 Welcome back MechanicalEI, did you know that there exists a mnemonic diagram designed by Max Bond just to remember some thermodynamic relations? This makes us wonder, what are thermodynamic relations? Before we jump in, check out the previous part of this series to learn about the applications of entropy. Now, thermodynamic relations refer to the famous Maxwell relations which apply for a pure substance undergoing an infinitesimal reversible process defined by four equations. These equations apply to the four thermodynamic properties and are exact differentials of the type dz equals mdx plus ny which can be represented as dow m upon dow y with x constant equals dow n upon dow x with y constant. Using this method on the four equations, we get the Maxwell equations. During phase transactions like melting, vaporization and sublimation, the temperature and pressure remain constant while the entropy and volume change. The Clausius-Clapeyron relation helps in differentiating a discontinuous phase transition between two phases of matter denoted by a coexistence curve on a pressure-temperature diagram. It does so by giving the relation between the slope of the tangents to this coexistence curve. There is a temperature change in a real gas or liquid when it is forced through a valve or porous plug while being kept insulated so that no heat is exchanged within the environment. This effect is called the Joule-Thomson effect and is widely exploited in thermal machines such as generators, heat pumps and air conditioners. Hence, we learned about what the thermodynamic relations are, then moved on to the Clausius-Clapeyron and finally saw what the Joule-Thomson effect is. So, like, subscribe and comment with your feedback to help us make better videos. Thanks for watching. Also, thanks a lot for those constructive comments. You helped the channel grow. So, here are the top mechanical EIs of our last videos. In the next episode of Mechanical EI, find out what expansion and compression are.