1. Thermodynamics of surfaces and interfaces
Atkins (ed. 10 and 11): §16C C.4
Atkins (ed. 9): §
Atkins (ed. 8): §
Study Guide: P.14

2. Na2ClO3 crystals in solution

3. Large crystals grow; small crystals dissolve
T = 1 day 3

4. Large crystals grow; small crystals dissolve
Wilhelm Ostwald
Ostwald ripening
(1896)
T = 0
T = 1 day 4

5. Equilibrium: one single crystal
T = 1 day
10 days
30 days 5

6. Equilibrium: one single crystal
T = 1 day
10 days
30 days 6

7. Gibbs-Thomson effect
Interfacial (free) energy between two phases

8. Gibbs-Thomson effect Interfacial (free) energy between two phases
relevant for P >1
P =1
P =2,3
P =2,3

9. Laplace equation: γ surface free energy (Jm-2)
out in
Equilibrium:

10. Laplace equation γ r γ
r+dr
equilibrium
Laplace
equation

11. Surface tension γ (Jm-2 = Nm-1)
water

13. Surface tension and capillary action
Pressure of
liquid column
of height h
Laplace equation
equilibrium
capillary action
Adhesive force between fluid and capillary

14. Surface tension and capillary action
γ counteracts
the adhesion
between liquid or gas
and capillary

15. Surface tension and wetting
specific
work (J/m2)
of adhesion
(γ is always trying to reduce the corresponding surface)
horizontal
Force (N/m)
balance
(equilibrium)

16. Surface tension and wetting}
Work (J/m2)
Force (N/m)
partial dewetting
partial wetting

18. Kelvin equation (nucleation barrier for condensation (g  l))γ
Pout
Laplace equation
Pin l g
equilibrium
constant T
Kelvin equation
small droplets evaporate
condensation nucleation barrier
 Pg > P*

19. nucleation of phase α(l) from phase β(s)
revert to Gibbs free energy
classical nucleation theory
spherical nucleus, radius r
driving force:
surface free energy: γ
molar volume: Vm γ β α
Free energy
gain
cost

20. nucleation barrier depends on supersaturation
nucleation barrier and critical radius Δμ Δμ Δμ Δμ Δμ
nucleation barrier depends on supersaturation (Δμ = Δμ(T))
-low Δμ : no nucleation
-high Δμ : easy nucleation