Let’s learn the laws of thermodynamics. It help us understand why energy flows in certain directions and in certain ways. A lot of the concepts described by thermodynamics seem like common sense but there is a layer of math beneath the intuitive level that makes them very powerful in describing systems and making predictions. Energy is not created or destroyed, it only changes forms from potential energy to kinetic energy to heat energy etc. While we have found this to be untrue on the quantum level, for chemists, it does just fine. However, there seems to be a preferred direction in which energy flows from one form to another in order to understand how we look at the second law. The second law, entropy, is the measurement of disorder in any given system. It introduces a new concept. Entropy is quite difficult to understand but we can most easily describe entropy as disorder. And the second law states that the sum of the entropy is of a system and its surroundings must always increase in other words the entropy or the disorder of the universe is always increasing. Within a system there is also a tendency to go towards higher entropy the classic analogy is that your bedroom will overtime become messy but it won’t suddenly become neat. Another way to look at this is the say the entropy is a measure of how dispersed the energy of the system is amongst the ways that system can contain energy yet another way is to analogize in traffic states to computer code. Let’s take for example an ionic solid compared to the same substance as a liquid clearly the solid state is more ordered and the liquid state is more disordered or higher in entropy to describe the solid state using computer code you would need to include terms to describe the geometry of the lattice the intermolecular distances the precise configuration of every molecule and many other things. But to describe the liquid state you would need to simply describe the volume of liquid and the shape of the vessel because the motion and configuration of the molecules are random. That’s far less information that is needed in coding which is a way of rationalizing why increasing the entropy of a system is thermodynamically favorable. We can look at all kinds of processes to highlight entropic influence. Heat will flow from the hot coffee cup into the table or your hand because the heat energy will be more disordered if more dispersed. This is why heat spontaneously flows from hot to cold and not the other way around, entropy. The third law states that a perfectly Crystaline solid at absolute zero has an entropy of zero, as this is the most ordered state that the substance can be in. Entropy is measured in jewels per kelvin. Note that entropy is not a measure of energy itself but of how energy is distributed within a system. It is enthalpy, the thermodynamic quantity that more accurately describes the energy of a system. Entropy and enthalpy intricately relate to tell us something about the Gibbs free energy of a system. (G) or Gibbs free energy tells us about a spontaneity of a process, whether a process will be spontaneous or not.

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