Isobaric Process

Isobaric process: pressure stays CONSTANT (ΔP = 0).

On PV diagram: HORIZONTAL line.

Work done by gas: W = P·ΔV — simple area calculation.

Heat absorbed: Q = nC_p·ΔT, where C_p = (f/2 + 1)R = molar specific heat at constant P.

Change in internal energy: ΔU = nC_v·ΔT (always, for ideal gas).

Volume and temperature linked: V/T = constant (Charles's law).

Examples: water boiling in an open pot (P_atm constant), gas expansion against atmospheric pressure.

C_p > C_v because some heat goes into expansion work (Mayer's relation: C_p − C_v = R).