Free Energy & the Equilibrium Constant

Paul Andersen explains how thermodynamic and equilibrium reasoning can be related through changes in free energy and the equilibrium constant.  When the delta G is negative the reaction shifts to the right or favors products.  When the delta G is positive the reaction shifts to the left or favors reactants.  In biological systems exergonic reactions (like cellular respiration) can be linked to endergonic reactions (like the production of ATP).