Massachusetts Pharmacy Technician License Practice Test

If you dilute and repackage 1 L of a 20% solution into bottles of 5% solution, how many bottles can you fill?

1. 4

2. 6

3. 8

4. 10

The correct answer is: 8

To determine how many bottles of a 5% solution can be filled from 1 L of a 20% solution, it’s important to first understand the concept of dilution and the relationship between the concentration of the solutions. When you have a 20% solution, it means that in every 100 mL of this solution, there are 20 grams of the solute. In 1 L (or 1000 mL), you would have: \[ \text{Grams of solute} = \text{Volume} \times \text{Concentration} \] \[ = 1000 \, \text{mL} \times 0.20 = 200 \, \text{grams} \] Now, if you want to create a 5% solution, you have to determine how much total volume is needed to keep the amount of solute the same while reducing the concentration. In a 5% solution, for every 100 mL of solution, there are 5 grams of the solute. To calculate how much total volume you can get from the 200 grams of solute: \[ \text{Total volume of 5% solution} = \