Isothermal Process State Equation Pv Constant — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Isothermal Process State Equation (PV = constant) Applies to ideal gases undergoing a reversible isothermal (constant temperature) process within a closed system. Start with the Ideal Gas Law: PV = nRT. Assume n (moles) is constant for a closed system. Assume T (temperature) is constant for an isothermal process. Combine constants: PV = constant. Equate initial and final states: P 1 V 1 = P 2 V 2. Temperature must remain constant. The amount of gas (moles) must remain constant. The gas must approximate ideal gas behavior. Assuming no heat transfer occurs (Q = 0) because temperature is constant; actually Q = W. Confusing isothermal (constant T) with adiabatic (Q = 0). Applying the formula when phase changes occur.