Write down the reaction for the catabolism of ATP: Does that occur by dehydration or hydrolysis? Is energy released or required when ATP is broken down? Solution Answer: ATP catabolism: ATP + 2H2O ----------> ADP + Pi (inorganic phosphate) + Energy (G = -30.5 kJ/mol of ATP) The above reaction is hydrolysis. It is an energy yielding process. ATP hydrolysis, water is used to split apart ATP to create ADP (adenosine diphosphate) to get energy..