Gassvolum

Gassvolum refers to the three-dimensional space that a quantity of gas can occupy under specified temperature and pressure. In practice, the volume of a gas is not fixed; for a given amount of substance, the volume increases when the temperature rises and decreases when the pressure increases, in accordance with the general gas law PV = nRT.

Units and conventions: Commonly used units include cubic meters (m^3) and liters (L). In industry and science, volumes are often expressed at standard conditions, yielding normal cubic meters (Nm^3) or standard liters (Sm^3), where the gas volume is normalized to defined standard temperature and pressure. Regional definitions vary, with some standards using 0 °C and 1 atm, others using 20 °C and 1 atm or other reference states.

Physical basis: For ideal gases, V = nRT/P; for real gases, deviations are described by a compressibility factor Z. At high pressures or low temperatures, Z differs from 1 and corrections are applied to estimate true gas volume.

Applications: Gas volume is essential in chemical engineering, process design, gas distribution, energy accounting, and safety risk analyses. It is used when converting between moles, mass, and measurable volume, and when calculating fuel use or emissions.

See also: Ideal gas law, Molar volume, STP, Standard conditions, Compressibility factor.