CHM135H1 Lecture 29: 21/11/16 CHM135H1 F LEC0101 Lecture 29 Notes
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Chm135h1 f - lecture 29 - chapter 17 (2) Second law of thermodynamics: heat always flows from hotter to colder body if no work is done (this is simply another way of stating the law) At the molecular level, rapid motion of molecules in a spreads out (like jumping flea model) into b and not vice-versa. Entropy is expressible in terms of reversible heat flow. Reversible means a quasi-equilibrium process: system remains in equilibrium during process. Can be shown that s is a state function. Viewing entropy as a degree of disorder , can expect ssys > 0 when the system undergoes a process in which: temperature increases, volume increases or pressure decreases, number of moles increases through a reaction. Examples: the temperature of a solid decreases: ssys < 0, a diatomic molecule dissociates at constant temperature ssys > 0, ethyl alcohol evaporates: ssys > 0.
