Question

Calculate the concentration of nitric acid in mole per litre in a sample that has a density $1.41g/mL$ and the mass percentage is 69%.

Answer 1

Step 1: Calculating the volume of the solution

Density: The density of a solution is defined as the ratio of mass to volume. It is represented by $\rho$.

$\text{Density}=\frac{\text{Mass(g)}}{\text{Volume}\left(mL\right)}$

Let us consider the mass of solution $=100g$

Mass percentage of $HN{O}_3=69$%

Now mass of $HN{O}_3=69g$

$\text{Volume;of;solution}=\frac{\text{Mass}}{\text{Density}}$

$\text{Volume;of;solution}=\frac{100g}{1.41g/mL}$

$\text{Volume;of;solution}=70.92mL$

Step 2: Calculating the concentration of nitric acid in moles per litre

Molarity is defined as the concentration of a solute in the moles per litre of a solution.

Molecular weight of $HN{O}_3=1+14+48=63g$

Given weight of $HN{O}_3=69g$

Volume of solution $=70.92mL$

$\text{Molarity}=\frac{\text{Given;mass}\times 1000}{\text{Molar;mass}\times \text{Volume(mL)}}$

$\text{Molarity}=\frac{69\times 1000}{63\times 70.92}$

$\text{Molarity}=15.44mol{L}^{-1}$