At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.
At constant pressure, the volume of a fixed mass of gas is directly proportional to its temperature measured on the Kelvin scale.
Combined (General) Gas Law
Standard temperature and pressure (s.t.p.)
100,000 Pa and 273 K
Gay-Lussac's Law of Combining Volumes
In a reaction between gases, the volumes of the reacting gases and the volumes of any gaseous products are in the ratio of small whole numbers, provided that the volumes are measured at the same temperature and pressure.
Equal volumes of gases contain equal numbers of molecules, under the same conditions of temperature and pressure.
A gas that obeys all of the assumptions of the kinetic theory of gases under all conditions of temperature and pressure.
Equation of State for an Ideal Gas
pV = nRT
A liquid that vaporises easily.