Question

Calculate the molarity of a solution of Ethanol in water in which the mole fraction of Ethanol is 0.040.

Answer 1

Moles of ethanol = 0.04 mol

Moles of water = 1 - 0.04 = 0.96 mol

Mass of water = 0.96 * 18 = 17.3g

Mass of ethanol = 0.04 * 46 = 1.84g

Mass of solution = 17.3 + 1.84 = 19.1g

Let density of solution be 1g/ml

Volume of solution = mass/density = 19.1/1 = 19.1ml = 0.0191L

Molarity = 0.04/0.0191 = 2.1M