Question

How many milliliters of water must be added to 50.0 mL of 10.0 M HNO3 to prepare 4.00 M HNO3?

• A. 50.0 mL
• B. 125 mL
• C. 250 mL
• D. 75.0 mL

Hint:

Use the dilution formula to calculate the final volume after dilution and subtract the initial volume to find the amount of solvent added.

Answer 1

The Correct Option is D

We can use the dilution formula \( M_1 V_1 = M_2 V_2 \), where \( M_1 = 10.0 \, M \), \( V_1 = 50.0 \, {mL} \), \( M_2 = 4.00 \, M \), and \( V_2 \) is the final volume. Solving for \( V_2 \): \[ (10.0 \, {M}) (50.0 \, {mL}) = (4.00 \, {M}) V_2 \] \[ V_2 = \frac{(10.0 \times 50.0)}{4.00} = 125 \, {mL} \] So, the volume of water to be added is: \[ V_{{water}} = 125 \, {mL} - 50.0 \, {mL} = 75.0 \, {mL} \] Thus, the correct answer is (d).