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Homework Statement
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.
Homework 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
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
though the answer keys tells me its -7.18? please help me out