Super Saturated Fun Sheet

Question

if you use 975 grams of sucrose(C12H22O11) and dissolve this into 2500 grmans of water, what will be the change in the freezing point of your solution? The Kf of water is -1.86 degrees C/m.

Answer 1

∆T = imK

∆T = change in freezing point = ?

i = van't Hoff factor = 1 for sucrose since it's a non electrolyte

m = molality = moles sucrose / kg water = 975 g x 1 mol/342 g = 2.85 mol/2.5 kg = 1.14 m

K = freezing constant = -1.86

∆T = (1)(1.14)(-1.86) = -2.21º (answer)