The equation of state describes the relationship between pressure, volume, and temperature of a substance in a given state. For an ideal gas, it is expressed as PV = nRT, where P is pressure, V is volume, n is moles, R is the gas constant, and T is the absolute temperature.

Class 11 Physics Chapter 11 Thermodynamics deals with the principles of heat energy and its conversion to work. It covers the first and second laws of thermodynamics work done by heat engines and the Carnot cycle. The chapter also explains specific heat capacities of gases and introduces the concept of entropy in thermodynamic processes.