Chemistry Practice Problems Freezing Point Depression Practice Problems Solution: A 5 g sample of CaI2 is completely dissolved in 22...

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Solution: A 5 g sample of CaI2 is completely dissolved in 22 g of water, what is the freezing point of the solution? Assume complete dissociation of the salt. Kf for water is 1.86°C/m.

Problem

A 5 g sample of CaI2 is completely dissolved in 22 g of water, what is the freezing point of the solution? Assume complete dissociation of the salt. Kf for water is 1.86°C/m.

Solution

We’re being asked to find the freezing point of a solution when CaI2 is dissolved in water. When calculating the freezing point of a solution, we’re going to use the equation for Freezing Point Depression.


∆Tf = change in freezing point = Tf pure solvent –Tf solution
Kf = freezing point depression constant
i = van' t Hoff factor of the solute = no. of ions
m = molality


Let’s first calculate the molality of the solution.

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