How does atp hydrolysis release energy?

1 Answer
Jun 25, 2015

#"ATP"# hydrolysis releases energy because the products are more stable than the reactants.


The equation for hydrolysis of ATP is

There are three reasons why energy is released upon hydrolysis.

1. Electrostatic repulsion

The adjacent negative charges repel each other.

The molecule can achieve a lower energy state by hydrolysis, which allows the phosphate groups to separate from each other.

2. Increase of Entropy

The equation is

#"ATP"^(4-) + "H"_2"O" → "ADP"^(3-) + "P"_i^(2-) + "H"^+#

We are producing three moles of particles from two moles of reactants.

Entropy is increasing.

Since #ΔG = ΔH –TΔS#, free energy is decreasing and the formation of products is favoured.

3. Resonance stabilization of products

The phosphate groups in #"ATP"^(4-)# have seven resonance contributors.

The phosphate groups in #"ADP"^(3-)# have five resonance contributors, but the #"P"_i^(2-)# has three resonance contributors.

The products have more resonance stabilization than the reactants, so the reactants are in a lower energy state.