Question

Determine the freezing point depression of 2 kg of water when 2 mol salt is added to it. The kf of water is 1.86 degrees C/M. Show all your work.

Answer 1

Answer: The freezing point depression is $1.86^0C$

Explanation:

Depression in freezing point is given by:

$\Delta T_f=K_f\times m$

$\Delta T_f$ = Depression in freezing point

$K_f$ = freezing point constant = $1.86^0C/m$

m= molality = $\frac{\text {moles of solute}}{\text {mass of solvent in kg}}=\frac{2mol}{2kg}=1m$

$\Delta T_f=1.86mol/kg^0C\times 1m$  

$\Delta T_f=1.86^0C$  

Thus freezing point depression is $1.86^0C$