PhysChemBasics#4: Affinity 101 The 1st and 2nd law are statements about energy and entropy in the universe. We can measure the change in energy and entropy during a process and are also able to calculate these quantities using thermodynamic tables. We may combine energy and entropy using the Gibbs Helmholtz equation and arrive at Gibbs Free Energy which is a measure of instability. It tells us whether or not a process will run spontaneously.