Today I am giving a
lecture to a second year undergraduate physics class on "Thermochemistry and the Third law". A few highlights and questions are:
- A key idea is that of reference states. All thermodynamic state functions (entropy, internal energy, ...) must be defined relative to some reference.
- The path independence of changes in thermodynamic state functions means that one can calculate changes (e.g., in the enthalpy) via intermediate reactions.
- The third law allows definition of a convenient reference state (T=0).
- Is there a clear way to understand and explain that the "heat of reaction" is the enthalpy change? I still find this a bit confusing. [But pages 33 and 34 of Schroeder's Introduction to Thermal Physics has a helpful discussion].
But, the coolest part of the lecture is the explosions! After all, isn't that is what chemistry is all about? I have some great
Chemistry Comes Alive videos of different chemical reactions. Watch the
Nitrogen Tri-iodide reaction (detonation)!
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