Question

What will be the freezing point of a $0.5\, m\, KCl$ solution? The molal freezing point constant of water is $1.86\,{}^°C\, m^{-1}$.

• A. $- 1.86^°C$
• B. $-0.372^°C$
• C. $- 3.2^°C$
• D. $0^°C$

Answer 1

Answer: (A)

$\Delta T_{f} = iK_{f} \times m$
$= 2 \times 1.86 \times 0.5 = 1.86\,{}^{\circ}C$
$T_{f} = T^{\circ}_{f} - \Delta T_{f} = 0-1.86$
$ =- 1.86\,{}^{\circ}C$