I know the difference between first and second order phase transition in terms of the discontinuity of the derivatives of free energy.
I am curious to know what happens as the system is viewed. Suppose a liquid is heated in a container. For a first order phase transition, a liquid, which has a finite volume (but takes the shape of the container), will consume the volume of the whole container when it turns into gas.
What happens in case of a second order phase transition?
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Suppose I take a system in state P ($T>T_c, P > P_c$) or Q ($T > T_c, P < P_C$) in the phase diagram. Will it have a finite volume, or will it consume the whole volume of the container? In a second order transition, can a fluid "continuously" transit between a state with finite volume and a state consuming all volume of the container (in other words, infinite volume when allowed to grow)?
It seems to me that the property of whether the fluid will have finite volume or not, cannot change continuously.