Which of the following correctly describes how to prepare a 10% v/v solution of ethanol?

• A. Mix 10 g of ethanol with enough water to make a final volume of 100 mL.
• B. Mix 10 mL of ethanol with 100 mL of water.
• C. Mix 10 mL of ethanol with 90 mL of water.
• D. Mix 10 mL of ethanol with enough water to make a final volume of 100 mL.

Answer: (D)

Verified step by step guidance

1. Understand that a 10% v/v (volume/volume) solution means 10 mL of ethanol is present in every 100 mL of the final solution.
2. Recognize that the percentage v/v is calculated by the formula: \(\text{\% v/v} = \frac{\text{volume of solute}}{\text{total volume of solution}} \times 100\).
3. To prepare a 10% v/v ethanol solution, you need to measure 10 mL of ethanol (the solute).
4. Add enough water (the solvent) to the 10 mL of ethanol so that the total volume of the mixture is exactly 100 mL, not just adding 100 mL of water.
5. This ensures the final solution has 10 mL ethanol in 100 mL total volume, matching the 10% v/v concentration definition.