In reaction there is a Gibbs Free energy change. I'm still not sure what this means as in my secondary school years we just learned of one component of it which is the enthalpy change. That was simple as it just showed how much heat was released or absorbed. But with Gibbs Free energy, i don't really know what's going on. My teacher said that it represents the free energy to do non expansion work. But in a reaction we would definitely get the ΔH from it and no more or less than that. So how can energy be "taken away" for the TΔS component? So I don't quite understand the sentence that it is the free energy to do non expansion work actually. We are still in a basic chem course so we do not know or understand any mathematical derivatives so I'm hoping to get a answer in a more physical sense. Thanks in advance for the help.