Question

A storage battery contains a solution of $H_{2}S{O}_4$, 38% by mass. At this concentration, van't Hoff factor is 2.50. The temperature at which battery contents freeze will be:
$(K_f=1.86Kmo{l}^{-1}kg)$.

• A. $-{29.08}^{o}C$
• B. $-{25.18}^{o}C$
• C. $-{17.25}^{o}C$
• D. none of these

Answer 1

The correct option is A $-{29.08}^{o}C$

Given, $w_{H_{2}S{O}_4}=38g;W_{H_{2}O}=62g$

$\therefore \Delta T=\frac{1000\times K_f\times w}{m\times W}=\frac{1000\times 1.86\times 38}{98\times 62}$

or, $\Delta T_{Normal}=11.633$

$\because$ van't Hoff's factor $\left(i\right)=\frac{\Delta T_{exp}}{\Delta T_N}=2.50$

$\therefore \Delta T_{exp}=\Delta T_N\times 2.50=11.633\times 2.50=29.08$

$\therefore f.pt.=0-29.08=-{29.08}^{o}C$