A mixture of  $N{a}_{2}C{O}_3$ and  $NaHC{O}_3$ weighing 10 gm is heated, 0.224 L of $C{O}_2$ is evolved at STP. Calculate the wt % of  $N{a}_{2}C{O}_3$ in mixture.

$N{a}_{2}C{O}_3$ is thermally stable in comparison to  $NaHC{O}_3$ Therefore the  $C{O}_{2\left(g\right)}$ is coming only from $NaHC{O}_3$ not from  $N{a}_{2}C{O}_3$ Let wt. of  $NaHC{O}_3$  is ‘x’ g and $N{a}_{2}C{O}_3$  is ‘y’ g 

$\therefore x+y=10g$
 
 $2NaHC{O}_{3\left(s\right)}\to N{a}_{2}C{O}_{3\left(s\right)}+C{O}_{2\left(g\right)}+H_2{O}_{\left(g\right)}$

$2\times 84g=22.4L$
 $\therefore x=0.224L$
 
 $x=1.68g$
Wt of  $N{a}_{2}C{O}_3=10-1.68=8.32g$
 $\therefore wt\%ofN{a}_{2}C{O}_3$  in mixture

$=\frac{8.32}{10}\times 100$

= 83.2%