Question

Calculate the concentration of nitric acid in moles per litre in a sample which has a density $1.41g{mL}^{-1}$ and the mass per cent of nitric acid in it being $69\%$.

Answer 1

The density of the solution is 1.41 g/mL.

1000 g of the solution will have a volume $=\frac{\text{Mass}}{\text{Density}}=\frac{1000}{1.41}=709$ ml.

The mass per cent of nitric acid is $69\%$.

1000 g of the solution will have $1000\times \frac{69}{100}=690$ g of nitric acid.

The molarity of solution is $\frac{\text{Mass of nitric acid}}{\text{Molar mass of nitric acid}\times \text{Volume of solution}}=\frac{690}{63\times 709}=0.0155$ M.