# Homework Help: Freezing point

1. May 17, 2010

### uuuhhhx2

1. The problem statement, all variables and given/known data
A solution is made by dissolving 250.0 g of solid potassium chromate (K2CrO4) in 1.00 kg of water?
what will be the freezing point of the new solution.

2. Relevant equations
[Delta]T(freezing point)=(Van't Hoff Factor)(molal concentration of solute particles)(molal freezing point-depression constant)

Van't Hoff Factor = (moles of particles in solution/moles of solute dissolved)

molality= moles of solute/ kg of solution

3. The attempt at a solution
(250 g K2CrO4)(1 mol K2CrO4/194.188 K2CrO4) = 1.29 mol of K2CrO4
(1.29 mol K2CrO4/1.25 kg solution) = 1.0296 mol/kg
Change in freezing point = (1.0296 molality)(1.86 degrees Celsius/molality)(3 Van't Hoff Factor)
Change in freezing point = 0 degrees celsius - 5.750 degrees celsius
Change in freezing point = -5.75 degrees celsius

2. May 17, 2010

### gabriels-horn

1kg of solvent only, not 1.25kg

3. May 17, 2010

nvm i got it