If a concentrated solution of acetic acid is 99.5 % HC2 H3 O2 and has a density of 1.05 g/mL, what is the concentration of this acid in moles per litre?

[CH₃COOH] = 17.4 M

Explanation:

Acetic acid → CH₃COOH

Molar mass → 60 g/mol

99.5% is percent by mass concentration. It means that 99.5 grams of solute are contained in 100g of solution.

Density → 1.05 g/mL. This data is always referred to solution, not solute!.

We determine solution's volume:

1.05 g/mL = 100 g / V → V = 100 g /1.05 g/mL → 95.2 mL

Now we know, that 99.5 g of acetic acid are contained in 95.2 mL

Let's convert to mmoles → 99.5 g / 60 g/mol = 1.66 moles

We convert solution's volume to L → 95.2 mL . 1L / 1000 mL = 0.0952 L

M (mol/L) = 1.66 mol / 0.0952 L = 17.4 M