The metastable state: and Masatsugu Sei Suzuki Department of Physics, SUNY at Binghamton (Date: November 10, 2019)

3.0

vr

2.5

g

2.0 e pr 0.75

Super cooled state B

1.5 d

c 1.0 K

b A Super heated state l a 0.5 tr

0.85 0.90 0.95 1.00

The binodal line is known as separation line, since it separates the homogeneous gas and liquid states. For parameters within the binodal line the equilibrium shows two-phase co-existence. In the region between the binodal line and the line, the homogeneous system is in a metastable state.

3.0

vr

2.5 Gas

p 0.70 r g

pr 0.75 2.0 e

pr 0.80

pr 0.85 B

pr 0.90 1.5 d

pr 0.95

c

1.0 K

b A a l t 0.5 Liquid r

0.85 0.90 0.95 1.00

3.0

vr

2.5

Gas

2.0 g pr 0.80 e Super cooled state B

1.5 d

c 1.0 K

b A a l Super heated state 0.5 Liquid tr

0.85 0.90 0.95 1.00 e: the intersection of the ParametricPlot (denoted by black line) and the K-e line (binodal line) d: the intersection of the ParametricPlot (denoted by black line) and the K-d line (spinodal line) c: the intersection of the ParametricPlot (denoted by black line) and the K-c line b: the intersection of the ParametricPlot (denoted by black line) and the K-b line (spinodal line) a: the intersection of the ParametricPlot (denoted by black line) and the K-a line (binodal line)

Point a: thermal equilibrium Point e: thermal equilibrium Point c: intermediate between the points a and b ( of point c is the same as that of points and e).

(P , T ) T    PPTV  ( , ) (P , V )       P .    V T  V  T  ( V , T ) ( , ) T     (P , V ) P  V

P  T  At the points b and d, we have    0 (isothermal process) and    0 (isobaric V  T V  P process).

In the thermal equilibrium, during the cooling process at fixed pressure pr , we have the path (g- e-c-a-l). Super-heated state: Super-cooled state:

  Fig. Isothermal curve. t t r . p p r.   Point a: v v1( t ) , p p r   Point b: v vm1( t ) , p pm1( t )   Point c: v v2 ( t ) , p p r   Point d: v vm2 ( t ) , p pm2 ( t )   Point e: v v3 ( t ) , p p r

How to draw these graphs

 (1) ContourPlot of pr 0.70, 75, 0.80, 0.85. 0.90, and 0.95 in the (tr , v r ) plane.

8 1 3 p t  r3 r 1 v 2 (v  ) r r 3

(2) Line ( K-e): Plot of v3 ( t ) (binodal line)

(3) Line ( K-d): plot of vm2 ( t ) (spinodal line)

(4) Line ( K-c): plot of v2 ( t )

(5) Line ( K-b): plot of vm1( t ) (spinodal line)

(6) Line ( K-a): plot of v1( t ) (binodal line)

Physical meaning of v1( t )

We make ParametricPlots of {,t v1 ()} t , {t , v2 ( t )} , {t , vm1 ( t )} , {,t vm2 ()} t , as well as the  ContourPlot of pr 0.70, 75, 0.80, 0.85. 0.90, and 0.95 in the (tr , v r ) plane.

10

Gas 8

g

6 pr 0.30 e

0.4

4 A 0.50

d 0.6

0.7

2 B 0.8 c 0.9 K1.0 1.11.1 l a b tr Liquid vr 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 10

pr 0.30 vr Gas 8

g

6 e

Super cooled state

4 A

d

2 B c K

l a b Liquid Super heated state t 0 r 0.5 0.6 0.7 0.8 0.9 1.0

It is well known that systems exhibiting first-order phase transitions can exhibit hysteresis in the transition temperature and therefore in other physical properties upon cooling and warming, where the transition temperature is lower on cooling (supercooling) and higher on warming (superheating) than the equilibrium transition temperature.

Water:

 Critical point: Tc 647 K. Pc = 22.064 MPa = 217.7 atm

Boiling point: P = 101.325 kPa = 1 atm. T = 373 K.

P   3 pr 4.592 10 Pc

60

50 vr pr 0.05

40

30

20

10

0 tr Super heated state

10 0.2 0.4 0.6 0.8 1.0

60

50 vr pr 0.05

40

30

20

10

0 tr

10 0.2 0.4 0.6 0.8 1.0