Calculate the amount of (molar mass = ) which must be added to of water to lower its freezing point…

Calculate the amount of $\text{CaCl}_2$ (molar mass = $111\text{ g mol}^{-1}$) which must be added to $500\text{ g}$ of water to lower its freezing point by $2\text{ K}$, assuming $\text{CaCl}_2$ is completely dissociated. ($K_f\text{ for water} = 1\cdot86\text{ K kg mol}^{-1}$).