Question

What is the freezing point depression of an aqueous solution that contains 3m of ionic solute CaCl2 per 1 kg of water. The freezing point depression constant for water is -1.86 degree Celsius per mole (* CaCl2 dissociates into 3 ions)

Answer 1

Number of ions in CaCl₂ is 3 ions so, i=3, mass of water = 1 kg , molality of solution = 3m , and K_f= 1.86 ^oC / mole

for depression point constant

$\Delta T_f=iK_fm$

$\Delta T_f = 3×1.86×3=16.74 K$