How does atp hydrolysis release energy?

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Answer 1 · 2015-06-25T23:53:01

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

The equation for hydrolysis of ATP is

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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.