Question

Calculate the molality of a solution of ethanol in water in which the mole fraction of ethanol is 0.04??

Answer 1

mole fraction=0.04

So if one molof solution contain 0.04 mol of ethanol and (1-0.04)molof water=0.96

So the mass of water=0.96*18 g=17.28g

So the mass of ethanol=0.04*46 g=1.84g

total mass=18.92g

Assuming the density of solution to be 1g/ml, the vlume of the solution=18.92ml

So if18.92ml of solution contain 0.04 mol of ethanol.

So …....1ml...............................0.04/18.92mol....

so 1000ml...............................(0.04/18.92)*1000=molaritty of the solution=2.11M

Answer 2

Mole fraction=0.04. So if one mol of solution contain 0.04 mol of ethanol and (1-0.04)mol of water=0.96.

So the mass of water=0.96*18 g=17.28g. So the mass of ethanol=0.04*46 g=1.84g.

The moles of water can be obtained with mass of ethanol and mass of the solution has been carried out by solvent and water.