Massachusetts Pharmacy Technician License Practice Test

To prepare 800 mL of a 1.5% drug solution, how many ampules of 80% solution are needed if each ampule contains 15 mL?

1. Two ampules

2. One ampule

3. Three ampules

4. Four ampules

The correct answer is: One ampule

To determine how many ampules of an 80% solution are needed to prepare 800 mL of a 1.5% drug solution, it is important first to understand the relationship between concentration and volume. A 1.5% solution means that there are 1.5 grams of the drug per 100 mL of solution. Therefore, in 800 mL of a 1.5% solution, you would have: 1.5 grams/100 mL * 800 mL = 12 grams of the drug. Now, since you are starting with an 80% solution, it contains 80 grams of the drug in every 100 mL. To find out how much volume is necessary to obtain 12 grams, you can set up a proportion using the concentration of the 80% solution: 80 grams/100 mL = 12 grams/X mL. Cross-multiplying gives: 80X = 1200, X = 1200/80, X = 15 mL. This means that to obtain 12 grams of the drug, you need a total volume of 15 mL of the 80% solution. Given that each ampule contains 15