Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

How much H2SO4 is required to make 225 mL of a 2% solution?

1. 2.25 g

2. 4.5 g

3. 10 g

4. 5 g

The correct answer is: 4.5 g

To determine how much H2SO4 (sulfuric acid) is required to make a 225 mL solution at a 2% concentration, you first need to understand what a 2% solution means in this context. A 2% solution by mass indicates that there are 2 grams of solute (H2SO4) in every 100 mL of solution. Let’s break down the calculation for the desired 225 mL of a 2% solution: 1. Calculate the mass of H2SO4 needed per 100 mL: - Since it's a 2% solution, this equates to 2 grams of H2SO4 in 100 mL. 2. Set up a proportion to find out how much is needed for 225 mL: - If 100 mL requires 2 grams, then 225 mL would require: \[ \text{Mass of H2SO4} = \left(\frac{2 \text{ g}}{100 \text{ mL}}\right) \times 225 \text{ mL} = 4.5 \text{ g} \] Thus, to prepare 225 m