Vapour density, also referred to as density of vapor, is a measure of the relative weight of a gas or vapour as compared to air. This parameter is commonly used in chemical and physical studies where it helps to determine the composition of various gases. Synonyms of this term include vapor mass density, molecular weight, and specific gravity. Vapour density is an essential parameter for the production of many chemicals, and it helps to determine the boiling point, melting point, and other physical properties of substances. It is important to note that the proper use of the vapour density parameter helps to ensure that products are safe for use and free from any hazardous materials.