# How can I calculate percent concentration by volume?

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, ${V}_{s o l u t e} = {V}_{r u b b i n g . a l c o h o l} = 150.0 m L$ and
${V}_{s o l v e n t} = {V}_{w a t e r} = 400.0 m L$

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

${V}_{s o l u t i o n} = {V}_{s o l u t e} + {V}_{s o l v e n t} = 150.0 + 400.0 = 550.0 m L$

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