Answer to Question #302402 in General Chemistry for Lea

Question

calculate the molarity and the molality of an NH3 solution made up of 30g of NH3 in 70g water. The density of solution is .982g/ml.

Answer 1

No. Of moles of NH₃ = 30/17 = 1.764 moles

Mass of water = 70 g

Mass of solution = 100g

Volume of solution = 100×0.982 = 98.2 ml

Volume of solvent = 70ml

Molarity = (1.764/98.2)×1000 = 17.96

Molality = (1.764/70)×1000 = 25.2

Mass % NH₃ = (30/100)×100 = 30%

Mass % of water = (70/100)×100 = 70%