Question

Commercially available hydrobromic acid solution contain 48% HBr by mass. Find the molarity of the solution.The density is 1.5.

Answer 1

ANSWER

Let the volume of HBr solution be 1 L or 1000 mL.

The density of HBr solution is 1.50 g/mL.

Hence, the mass of 1000 mL of the solution is 1.50 g/mL ×1000 mL = 1500 g.

The concentration of HBr is 48% by mass.

Hence, the amount of HBr present in 1500 g of solution is

$\frac{1500 \times 48}{100} = 720g$

The molar mass of HBr is 80.9 g/mol.

Hence, the number of moles of HBr present is

$\frac{720}{80.9} = 8.9mol$

Thus, the molarity of HBr is 8.9 M.