Question

methanol is a crystalline substance with a peppermint taste and odor.qhwn 1.50g of methanol is dissolved in 250g of cyclo hexane the freezing point of the a oliti ok n is lowered by 8.01C. calculate the molar mass methanol

Answer 1

$\Delta$Tf = 8.01 oC

Kf of cyclo hexane = 20 . 2 oC / m

$\Delta$Tf = Kf x m

8.01 = 20.2 x m

m = molality =0.3965

mass of solvent = 250 g = 0.250 kg

molality = moles of solute / mass of solvent

0.3965 = moles / 0.250

moles = 0.099

molar mass = mass / moles

= 1.50 / 0.099

= 15.15 g/mol

molar mass = 15.15 g/mol