 ATP is an unstable molecule in unbuffered water , in which it hydrolyses to ADP and phosphate . This is because the strength of the bonds between the phosphate groups in ATP is less than the strength of the hydrogen bonds ( hydration bonds ) , between its products ( ADP and phosphate ) , and water . Thus , if ATP and ADP are in chemical equilibrium in water , almost all of the ATP will eventually be converted to ADP . A system that is far from equilibrium contains Gibbs free energy , and is capable of doing work . Living cells maintain the ratio of ATP to ADP at a point ten orders of magnitude from equilibrium , with ATP concentrations fivefold higher than the concentration of ADP . This displacement from equilibrium means that the hydrolysis of ATP in the cell releases a large amount of free energy . 
