1. Heating Curve H = Cice x T x mass Hfusion= 6.02 kJ/mol x mass
Cice=2.087 J/goC
Hfusion= 6.02 kJ/mol x mass
H = Cwater x T x mass
Cwater=4.184 J/goC
Hvap = kJ/mol x mass
boiling point T
H = Csteam x T x mass
Csteam=1.996 J/goC
melting point
0oC
100oC
steam
water
ice
-20oC
heat added

2. Entropy = S
Entropy is thought of as
disorder
or randomness
dispersal of energy

3. 2nd Law of Thermodynamics
Suniverse
> 0
for spontaneous processes
spontaneous =
no external intervention
Ssystem
Ssurroundings
positional disorder
energetic disorder

4. Energetic Disorder P.E. K.E. random ordered Hsystem 0 <
reactants
P.E.
Hsystem 0
<
products
Hsurroundings 0
>
Ssurroundings > 0

5. Positional Disorder With 1 mole of gas, Not probable (1/2) (1/2) (1/2)
= 1/64 1 2
6.02 x 1023
With 1 mole of gas,
Not probable

6. Positional Disorder Boltzman ordered states low probability low S
RIP
S = k ln W
W = microstates
Boltzman
ordered states
low probability
low S
disordered states
high probability
high S
 Ssystem  Positional disorder
Increases with number
of possible positions
(energy states)
Ssolids
< Sliquids
<< Sgases

7. Entropy (J/K) [heat entering system at given T] convert q to S
Pext = 1.5 atm
E = 0
w = -182 J
q = +182 J
T = 298 K
E = 0
System 2
Pext = 0 atm
w = 0
q = 0

8.  Pext = Pint + dP System 3 reversible process - infinitely slow wr=
P1 = 6.0 atm P2 = 1.5 atm
V1 = 0.4 L V2 = 1.6 L
T1 = 298 K = T2
Pext =
Pint
+ dP
reversible process
- infinitely slow V2
wr=
- Pext  dV
=- nRT dV V  =
- nRT
ln (V2/V1) V1

9. Ssystem Ssurr = - Hsystem Ssystem = qr = 343 J T 298 K T System 1
Pext = 1.5 atm
w = -182 J
q = +182 J
S =
System 2
Pext = 0 atm
w = 0
q = 0
S =
System 3
Pext = Pint + dP
wr =
qr =
S =
-nRT ln (V2/V1)
= J
+ 343 J
1.15 J/K
1.15 J/K
1.15 J/K
Ssurr = - Hsystem
Ssystem = qr T
= 343 J
298 K T

10. 3rd Law of Thermodynamics
Entropy
of a perfect crystalline
substance
at 0 K
= 0

11. Entropy curve S Temperature (K) gas liquid solid vaporization qr T
fusion
Temperature (K)

12. Entropy At 0K, S = 0 Entropy is absolute S  0
for elements in standard states
S is a State Function
Sorxn =
nSoproducts
- nSoreactants
S is extensive

13. Increases in Entropy 1. Melting (fusion) Sliquid > Ssolid
2. Vaporization Sgas >> Sliquid
Increasing ngas in a reaction
Increasing volume of gaseous system
5. Heating ST2 > ST1 if T2 > T1.
6. Dissolution Ssolution > (Ssolvent + Ssolute) ?
7. Molecular complexity number of bonds
8. Atomic complexity e-, protons and neutrons