The relation between the standard free energy and the equilibrium constant of a reaction can be readily derived. At equilibrium. AG=0 Equation 6 then becomes 0=△G°+ RTog [CJ[D] A][B] and △G=- RT log ICJ[D [AJIB] (8) The equilibrium constant under standard conditions, Keo, is defined as K [C][D [A][B] (9) Substituting equation 9 into equation 8 gives AG.--RTloge Keq =-RT InKeq (10) △C"=-2.08r10Km△G!RT (11) hich can be rearranged to give Ken=e eq=10-42.303R7 K Substituting R= 1.987 X 10-3 kcal mol -I deg I and T=298K(corre- sponding to 25C) gives eq=10-4G°/1.36 K (13)K´ e △G○′ /RT RT lnKeq ´ eq