And that involves studying things like Gibbs free energy which involves enthalpy and entropy, as well as studying things like activation energy of that chemical reaction. Now, because enzymes act on chemical reactions, if we are are to actually understand how enzymes behave and act on those chemical reactions, we also have to study the GIBS free energy and the activation energy of that chemical reaction. So let's begin by discussing gifts free energy. Then we'll look at activation energy and we'll finish off with how the enzyme actually affects these two quantities. So let's begin by supposing that we have the following hypothetical reaction. So we have reactants being transformed into products.