A 20.0 % (m/v) solution contains 20.0 g of solute per 100 mL of solution. Which of the following correctly expresses this concentration as a conversion factor?

• A. 20.0 g solute / 100 mL solution
• B. 100 mL solute / 20.0 g solution
• C. 100 g solute / 20.0 mL solution
• D. 20.0 mL solution / 100 g solute

Answer: (A)

Verified step by step guidance

1. Understand that a 20.0 % (m/v) solution means there are 20.0 grams of solute dissolved in every 100 mL of the total solution.
2. Identify the given concentration: 20.0 g of solute per 100 mL of solution.
3. Recognize that a conversion factor expresses the relationship between two quantities, allowing you to convert from one unit to another.
4. Write the conversion factor as the ratio of grams of solute to milliliters of solution, which is \(\frac{20.0\ \text{g solute}}{100\ \text{mL solution}}\).
5. Verify that the units in the conversion factor match the original concentration units and that the ratio correctly represents the given percentage concentration.