Maximum Work
The greatest amount of work obtainable from a change of state, achieved only along a reversible path.
Formula / equation
w_max = ΔA; w_max(non-pV) = ΔG
Unit
J
In depth
Any irreversibility — friction, finite temperature difference, or rapid expansion — dissipates part of the available energy as heat and reduces the work recovered. Gibbs energy gives the maximum non-expansion work, which is the figure that matters for batteries and for biochemical energy transfer.
Examples in the real world
A fuel cell approaches the ΔG limit of −237 kJ/mol for hydrogen combustion, far exceeding a heat engine's Carnot limit.