Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).

Given:

Mole Fraction of Ethanol = 0.040

Density of water = 1g/ml

Mass of 1000ml of water = 1000×1

= 1000 g

Let the number of moles of ethanol be X

Number of moles of water = 1000/18

= 55.556 moles

Mole Fraction of component

0.040

0.04X 2.22224 = X

X – 0.04X = 2.22224

0.96X = 2.22224

X = 2.3148 moles

Molarity, M_o

= 2.315 mol/L

Therefore, the molarity of the solution is 2.315 mol/L.