Enthalpy is a measure of the energy that is not available for work during a thermodynamic process.

The story behind the answer

False. Enthalpy (H) is the system’s heat content: H = U + pV. At constant pressure, ΔH equals the heat absorbed or released, but it does not measure energy unavailable for work. The “unavailable” portion is the T·S term; subtracting this from enthalpy gives the Gibbs free energy, G = H − T·S, which sets the maximum useful (non-expansion) work at constant temperature and pressure.

Memory tip: H for Heat, G for Go (usable work), S for Spread (entropy). Combustion often has large negative ΔH (releases heat), but whether that energy can perform work depends on entropy and temperature via G, not H.