BI110 Lecture Notes - Lecture 22: Gibbs Free Energy, Activation Energy, Thermodynamics
Document Summary
Total energy = useable energy + unusable energy. Usable energy is called free energy (g) H = g + ts (t = temperature) The amount of free energy (g) changes when a system changes. The change in free energy ( g) (cid:272)a(cid:374) (cid:271)e (cid:272)al(cid:272)ulated fo(cid:396) a(cid:374)y (cid:396)ea(cid:272)tio(cid:374) As a reaction goes to completion, it is influenced by two factors: changes in energy content, changes in entropy. More simply: g = gfinal ginitial. G (cid:272)a(cid:374) (cid:271)e used to p(cid:396)edi(cid:272)t (cid:449)hethe(cid:396) a (cid:396)ea(cid:272)tio(cid:374) is spo(cid:374)ta(cid:374)eous: fo(cid:396) spo(cid:374)ta(cid:374)eous (cid:396)ea(cid:272)tio(cid:374)s, g < 0, rea(cid:272)tio(cid:374)s (cid:449)ith g > 0. Gibbs free energy (g) can be calculated for any molecule aa+bb cc + dd. The g of c + d = gfinal. In exergonic reactions, net change in gibbs free energy is negative and energy is released from the system. In endergonic reactions, net change in gibbs free energy is positive, and energy must be added to the system.
