The trick is to realize that the subject of statistical mechanics understands the ideas of “order” and “disorder” very differently than we do. ![]() But a system in equilibrium has the maximum possible amount of entropy. Meanwhile, entropy is a measure of disorder. Equilibrium is when all things are in balance - that sounds like order. When I first learned about this, I found it very counterintuitive. This seesaw is in equilibrium - albeit an unstable one - because all forces are in balance. A system that is closer to equilibrium has more entropy than a system that is farther from equilibrium. The significance of entropy is that it tells us how close a system is to equilibrium, a state in which all opposing processes are in balance. ![]() But why do we care about this quantity? Why does entropy matter? Entropy (S) is measuring the same thing as W, but on a much more practical scale.Īgain, entropy is an indirect measure of W, the number of microstates that could produce the system’s current macrostate. (We also had to correct for the units.) But after making these adjustments, the number S is small enough that we can work with it. That’s why we have to take the natural log of it and why we have to multiply it by Boltzmann’s constant, which is an infinitesimally small number. Entropy is an indirect measure of how many microstates could produce the system’s current macrostate.įor any macroscopic, real-world system, the number W will be astronomically large, probably well over 10^(10¹⁰). As such, the entropy (S) is just a modified form of W. And Boltzmann’s equation defines the entropy of the system to be the natural log of W, multiplied by Boltzmann’s constant (k). How many ways could you arrange all the molecules in a room? (Image from )įor a given system in a given macrostate, the number W refers to the number of distinct microstates that could produce that same macrostate. Heat is one of two ways of transferring energy to a system, work being the other. All of those transfers of energy are classified as heating. And latent heat release is when something changes from gas to liquid, or from liquid to solid, and releases energy by doing so. Radiation is energy traveling through space (like how the sun heats the earth). ![]() Conduction is when a warmer object heats an adjacent cool object. Heat is when you transfer energy to a system by means of conduction, radiation, or latent heat release. In science, heat is a process, while temperature is a quantity. ![]() In fact, in the context of science, “heat” is really a verb rather than a noun. Heat and temperature are not the same thing. After briefly discussing heat and temperature, I will explain the concept of entropy I will then discuss the Second Law of Thermodynamics (2nd Law of TD) and its significance. In this article, I will shed some light on these terms. All systems are assumed to be closed systems unless stated otherwise.)īut this mathematical statement leaves so many questions unanswered most importantly, I still haven’t explained what entropy is. (I explained the concept of a “system” in my previous post. Where δQ is the heat added to the system, T is the ambient temperature, and dS is the change in the system’s entropy.
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