Equation of State
Suppose the gas is in the initial state with volume V1, pressure P1, and temperature T1. We then change the state of gas to a volume V2, pressure P2, and temperature T2.
We can express this by writing K = nR, where n is the amount of gas in a given volume of gas and R is independent of all variables and is, therefore, a universal constant. We thus have the general gas law:
PV = nRT