Vapor

A vapor is the gaseous form of a substance that is normally liquid or solid under the surrounding conditions. It can form by evaporation or sublimation and can condense back into a liquid or deposit as a solid.

Vapor pressure: The pressure exerted by a vapor in equilibrium with its condensed phase at a given temperature. It quantifies the tendency of this substance to enter the vapor phase.
Phase (matter): A physically distinct form of matter with uniform composition and properties. Vapor is one phase among the possible states of a substance.
Distillation: A separation method that vaporizes a liquid mixture and condenses its components selectively. Differences in volatility let distillation separate substances through their vapor phases.
Aerosol: A suspension of fine solid particles or liquid droplets in a gas. A visible mist may contain droplets rather than the substance's vapor.
Evaporation: The transition from liquid to gas at a surface, occurring below the boiling point. It produces vapor as faster-moving surface molecules escape the liquid.
Gas: A state of matter that expands to fill its container and is readily compressible. Unlike vapor, gas commonly names substances gaseous under the surrounding conditions.
Vapor-compression refrigeration: A refrigeration cycle that compresses, condenses, expands, and evaporates a working fluid. The cycle moves heat by repeatedly changing a refrigerant between vapor and liquid.
Steam: Water in its gaseous phase, often used especially for hot water vapor. Steam is the familiar substance-specific case of vapor.
Boiling: The rapid vaporization of a liquid when bubbles form throughout it at its boiling point. It creates vapor throughout a liquid rather than only at its surface.
Phase diagram: A graph showing which phases of a substance are stable at different temperatures and pressures. It locates the conditions under which a substance can exist as vapor.

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CondenserNarrower topic: The condenser's incoming stream is vapor that can liquefy under suitable conditions.