Gases, Molar Volume, Avogadro's Law, and the Ideal Gas Law

Gases behave in a remarkably simple and predictable way compared with solids and liquids, which makes gas calculations a powerful tool in stoichiometry. The behavior of gases is summarized by the kinetic theory, which pictures gas particles as being very small compared with the distances between them, moving randomly and rapidly, and exerting negligible forces on one another except during collisions. A gas that obeys these assumptions exactly is called an ideal gas, and most real gases behave nearly ideally at ordinary temperatures and moderate pressures.

Avogadro's law states that equal volumes of gases, measured at the same temperature and pressure, contain equal numbers of molecules. A profound consequence is that the volume of a gas depends only on the number of particles, not on their