Hi,
When ATP is mixed with water it tends to be hydrolized. This chemical reaction can bring forth two possibilities:
1) ATP + H2O ? ADP(adenosine di phosphate)(hydrated) + Pi(hydrated) + H+(hydrated) ?G? = -30.54 kJ/mol (?7.3 kcal/mol)
2) ATP + H2O ? AMP(adenosine mono phosphate)(hydrated) + PPi(hydrated) + H+(hydrated) ?G? = -45.6 kJ/mol (?10.9 kcal/mol)
These two equations show the products of the reaction (the delta G is added cause energy takes a part in the equation).
Hope this helped you.