Question

1.   Calculate the freezing point of a solution containing 50.0 g of NaCl in 5000 mL of water. K_f for water is 1.86 C˚/m  

Answer 1

Molar mass of NaCl$=58.44g/mol$

$\Delta\>T_f=k_f×m×i$

Concentration of NaCl$=\frac{50}{5}=10g/kg$

$=\frac{10}{58.44}=0.1711$

$\Delta\>T_f=1.86×0.1711×2$

$=0.6366°C$

Freezing point $=0-0.6366$

$=-0.6366°C$