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# How are percentages by volume calculated?

How do I calculate percentage by volume of a solution containing alcohol or any other liquid ?
-jefferym@ccgate.sj.nec.com

Vol/vol percentage is calculated as

 Volume % = volume of substancevolume of total solution ×100%

For example, to prepare 100 mL of 5% (v/v) solution of ethanol, pipette 5 mL of ethanol into the bottom of a 100 mL flask and dilute to the mark with water.

Careful, though. The denominator specifically says volume of total solution and NOT volume of solvent. This makes a difference, because volumes are not additive. 5 mL ethanol plus 95 mL of water does NOT equal 100 mL of solution!

Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! How are percentages by volume calculated?