In
chemistry, the
volume fraction f
i is defined as the volume of a constituent
Vi divided by the volume of all constituents of the mixture
V prior to mixing:
Being
dimensionless, its unit is 1; it is expressed as a number, e.g., 0.18. It is the same concept as
volume percent (vol%) except that the latter is expressed with a
denominator of 100, e.g., 18%.