A `2.0 g` sample of a mixture containing sodium carbonate, sodium bicarbonate and sodium sulphate is gently heated till the evolution of `CO_(2)` ceases. The volume of `CO_(2)` at `750mm Hg` pressure and at `298 K` is measured to be `123.9 mL`. A `1.5 g` of the same sample requires `150 mL` of `(M//10) HCl` for complete neutralisation. Calculate the percentage composition of the components of the mixture.

Options

A. `10%`
B. `71%`
C. `31.5%`
D. `50%`

Answer

C

Explanation

`2NaHCO_(3) rarr Na_(2)CO_(3)+H_(2)O+CO_(2)`
No. of moles of `NaHCO_(3)` in the mixture `=(112)/(22400) xx 2 = 0.01`
No. of equivalents of `NaHCO_(3) = 0.01`
No. of eqts of `(NaHCO_(3)+Na_(2)CO_(3)) =` No. of eqts of HCI reacted `= 0.2 xx 0.1 = 0.01`
weight of `(Na_(2)CO_(3) +NaHCO_(3)) = (0.01 xx 53) +(0.01 xx 84) = 1.37gm`
% of `Na_(2)SO_(4) = ((2-1.37)/(2)) xx 100 = 31.5%`