Physical Chemistry II: Problem using Cyclic Rule
Equations of state such as the ideal gas law (PV=nRT) relate Pressure (P) as a function of Temperature
(T) and Volume (V). There are many other functions of this type:
P(T ,V )
dP = dT +
Internal Energy (U), Heat (q), and Work (w)
These are examples of thermodynamic quantities that can be applied to
chemical reactions or transformations.
Question: Which of these are state functions and which are not?
First Law of Thermodynamics:
A Group is a set of elements:
1. Products of elements must generate other elements of the group
Products do not necessarily commute
If they do, the group is Abelian
2. Identity element must be present (E)
3. Associative Law must hold: A(BC)=(AB)C
Physical Chemistry II: Class project
Thermodynamics of Ideal Gas Manipulations
For this exercise, we will examine the reversible expansion and compression of an ideal monatomic gas.
We begin with one mole of helium at 300. K (point A on the graph). The sy
A set of nuclear coordinates defines a particular symmetry
for a molecule which is given by its symmetry operations.
These act to exchange equivalent atoms.
The symmetry operations present in a given molecule are
elements of a group.
Nuclear Magnetic Resonance Spectroscopy
Nuclei have an intrinsic spin angular momentum just like electrons. The
solutions for nuclei are structured in a similar manner:
I 2 = I ( I + 1) 2
I z = mI
nuclear angular momentum vector
spin quantum number (
Experimental Absorbance can be expressed using the equation:
A = log T = log = [J ] l
molar absorption coefficient
[J ] concentration of the sample
path length of the cell
The molar absorption coefficient depends on wavelength. You can
Physical Chemistry II: Work involved in a reversible process.
State Function: Property that only depends on the final state of a system (no need to know how it
arrived there). Examples: Energy (U), Enthalpy (H), Entropy (S), Free Energy (G)
U = q + w
If we restrict ourselves to processes that only involve PdV-type work:
U = q PdV
Furthermore, if we consider only processes done at constant pressure:
U = q P V
The heat associated with such a process would
The Equilibrium Condition
Terms and definitions:
o extent of reaction ()
o reaction quotient (Qp and Qc)
o equilibrium constant (Kp and Kc)
o chemical potential A =
o Gibbs Energy change of formation at 1.0 bar (fGo)
o Gibbs Energy change for one m
With these in hand, we can derive Maxwell Relations by using the following
F ( x, y )
F ( x, y )
As an example, use Gibbs Energy (G) as the function and its natural
variables of T and P to find:
Derive the other Maxwe
Entropy (S) is a measure of disorder. Heading toward disorder is a driving force in nature.
Suniv = S sys + S surr
S surr =
+ process is spontaneous
S sys =
reverse process is spontaneous
0 process is reversible
Recall discussion from your General Chemistry II course:
Cs specific heat capacity is the amount of energy needed to raise one gram of a substance one oC.
Example: Cs(water) = 1.0 cal/g-oC (it is how the calorie is defined)
q=mass x Cs x T
The actual heat
What Does the Free in Free Energy Mean?
Concepts and Terms:
Gibbs Energy (G) associated with a constant PT process
Helmholtz Energy (A) associated with a constant VT process
non PdV work and efficiency
reversible versus spontaneous processes
Molecular Energies and Partition Functions for Diatomics
Partition Function for Molecule (q)
(nx2 + n y2 + nz2 ) h 2
2 m k T 2
8 m V 2 / 3
see practical version here.
J ( J + 1) h 2
8 2 I