Calculate the molality of a 35.0% (by mass)aqueous solution of nitric acid.
A)6.64
B)538
C)2.19
D)3.32
E)The density of the solution is needed to solve the problem.

Question

Quizplus · Accepted Answer

The correct answer is A because the molality of a solution is defined as the number of moles of solute per kilogram of solvent. In this case, the solvent is water and the solute is nitric acid. The mass of the solution is 100 g, and the mass of the nitric acid is 35 g. The molar mass of nitric acid is 63 g/mol, so the number of moles of nitric acid is 35 g / 63 g/mol = 0.556 mol. The mass of the water is 100 g - 35 g = 65 g. The molality of the solution is therefore 0.556 mol / 0.065 kg = 6.64 mol/kg.

Calculate the Molality of a 35