gaasimassi

Gaasimassi is the mass of a gas contained in a given system, typically measured in kilograms. In scientific contexts it is a fundamental quantity alongside volume, pressure, temperature, and composition, and it is especially important in thermodynamics, fluid mechanics, and chemical engineering. In a closed, non-reactive system gas mass is conserved, while chemical reactions can change the distribution of mass among products and reactants.

For an ideal gas, gas mass m can be expressed in relation to pressure P, volume V, temperature T, and the gas’s molar mass M (in kilograms per mole) by m = (P V M) / (R T), where R is the universal gas constant (approximately 8.314 J/(mol·K)). A convenient related quantity is the gas density ρ, given by ρ = P M / (R T). In mixtures, M refers to the average molar mass of the mixture, weighted by the mole fractions of its components. Thus the mass in a given volume is m = ρ V.

Measurement and estimation methods include weighing a gas-containing vessel before and after filling, or calculating mass from measured P, V, T and known composition. Real gases deviate from ideal behavior, especially at high pressures or low temperatures, and corrections are applied using equations of state with a compressibility factor Z.

Applications of gas mass appear across fields such as atmospheric science (mass of air in a volume), industrial gas processing, combustion analysis, and environmental monitoring. The term gaasimassi reflects the Estonian language usage for “gas mass.”