This equation relates the standard-state free energy of reaction with the free energy of reaction at any moment in time during a reaction.
`Delta _G^0 = -RT ln( K_a)`
the most important thermodynamic property is one termed the free energy of a reaction.Understanding the free energy of a reaction also allows one to determine under what conditions a biological reaction will proceed, in what direction the reaction will occur and the position of equilibrium and to compute the equilibrium constant (Keq) of the reaction.