If a solution has a concentration of 2.5% w/v, how many grams of solute are in 200 mL?

To determine how many grams of solute are in a 200 mL solution with a concentration of 2.5% w/v (weight/volume), it’s essential to understand what the concentration means. A 2.5% w/v concentration implies that there are 2.5 grams of solute in every 100 mL of solution.

To find the total grams of solute in 200 mL, you can set up a proportion based on the given concentration. Since 100 mL contains 2.5 grams, it follows that in 200 mL—the amount needed is double that, because 200 mL is twice the volume of 100 mL.

So, you calculate:

[

2.5 , \text{grams} \times 2 = 5 , \text{grams}

]

Thus, there are 5 grams of solute in 200 mL of solution at a concentration of 2.5% w/v, making this the correct answer. This approach of scaling up the quantity based on the percentage concentration is a fundamental aspect of medication math, particularly in preparing solutions and dosing.