900 mL of water is added to 100 mL of a 0.1 M solution. What is the new concentration of the solution?

• A. 0.01 M
• B. 0.009 M
• C. 0.1 M
• D. 0.09 M

Answer: (A)

Verified step by step guidance

1. Identify the initial volume and concentration of the solution. Here, the initial volume \(V_1\) is 100 mL and the initial concentration \(C_1\) is 0.1 M.
2. Determine the volume of water added, which is 900 mL. The total final volume \(V_2\) is the sum of the initial volume and the added volume: \(V_2 = V_1 + 900\) mL.
3. Use the dilution formula, which relates initial and final concentrations and volumes: \(C_1 \times V_1 = C_2 \times V_2\), where \(C_2\) is the final concentration after dilution.
4. Rearrange the dilution formula to solve for the final concentration \(C_2\): \(C_2 = \frac{C_1 \times V_1}{V_2}\).
5. Substitute the known values into the equation to find \(C_2\): plug in \(C_1 = 0.1\) M, \(V_1 = 100\) mL, and \(V_2 = 100 + 900\) mL, then calculate \(C_2\).