$10.0 \mathrm{ml}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ solution is titrated against $0.2$ $\mathrm{M} \mathrm{HCl}$ solution. The following titre values were obtained in 5 readings.
$4.8 \mathrm{ml}, 4.9 \mathrm{ml}, 5.0 \mathrm{ml}, 5.0 \mathrm{ml}$ and $5.0 \mathrm{ml}$
Based on these readings, and convention of titrimetric estimation of concentration of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ solution is_______ $\mathrm{mM}$.
(Round off to the Nearest integer)
Most precise volume of $\mathrm{HCl}=5 \mathrm{ml}$ at equivalence point
Meq. of $\mathrm{Na}_{2} \mathrm{CO}_{3}=$ meq. of $\mathrm{HCl}$.
Let molarity of $\mathrm{Na} 2 \mathrm{CO}_{3}$
solution $=\mathrm{M}$, then
$\mathrm{M} \times 10 \times 2=0.2 \times 5 \times 1$
$\mathrm{M}=0.05 \mathrm{~mol} / \mathrm{L}$
$=0.05 \times 1000$
$=50 \mathrm{mM}$