SME
Physical Chemistry I: Thermodynamics & Kinetics · Problem type
State or path function?
Use this for “A gas goes from state 1 to state 2 by two different routes. Which of q, w, ΔU and ΔS are the same for both?”
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Does its value, or its change, depend on the route taken?
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Around a full cycle every state function comes back to where it started, so its change is 0; heat and work need not be.
Assumptions
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A state function has one value for each state of the system, so its change depends only on where it starts and ends.
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Heat and work are energy moving across the boundary on the way, so two routes between the same states can move different amounts.
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Their sum is not a path function: q + w = ΔU, the same on every route.
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