Percent solutions are commonly expressed in three forms: weight/volume percentage, volume/volume percentage, and weight/weight percentage. In each scenario, the percent concentration is calculated by comparing the volume or weight of the solute to the total volume or weight of the solution.It's worth mentioning that the volume percent (v/v%) is not only used when the solute is a liquid, but it's also applicable when the numerator is in weight units and the denominator in volume units, resulting in a weight/volume percent.
The Formula for Volume Percent
Volume percent = (Volume of solute / Volume of solution) x 100
Example 1
What would be the volume/volume percent solution if we combine 30 mL of ethanol with enough water to make 250 mL of solution?
Solution
The given parameters are:
Volume of solute is 30 mL
Volume of solution is 250 mL
We substitute the values in the formula:
Volume percent = (Volume of solute / Volume of solution) x 100%
= (30 mL / 250 mL) x 100%
Therefore, the volume percent is 12%
Example 2
If we dissolve 70 mL of hydrogen peroxide in enough water to produce 2000 mL of solution, what would be the concentration of the hydrogen peroxide solution?
Solution
The given parameters are:
Volume of solute is 70 mL
Volume of solution is 2000 mL
We substitute the values in the formula:
Volume percent = (Volume of solute / Volume of solution) x 100%
= (70 mL/ 2000mL) x 100%
Therefore, the volume percent is 3.5%
