Definitions for "Vapour Density"
the density of a gas relative to the density of hydrogen
The amount of mass of a vapour per unit volume of the vapour. The vapour density is expressed in grams per litre and is compared to the density of air, which is equal to 1.
The relative weight of a vapour compared to an equal volume of air (indicates whether vapours will rise or sink). If the vapour density of a substance is less than one, it will tend to rise in air; if the vapour density is greater than one, it will fall in air. Substances with high vapour densities will collect in the bottom of tanks