This number is usually written 6.02 X 10 to the power of 23 and is called the Avogadro constant. This number of particles of any substance is called one mole of the substance. See Mole . The universal gas law combines Boyle's law, Charles's law, and Avogadro's law into a single statement. In this equation, P represents the pressure of the gas, V represents its volume, n represents the number of moles of gas, and T represents its absolute temperature.
R is a constant called the universal gas constant.
It has a value of 8.314 joules per kelvin per mole. During the early 1600's, scientists began realizing that some matter can exist in a form that is similar to air. The word gas was first used to describe this form in the mid-1600's in the writings of the Belgian chemist and physician Jan Baptista van Helmont. He invented the word gas by altering the Greek word chaos, meaning space. In this way, the word describes the ability of a gas to fill any amount of space.