Stability
Diannan Lu
Department of Chemical Engineering
Metastable States
U
U
Left stable
U
Equilibrium
U
Left metastable
Limit of stability
Common occurrence:
A thermodynamic system can be taken beyond the point of equilibrium into the metastable region.

Calculus of Thermodynamics
Diannan Lu
Department of Chemical Engineering
Fundamental Equation
From Postulate 1, we know that we can write :
U = U ( S,V, N1 , N 2 ,!, N n )
Energy Equation
S = S (U,V, N1 , N 2 ,!, N n )
Entropy Equation
Why?
V and S can al

Energy and First Law
Diannan Lu
Department of Chemical Engineering
Work Interactions
Mechanical Work:
W =
x2
x1
(
!" !
!
Fs d x
)
Boundary forces
!"
!
Fs
!
z
a rigid body
)
!"
!
body forces Fb (Centrifugal, gravitational,
inertial, coulombic etc)
If a ri

Reversibility and Second Law
Diannan Lu
Department of Chemical Engineering
Starting from Postulate 3
When we presented Postulate 3, we implied that NOT all processes between two states of a
closed system are adiabatically accessible.
Q: Which processes ar

Chapter 7
Legendre transforms and other potentials
7.1
New thermodynamic potentials from baths
We began our discussion of equilibrium by considering how the entropy emerges for
isolated systems, finding that it is maximized under constant
conditions. In
p

Legendre transform in two-dimensional thermodynamics
Haynes Miller
Fall, 2008
The Legendre transform is a useful device for producing new state
functions from old ones. In thermodynamics, it is usual to employ a
slight variant, diering by a sign from the