First off I don\'t have a specific question, this is a general question on how t
ID: 1818264 • Letter: F
Question
First off I don't have a specific question, this is a general question on how to answer Thermodynamics questions. I'll give Karma for any help I get and I'll try to give Lifesaver to the best answer. I'm not really sure how they split up the helpful Karma but I'll give that to all other answers. Ok.I'm in a Thermodynamics class right now, and for every question it seems you start by looking up some data, jotting down an equation you know, and doing a random gyration of algebraic know-how to find the answers you need in seemingly no particular order. Does anybody have a system they follow that helps them to know where to start solving a problem? Like key words or information that tells them what type of question is being asked? Whenever I read problem statements it seems like the data given isn't enough or is random and doesn't fit any equations, so I struggle with how to get a problem rolling.
Things such as knowing when a problem needs entropy or enthalpy data, or what type of general energy equation should be used are what I'm talking about. This should be the easy stuff, but my first two thermo classes were taught by... ahem... quacks, and I have missed out on a lot of basic thermodynamics problem solving skills.
Sorry for being long winded and thanks for your help.
Explanation / Answer
I am telling you I used to do in graduation 1. while reading the problem write all the data given in the problem in their appropriate notations. such as V,P,Cp,Cv etc 2. Focus on the phrase where the thermodynamic process is mentioned. write it down after that. e.g. 'reversible isothermal, 'rev . adiabatic ' or irreversible etc 3. There are several equations for several processes. So don't mix them up. Just after writing the name of the process u try to recall the equation corresponding to that particular process. 4. The few things u have to keep in your mind and rest of the other u can derive from those equations. 5. Now try to fit the data with the equation. Always remember the state of the process as whether it is in constant pressure or in const. temp etc 6.There are some equations which are very important and u should keep in mind and rest u can establish first law dU = q + w w= - PdV in general so dU = q - Pdv again dU = CvdT so q = CvdT + pdV..............1 Cv = (du/dt)v Cp = (dH/dT)P and the Gibbs equations dU = TdS - PdV dH = TdS + VdP dA = -SdT - PdV dG = -SdT + VdP dS = q/dT = dH/dT generally in most of the problem they ask to calculate q,w,dU,dH,dG fr isothermal and or adiabatic process. so have a look to those equations and try to recall it. and keep in touch with the thermodynamics equations otherwise u will surely mess them up. so be aware of making mess of equations. hope i made u a little aware of thermodynamics.
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