gas

Methods of gas collection in the laboratory. The methods reflect the different properties of the various gases, for example collection over water is only suitable for gases that is not soluble in water. The syringe is suitable for collecting all gases.

Form of matter, such as air, in which the molecules move randomly in otherwise empty space, filling any size or shape of container into which the gas is put.

A sugar-lump sized cube of air at room temperature contains 30 trillion molecules moving at an average speed of 500 metres per second (1,800 kph/1,200 mph). Gases can be liquefied by cooling, which lowers the speed of the molecules and enables attractive forces between them to bind them together.

Gas is one of the three states of matter (solid, liquid, gas). The way that solids, liquids, and gases behave can be explained by the kinetic theory of matter and particle theory.