Thermodynamics _____ 7.0 Introduction Thermodynamics is a branch of physics, which deals with energy and work of a system. It was first studied in the 19th century as scientists were first discovering how to build and operate steam engines. Thermodynamics deals with the large-scale response of a system in microscopic change, which can be Thermodynamics is the branch of physics that deals with the concepts of heat and temperature and the inter -conversion of heat and other for ms of energy. Thermodynamics is a macroscopic science. It deals with bulk systems and does not go into the molecular constitution of matter. In fact, its concepts and laws were formulated in the Joule's Law leads to an important conclusion concerning the internal energy of an ideal gas. If a gas neither does external work nor takes in or gives out heat, dq = 0 and dw = 0, so that, by the First Law of Thermodynamics, du = 0. According to Joule's law, under these conditions the tem-perature of the gas does not change, which implies Second Law of Thermodynamics and can be stated as follows: For combined system and surroundings, en-tropy never decreases. Actually, it always increases. This is really what makes things happen. The fi rst law of thermodynamics, that energy is conserved, just ells us what can happen; it is the second law that makes things go. The First Law of thermodynamics The Energy is conserved The total energy of a system and its surroundings is constant In any physical or chemical change, the total amount of energy in the universe remains constant, although the form of the energy may change. Biological Thermodynamics