Chemistry 2214A/B Lecture Notes - Lecture 12: Ideal Gas, Isobaric Process, Phase Transition

• School: Western University
• Department: Chemistry
• Course: Chemistry 2214A/B
• Professor: T.K.Sham

Document Summary

First law describes the energetic for a process but does not tell us whether or not a process will occur naturally. A new parameter and a different law are needed to track the spontaneity of the process, it is the entropy, s, and the second law of thermodynamics. In nature, matter has a tendency to disperse. i. e. order disorder. Energy also has a tendency to become dispersed. E. g. heat (random thermal energy) cannot be 100% converted into work (organized energy) The entropy of an isolated system increases during a spontaneous process, s > 0; To calculate the s between two states, always look for a reversible pathway. S is the same for both reversible and irreversible isothermal expansion/compression of a gas from the same initial to the same final state. Since s is a state function, we always calculate it according to the reversible pathway: reversible vaporization at tb. p. and pvap (at tb. p.