How can I calculate percent concentration by volume?

1 Answer
Dec 28, 2014

Percent concentration by volume is defined as the volume of the solute divided by the total volume of the solution and multiplied by 100%. This is expressed mathematically as:

#v"/"v% = (volume.solute)/(volume.solution) * 100%#

Let's take an example to show how this is done. What is the percent concentration by volume of a solution composed of 150.0 mL of rubbing alcohol and 400.0 mL of water.

So, #V_(solute) = V_(rub bi ng.alcohol) = 150.0mL# and
#V_(solvent) = V_(water) = 400.0mL#

It is of the utmost importance to know that the volume of the solution is not just the volume of the solvent, but

#V_(solution) = V_(solute) + V_(solvent) = 150.0 + 400.0 = 550.0mL#

Therefore, #v"/"v% = (150.0mL)/(550.0mL) * 100% = 27.3%#