Vaporphase

Vapor phase refers to the state of matter in which a substance exists as a gas. It is typically used for substances that are liquids or solids at room temperature but can form a gaseous phase through evaporation or sublimation. The term vapor phase emphasizes the gaseous form of a substance derived from a condensed phase, as opposed to a substance that is inherently gaseous under standard conditions.

In thermodynamic terms, a liquid or solid in contact with its vapor has a vapor pressure, the equilibrium pressure exerted by the vapor at a given temperature. Vapor concentration in a system depends on temperature, pressure, and the volatility of the substance. A vapor can condense back to liquid or solid if it is cooled or compressed, and it can persist as a mixture of vapors with other gases in air.

Vapor-phase processes are central to many technologies. Chemical vapor deposition uses volatile precursors that decompose or react on a substrate to form solid films, while physical vapor deposition relies on vaporization of material followed by condensation. Gas-phase reactions occur in the absence of condensed phases and underpin combustion, atmospheric chemistry, and various industrial syntheses. The study of vapor-phase chemistry involves kinetics, thermodynamics, and transport phenomena.

Characterization of vapors employs spectroscopic methods, mass spectrometry, and other analytical techniques to determine composition and partial pressures. Vapor-phase behavior is influenced by volatility, vapor pressure, and interactions with surrounding media. Vapors can pose hazards such as flammability, toxicity, or corrosivity, necessitating proper handling, ventilation, and safety protocols.