Question

The correct set-up for solving the following problem would be:

A concentrated solution of HCI is 11.7 M and has a density of 1.65 g/mL. What is the % by mass of HCI in this solution?
16

Answer 1

M HCl = 11.7 M = 11.7 mol/L = 0.0117 mol/ml

mass HCl = 36.5 g/mol x 0.0117 mol/ml =0.427 g/ml

% mass = mass HCl : density

% mass = 0.427 : 1.65 = 0.259 = 25.9%

or formula:

M = (%mass x ρ x 10) : MM

% mass = (M x MM) : (ρ x 10)

% mass = (11.7 x 36.5) : (1.65 x 10)

% mass = 25.9