CHEM 205 lecture 7
• First law of thermodynamics talks about conservation of E
o Doesn’t specify direction or efficiency of a reaction. Doesn’t say
anything against “impossible processes” like cold water becoming cooler
and hot water becoming hotter spontaneously.
• Second law of thermodynamics dictates entropy (no 100% conversion of q into
o “It is impossible for a CYCLIC process whose sole effect=flow of
heatsystem from heat reservoir and for the performance of equivalent
amount of work by the system on the surroundings.
o Wq can be 100%
o But qW will never be 100%, always some heat loss. Eg. Friction.
• For a reversible, non-spontaneous process: ΔS=0----we can only make this
reaction happen if we do work on the system
• For a irreversible, spontaneous process: ΔS>0
o When I say ΔS, I am referring to TOTAL entropy aka. Entropy of the
• Rate has nothing to do with if a reaction is spontaneous or nonspontaneous
• Entropy is a state function where S=q(rev)/T
• Why do we say total entropy is always increasing (or staying the same at the very