A `2.0 g` of mixture of `Na_(2)CO_(3)` and `NaHCO_(3)` loses `0.248 g` when heated to `300^(@)C`, the temperature at which `NaHCO_(3)` decomposes to `Na_(2)CO_(3)`, `CO_(2)` and `H_(2) O`. What is the percentage of `Na_(2) CO_(3)` in mixture?

Explanation

`underset(168g)(2Na HCo_(3))to Na_(2) CO_(3)+ underset(62g)underset( ubrace(44" "18))(CO_(2)+H_(2)O`
The loss comes due to evolution of `CO_(2)` and steam 6.2 g loss occurs when the quantity of `NAHCO_(3)` is 168 g. 0.248g loss will ocuur when the quantity of `NaHCO_(3) = (168)/(62) xx 0.248 = 0.672 g`
Quanity of `Na_(2) CO_(3)` in the sample `= (2.0 - 0.672) = 1.328 g`
% of `Na_(2)CO_(3) = (1.328)/(2) xx 100 = 66.4`