Question

Calculate the freezing point
lowering of a 5% solution of glucose
(M.mass=180) inwater.(kf for wateris 1.86 K/molal)

Answer 1

We need to find DeltaTf

Given,

5% Glucose means,

5g of Glucose (C6H12O6) in 95g of water (H2O)

so, w1 = 95g, w2 = 5g

Molecular weight of Glucose (M2) = 180g/mol

Kf = 1.86

DeltaTf = (w2*kf*1000)/(w1*M2)

DeltaTf = (5*1.86*1000)/(95*180)

DeltaTf = 9300/17100

DeltaTf = 0.5438 °K