0.1 g of a solution containing $\mathrm{Na}_2 \mathrm{CO}_3$ and $\mathrm{NaHCO}_3$ requires 10 mL o

Question

0.1 g of a solution containing $\mathrm{Na}_2 \mathrm{CO}_3$ and $\mathrm{NaHCO}_3$ requires 10 mL of 0.01 N HCl for neutralization using phenolphthalein as an indicator. Mass $\%$ of $\mathrm{Na}_2 \mathrm{CO}_3$ in solution is:

Professor PC Thomas Classes · Answer

(d) In presence of phenolphthalein $$ \begin{aligned} & \underset{50 \%}{\left(\mathrm{Na}_2 \mathrm{CO}_3ight.}+\underset{	ext { No reaction }}{\left.\mathrm{NaHCO}_3ight)} \ & \frac{1}{2} 	ext { eq. of } \mathrm{Na}_2 \mathrm{CO}_3=	ext { eq. of } \mathrm{HCl} \ & \qquad \frac{1}{2} 	imes \frac{x}{106} 	imes 2=\frac{10 	imes 0.01}{1000} \ & \quad x=0.0106 \ & \% 	ext { of } \mathrm{Na}_2 \mathrm{CO}_3=\frac{0.0106}{0.1} 	imes 100=10.6 \end{aligned} $$