1. The Nernst heat theorem was formulated by Walther Nernst early in the twentieth century and was used in the development of the third law of thermodynamics. == The theorem == The Nernst heat theorem says that as absolute zero is approached, the entropy change ΔS for a chemical or physical transformation approaches 0. This can be expressed mathematically as follows: lim T → 0 Δ S = 0 {\displaystyle \lim _{T\to 0}\Delta S=0} The above equation is a modern statement of the theorem. Nernst often used a form that avoided the concept of entropy. Another way of looking at the theorem is to start with the definition of the Gibbs free energy (G), G = H − T S {\displaystyle G=H-TS} , where H stands for enthalpy. For a change from reactants to products at constant... from wikipedia.org