What is vapor often defined as?

Vapor is often defined as the gas state of a substance, particularly when that substance is in a phase that can coexist with its liquid or solid forms. This definition emphasizes the gaseous nature of vapor, which typically results from the evaporation of a liquid or sublimation of a solid at specific temperatures and pressures. In this context, vapor can exist above a liquid or solid within a closed environment, indicating a dynamic equilibrium between these states.

Understanding vapor as a gas is essential in various applications, especially in the context of hazardous materials, where the behavior of substances as vapors can significantly influence health and safety protocols. This is because vapors can disperse quickly in the air and may pose inhalation risks, which is critical knowledge for handling hazardous materials safely.