Question

A solution of $1$ moles of sucrose in $1000$ grams of water freezes at $-{0.2}^{\circ }C$. How many grams of ice would have separated at$-{0.4}^{\circ }C$:-

• A. $500grams$
• B. $300grams$
• C. $250grams$
• D. $400grams$

Answer 1

Answer: (A)

$500grams$

We know that $K_F=\frac{\Delta T_p}{m}$

$m=\frac{x\times 1000}{1000}=\frac{0.2}{K_f}⟶\left(1\right)$

at $-{0.4}^{o}C$ $m=\frac{x\times 1000}{W}=\frac{0.4}{K_f}⟶\left(2\right)$

On dividing equation $\left(1\right)$ by $\left(2\right)$;

$\Rightarrow \frac{0.2}{0.4}=\frac{W}{1000}$

$\Rightarrow W=500gm$

The amount of ice separated= $1000-500=500gm$ .