First order phase transition (van der waals gas)

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The discussion focuses on the physical explanations of the graphs in the referenced lecture notes, specifically regarding the behavior of Vg and Vl with temperature changes. Vg decreases with temperature while Vl increases, which is linked to the Maxwell construction and the behavior of the p-V curve as it approaches the critical point. As temperature rises, the loops in the theoretical p-V curve diminish until they vanish at the critical point, causing Vg and Vl to coalesce. This coalescence results in a decrease in the distance between Vg and Vl with increasing temperature. Understanding these relationships is crucial for grasping the underlying thermodynamic principles.
jasony
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I am looking at some of the notes but don't quite understand this.

What are the physical explanation of the graphs (Fig 4(a) and 4(b)) on Page 4 ?
http://www.pma.caltech.edu/~mcc/Ph127/b/Lecture3.pdf"

Why V_{g} decreases with temperature but V_{l} increases with temperature?
 
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Anyone who can help? please...
 
Look at the Maxwell construction: When the temperature rises, the two loops in the theoretical p-V curve become less and less pronounced until they disappear at the critical point. At the critical point Vg and Vl coalesce, hence the distance of Vg and Vl has to decrease with temperature.
 
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