How many milliliters of a 2.00 M NaCl stock solution are required to prepare 100.0 mL of a 0.150 M NaCl solution?

• A. 15.0 mL
• B. 75.0 mL
• C. 30.0 mL
• D. 7.5 mL

Answer: (A)

Verified step by step guidance

1. Identify the known values: the concentration of the stock solution \(C_1 = 2.00\, M\), the desired concentration of the diluted solution \(C_2 = 0.150\, M\), and the final volume of the diluted solution \(V_2 = 100.0\, mL\).
2. Recall the dilution equation which relates the concentrations and volumes before and after dilution: \[C_1 \times V_1 = C_2 \times V_2\] where \(V_1\) is the volume of the stock solution needed.
3. Rearrange the dilution equation to solve for \(V_1\): \[V_1 = \frac{C_2 \times V_2}{C_1}\]
4. Substitute the known values into the equation: \[V_1 = \frac{0.150\, M \times 100.0\, mL}{2.00\, M}\]
5. Calculate \(V_1\) to find the volume of the 2.00 M NaCl stock solution required to prepare 100.0 mL of 0.150 M NaCl solution.