Download Phenomena at curved surfaces

Advanced Surface chemistry (2013, 2nd semester)
Graduate course : # 458.622 (Core course)
Credit : 3
Class hour: Tue. & Thr. 3:30 - 4:45 am
Class room: 302-808
Lecturer: Prof. Jihwa Lee (Office Rm. 302-920, Tel: 880-7076)
•
•
Textbooks
Introduction to Colloid and Surface Chemistry 4th Ed:
Duncan J. Show (John Wiley, 1994). Required.
Principles of Colloid and Surface Chemistry 3th Ed:
P.A.Hiemenz (Marcel Dekker, 1997) Recommended.
Reference
1. Introduction to surface chemistry and catalysis: G.A.Somorjai (John Wiley,
1994)
2. Low Energy Electron and Surface Chemistry : G. Ertl & J Küppers ( VCH,
1985)
3. Physical Chemistry of Surfaces: A.W. Adamson (John Wiley, 1982)
•
•
•
Grading
Midterm and final exams ( 25 % each)
1 term paper and poster presentation (30 % each)
Homework ( 20 % )
Topics to be covered
1.Thermodynamics of surface
2.Phenomena at curved surfaces
3.Liquid-gas and liquid-liquid Interface
4. Adsorption and desorption
5. Surface reactions and heterogeneous catalysis
6.Surface spectroscopy
7. Preparation of colloids
8. Kinetic properties of colloids
9. Optical properties of colloids
10. Charged interfaces & Electro-kinetic phenomena
11. Colloid stability
Ch.1 Thermodynamics of surfaces
1.
2.
3.
4.
5.
Surface thermodynamic quantities
Surface tensions of liquids
Intermolecular interactions
Measurements of surface tension
Surface tensions of solids
Surface thermodynamic quantities
Molecules at surface vs. in the bulk
•
•
•
•
Molecules (or atoms) at the surface are in a quite different chemical environment
compared to those in the bulk in terms of intermolecular interactions.
The surface molecules have less number of neighbors to interact
with compared to those in the bulk.
The interactions are attractive in liquids and solids.
Therefore, the surface molecules are in a unstable state with a
higher free energy.
wire
Extension of a soap film
•
•
Extension of the film requires work w
dG = dw = f dl → ΔG = f l
l
f
soap film
Intermolecular interactions
1. van der Waals (Dispersion force)
V(r) = - A/r6
2. dipole-induced dipole
3. dipole-dipole
4. Hydrogen bonding
Relative magnitude
1<2<3<4
Tb of gases (K)
He Ar Xe
4.2 87.3 165
NH3
230.7
H2O
373
C10H8
491
Interaction energy of Ar-Ar
E field by a static electric dipole
γ of various materials
Tm(Pb) = 601 K, fcc metal
Crystallographic orientation
dependence of γ of Pb
FCC (Ar, Ni, Pd, Cu, Ag, Au)
Correlation between
γ and ΔHsub
T = Tm
Critical point
At T = Tc
• Not a liquid, not a vapor
• Condensation and vaporization
occur rapidly.
• Local fluctuation of density
• No surface tension at T = Tc
Empirical equations proposed
• γ = γ0 (T - Tc)n, where Tc is the critical T and γ0 is the surface tension at 0 K.
n ~ 1 for metallic liquids and n> 1 for organic liquids.
• γ Vm2/3 = a (T–Tc) proposed by Eötvös, where a is a constant.
• γ (Vmx)2/3 = a (T–Tc – 6) by Ramsay and Shields, where x is the degree of
association of the liquid (ex: x = 2 for acetic acid); most satisfaoctory