_(3)` from which this volume of `CO_(2)` at S.T.P. is obtained. Then calculate `%` age purity.