Saturday, May 30, 2009

Chemistry comes alive!

In Monday's lecture (draft here) I want the students to understand the following key points about applying thermodynamics to chemistry:
  • Its all about entropy of mixing. Consequently, chemical reactions never go to completion.
  • The equilibrium constant K quantifies the extent to which a reaction has gone to completion.
  • K and its temperature dependence allow one to determine the change in Gibbs free energy, enthalpy, and entropy, associated with the reaction.
  • All thermodynamic functions are defined relative to a standard state (temperature, pressure, and concentration).
I like to show a few cool video demonstrations from the Chemistry Comes Alive series from the Journal of Chemical Education. I have CD's volumes 2 and 3, which have lots of material relevant to physics too (magnetism, superconductivity, phase transitions, critical points, ...).

When nitrogen triiodide, the dark colored solid, is dry, it is very sensitive to touch or any vibration. Simply touching it with a feather causes it to explode or detonate. One detonation causes another to occur. One product of the reaction is violet iodine vapor.

A mere touch of a feather ... .. causes dry nitrogen triiodide to explode.


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