Question

The freezing point of 1 molal NaCl solution assuming NaCl to be 100% dissociated in water is - $\left(\mathrm{K}_{\mathrm{f}}\right.$ for $\left.\mathrm{H}_2 \mathrm{O}=1.86^0 \mathrm{C} \mathrm{m}^{-1}\right)$

• A. $-1.86^{0}C$
• B. $-3.72^{0}C$
• C. $+1.86^{0}C$
• D. $+3.72^{0}C$

Answer 1

Answer: (B)

The freezing point of 1 molal NaCl solution assumtextng NaCl to be 100% dissociated in water is -

$\Delta \text{T}_{\text{f}}=\text{i}\times \text{K}_{\text{f}}\times \text{m}$

$=2\times 1.86\times 1=3.72^{\text{o}}\text{C}$

Freezing point = (0-3.72) $= \, -3.72^{\text{o}}\text{C}$