# Volume percent

Volume percent = 40.

Volume percent is a common expression of a solution's concentration. It is defined as:

$\textrm{volume\ percent} = \frac{\textrm{volume\ of\ solute}}{\textrm{volume\ of\ solution}}*100\%$

It is related to volume fraction by dividing by 100%.

Volume percent is usually used when the solution is made by mixing two fluids, such as liquids or gases. However, percentages are only additive for ideal gases.[1]

The solute is what you get from the solution. For example, if you distilled salt water, the solution would be the salt water, and the solvent would be the distilled water.

A solution consists of a solvent, which is commonly a liquid, and a solute, which may be any substance that dissolves in the solvent. For example, if salt water (a solution) is distilled, water (the solvent) passes over into the receiver and salt (the solute) remains in the still.

In the case of a mixture of ethanol and water, which are miscible in all proportions, the designation of solvent and solute is arbitrary. The volume of such a mixture is slightly less than the sum of the volumes of the components. Thus, by the above definition, the term "40% alcohol by volume" refers to a mixture of 40 volume units of ethanol with enough water to make a final volume of 100 units, rather than a mixture of 40 units of ethanol with 60 units of water.