What will be the concentration of 150. mL of a 2.4 M NaOH solution if it is diluted to form 200. mL of solution?

What will be the concentration of 150. mL of a 2.4 M NaOH solution if it is diluted to form 200. mL of solution?

• A. 2.0 M
• B. 1.8 M
• C. 3.2 M
• D. 1.6 M

Answer: (B)

When you dilute a solution, the number of moles of solute stays the same while the volume increases, so the concentration drops in proportion to the change in volume. Use M1V1 = M2V2. Here, M1 = 2.4 M and V1 = 150 mL, V2 = 200 mL, so M2 = M1 × V1 / V2 = 2.4 × 150/200 = 2.4 × 0.75 = 1.8 M. In other words, increasing the volume by a factor of 200/150 (4/3) reduces concentration to 3/4 of the original. The diluted solution has a concentration of 1.8 M.

When you dilute a solution, the number of moles of solute stays the same while the volume increases, so the concentration drops in proportion to the change in volume. Use M1V1 = M2V2. Here, M1 = 2.4 M and V1 = 150 mL, V2 = 200 mL, so M2 = M1 × V1 / V2 = 2.4 × 150/200 = 2.4 × 0.75 = 1.8 M. In other words, increasing the volume by a factor of 200/150 (4/3) reduces concentration to 3/4 of the original. The diluted solution has a concentration of 1.8 M.