Sketch a qualitatively accurate graph of the entropy of a substance

  • #1
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Homework Statement:

All below

Relevant Equations:

All below
Sketch a qualitatively accurate graph of the entropy of a substance
as a function of temperature, at fixed pressure. Indicate where the
substance is solid, liquid, and gas . Explain each feature of the graph briefly.

What you think about?:

dU = -P*dV + Q*dS (1)
V = C*T => dV = C*dT
Nfk*dT/2 + P*C*dT = Q*dS

Nfk/2 + P*C = Q*(dS/dT)

For a solid, i assumed f = 3, for a liquid f = 5 and for the gas, f > 5 (i think is not necessary say the obvious this is a rough approximation)

1596418979115.png
That would be the result.
 

Answers and Replies

  • #2
368
73
View attachment 267215That would be the result.
The liquid and gas phases look about right to me (not 100% sure about the solid region). Usually, I see plots of [itex] T [/itex] vs [itex] s [/itex] for liquids and vapours, so I don't want to comment on that (solid) region as I am not too knowledgeable.
 

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