Mass Percentage and Density of Solution JEE Chemistry

 

❓ Question

Concentrated nitric acid is labeled as 75% by mass. Find the volume (in mL) of the solution that contains 30 g of $HNO_3$.

Given:

• Density of nitric acid solution = 1.25 g mL⁻¹

---

✍️ Solution

Mass percentage of nitric acid:

$$\mathrm{\%}HN{O}_3=75\mathrm{\%}$$

Mass of $HNO_3$ required:

$$=30\text{ g}$$

Let the mass of the solution be $m$ g.

Using mass percentage:

$$\frac{\text{Mass of }HNO_3}{\text{Mass of solution}}\times100=75$$
$$\frac{30}{m}\times100=75$$
$$m=\frac{30\times100}{75}=40\text{ g}$$

Using the density formula:

$$\text{Density}=\frac{\text{Mass}}{\text{Volume}}$$
$$\text{Volume}=\frac{\text{Mass}}{\text{Density}}$$
$$=\frac{40}{1.25}$$
$$=32\text{ mL}$$

✅ Final Answer

$$\boxed{32\ \text{mL}}$$