Question

How much amount of NaCl should be added to 600 g of water ( Density = 1.00g/ml) to decrease the freezing point of water to “-0.2°C” ? ( The freezing point depression constant for water =2 K Kg mol^-1)

Answer 1

Solution:

$$\begin{gathered} ∆T_f=0·2°C \\ ∆T_f=i\times k_f\times m \\ NaCl\to N{a}^{+}+C{l}^{-} \\ i=2 \\ 0.2=2\times 2\times \frac{w}{58.5}\times \frac{1000}{600} \\ =\frac{1.2\times 58.5}{40}=1.76gm \end{gathered}$$