Which term defines the weight of a volume of pure gas compared to the weight of an equal volume of dry air at the same temperature and pressure?

The term that defines the weight of a volume of pure gas compared to the weight of an equal volume of dry air at the same temperature and pressure is called vapor density. Vapor density is important in various fields, including fire safety, as it helps to understand how gases behave in the atmosphere. Specifically, vapor density indicates whether a gas will rise or settle when released into the air, which is critical in determining how gas mixtures can influence fire behavior and the spread of smoke or toxic gases.

In contrast, terms like density ratio and specific gravity relate to broader concepts in density measurements, with specific gravity being a comparison of the density of a substance to that of a reference substance (usually water for liquids and solids). Air density refers to the density of air itself, which is not specifically focused on comparing one gas to another for fire safety applications. The correct understanding of vapor density assists in predicting how gases will behave in various situations, particularly in emergencies and fire scenarios.