What is the difference between enthalpy and entropy?
1 Answer
Almost... everything. Letter, units... everything except that they're state functions and expressions of energy.
color(blue)(DeltaH) = DeltaU + Delta(PV)
= q + w + Delta(PV)
= q cancel(- PDeltaV + PDeltaV) + VDeltaP + DeltaPDeltaV
= color(blue)(q + VDeltaP + DeltaPDeltaV) where
U is internal energy,q is heat flow,w is expansion/compression work, and of course,P is pressure andV is volume.
The units for the generic enthalpy are usually in
This makes enthalpy the heat flow in a closed system, plus the amount of expansion/compression work done via a change in pressure.
color(blue)(DeltaS >= q/T)
color(blue)(DeltaS = (q_"rev")/T)
The units for the generic entropy are usually in
This makes entropy equal to the amount of reversible heat flow possible per unit temperature.
