Question

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

• 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) $=-3.72^{\text{o}}\text{C}$