You have a stock solution of HNO3 with a concentration of 4.5 x 10^-4 M. However, you need 275 ml of a 2.50 x 10^-5 M solution. How much of the stock solution will you need?

15.28 mL

Explanation:

From the question given above, the following data were obtained:

Molarity of stock solution (M₁) = 4.5x10¯⁴ M

Volume of diluted solution (V₂) = 275 mL

Molarity of diluted solution (M₂) = 2.5×10¯⁵ M

Volume of stock solution (V₁) needed =.?

The volume of the stock solution needed can be obtained by using the dilution formula as illustrated below:

M₁V₁ = M₂V₂

4.5x10¯⁴ × V₁ = 2.5×10¯⁵ × 275

4.5x10¯⁴ × V₁ = 0.006875

Divide both side by 4.5x10¯⁴

V₁ = 0.006875 / 4.5x10¯⁴

V₁ = 15.28 mL

Therefore, the volume of the stock solution needed is 15.28 mL