When the solute is a liquid sometimes it is convenient to express its concentration in volume/volume percent (v/v %). The definition of v/v % is
Wine has about 12 mL of alcohol (ethanol) per 100 mL of solution. Wine wouuld have the following v/v % alcohol content:
Alcoholic beverages often have alcohol content cited as "proof". The proof value is twice the v/v % value. Therefore the above wine wouuld be 24 % proof.