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Introduction

This chapter introduces the equation that relates the pressure, volume, absolute temperature and number of moles of an ideal gas: the equation of state of an ideal gas.

By applying ideas of mechanics to the motion of molecules, we can derive a formula that relates the pressure of a gas to its density and root mean square speed of the molecules. Combining this equation with the equation of state results in one of the jewels of nineteenth-century physicsâ€”that the average kinetic energy of molecules is directly proportional to the absolute temperature.