Question

A solution of aqueous nitric acid contains 5.00% nitric acid by mass. Calculate the molarity of the solution. The molar mass of nitric acid is 61.01 g/mol.

I do not how how to approach this question

Answer 1

Let volume of solution be 1 L

volume , V = 1 L

= 1*10^3 mL

Let density of solution to be same as density of water.

density, d = 1.0 g/mL

use:

mass = density * volume

= 1 g/mL *1*10^3 mL

= 1*10^3 g

This is mass of solution

mass of solute = 5.0 % of mass of solution

= 5.0*1000.0/100

= 50.0 g

mass, m = 50.0 g

use:

number of mol,

n = mass/molar mass

=(50 g)/(61.01 g/mol)

= 0.8195 mol

volume , V = 1 L

use:

Molarity,

M = number of mol / volume in L

= 0.8195/1

= 0.8195 M

Answer: 0.820 M