1. Surface Chemistry
Jurusan Kimia
Fakultas MIPA Universitas Jember

2. Surface Chemistry
The study of physical and chemical phenomena that occur at the interface of two phases, including solid-liquid interfaces, solid-gas interfaces, solid-vacuum interfaces, and liquid-gas interfaces

3. Gas-Liquid and Liquid-liquid Interfaces

4. Phenomena in Surface Chemistry
Wetting, Spreading and Penetration
Foam Breaking in Aqueous Systems
Solubilization
Rheological Effects in Surfactant Phases

5. Surface Tension, 
an effect within the surface layer of a liquid that causes that layer to behave as an elastic sheet

6. Surface Tension, 
Ketika mengisi gelas dengan air, air tidak tumpah meskipun permukaannya sedikit melebihi bibir gelas
Kenapa air tidak dapat tumpah?
A reason is that water has force to round of itself and remains at the border of cup by shaping an arch. The force to round of itself (to reduce area of surface) is Surface Tention.
Unit of surface tentions is “mN/m” now. Once “dyne/cm” was being used and the scale of those units are same

7. Surface Tension Water Bead or Dome Penny Water Molecule O O OH
Water Molecule O H O H O H
Water molecules are too small for us to see with our eyes alone, but they are composed of one Oxygen (O) atom and two Hydrogen (H) atoms. This is why water is commonly called H2O. O H O H O H O H O H O H O H O H
Penny
Have you heard the saying opposites attract? In a way the atoms that make up a water molecule are kind of like magnets. The hydrogen atoms are positively charged and the oxygen atoms are negatively charged so the water molecules are attracted to each other. This attraction causes the molecules to want to “stick” together and form a dome on a waterproof surface. O H --
Attraction O H +

8. Surface Tension Soapy Water Plain Water Penny Penny O O O O O O O O OH O H O H O H O H O H O H O H O H O H O H O H O H O H O H O H O H O H O H O H O H O H
Penny
Penny
Soap Molecule
In our new model, the blue rectangle represents a soap molecule. Soap molecules act as a “barrier.” When soap is present in the water, the water molecules have a harder time attracting each other so surface tension is reduced. As a result, fewer water molecules will fit on the same penny.

9. Surface Tension as a Force
caused by the attraction between the molecules of the liquid by various intermolecular forces

10. Surface Tension as a Surface Exess Free Energy
γ= 𝜕G 𝜕A P,T

11. Essential of Surface Tension
It originates in Intermolecular forces between molecules.
In the bulk, intermolecular forces work every direction and keep balance
On Surface, the balance is off and molecules exposed in the surface are pulled inside
The surface molecules demand others for interaction and surplus energies generated there, which is Surface Tension.
Surface tension is peculiar physical property of each material has

12. Surface Tension and Wettability
If the surface tension of a target liquid is large...
Force to make the liquid round of itself will be strong
The liquid will be apt to be repelled by solid surfaces
Contact angle results larger  wetting becomes worse
If the surface tension of a target liquid is small...
The liquid will allow to wet over the solid surface
Contact angle results smaller  wetting becomes better.
It will contribute better sreading and permeating

14. Applications of Surface Tension
Evaluation focusing to liquids
Abality of surfactant to decrease S.T.
Wettability, permeability between solid and liquid
Permeation to clearance, fibers
Ink, surfactant
Coating
Characterization of liquids
Emulsification
Dressing, mayonaise, cosmetics
Quality control of detergent, guilt
Management of change cycle

15. Liquid Interfaces
For lotions with mineral oil base to spread freely and evenly on the skin, its polarity and spreading coefficient should be increase by the addition of surfactant

16. ℎ= 2 𝛾 𝑙𝑎 𝑐𝑜𝑠𝜃 𝜌𝑔𝑟 Determination Methods Capillary Rise Method Where:
h = the height the liquid is lifted,
la = the liquid-air surface tension (J/m² or N/m)
θ = contact angle
ρ = density of liquid (kg/m3)
g = acceleration due to gravity (m/s²)
r = radius of tube (m)

19. The Ring Method
where  = constant
(Du Noűy Tensiometer)

20. Principle of du Noűy Ring methods
A detecting platinum ring is hanged on the balance and the ring bottom is touched to the liquid surface
Same system can be used for plate and ring in common
Surface tension of liquid does not work along the ring bottom at this condition. Than, let the liquid surface down to detach it from the ring
The peak downward force detected by the balance before detaching the ring from the liquid surface is converted to surface tension.

21. mg = 3a cos() Pendant Drop Method
 is the surface tension of liquid
 is the contact angle at which a liquid/vapor interface meets the solid surface.
Contact Angle Goniometer.

22. Pendant Drop Method

23. Surface Tension (mNm-1) of some liquids
0oC oC 40oC 60oC 80oC 100oC
H2O
Ethanol
Acetone
Toluene
Benzene
Hg (0oC) Ag (970oC) 800
NaCl (1080oC) AgCl (452oC) 125
Intermolecular forces

24. Surface Tension
Directly depends on intermolecular forces in the solution
Inversely depends on temperature
 of metallic liquid > ionic liquid > covalent liquid

25. ls = la cosθ Liquid in The Vertical tube
ls = liquid-solid surface tension
la = liquid-air surface tension
= contact angle
Concave
Concave Adhesive>>Cohesive
Convex Adhesive<<Cohesive
Convex

26. Interface Tension and Sprading

27. Spreading Coefficient, S in Water at 20 °C
liquid B
n-hexadecane ( ) = Drop on water surface
n-octane ( ) = Spreading
n-octanol ( ) = Spreading against inpurity

28. Use the following data of
the surface/interface tensions (mN m-1) at 20oC
A B A B AB
H2O C6H
H2O CCl
H2O Hg
H2O C8H15OH
predicts the spreading behavior of B on A

29. Surface Tension of Solution
Substances in solution :
Surface active agent “Surfactant” (<o)
hydrophilic part
hydrophobic part
Surface inactive agent (>o) such as ionic compounds, acids, bases etc.

30. Surface Tension of Some Alcohols in Water at 20 °C

31. Surfactants in Solution
Micelle formation
when C > CMC

32. CMC determination
CMC = critical micelle concentration

33. Surface tension in Surfactant
Surfactants have characteristics to change surface tension over time and the curves very depended on surfactant concentration
Surfactants have a point of critical comcentration the surface tension does not get lower. That point is called “CMC”
In the lower concentration than CMC, the surface tension will change untill equilibration

34. Effect of Concentration on surface tension
Adsorption On
surface
Gibbs isotherm
 is known as surface concentration (mol/m2)
C is the concentration of the substance in
the bulk solution.
R is the gas constant
T the temperature

35. Tugas
Mencari Jurnal tentang Surface Chemistry in Important Technologies dalam web EBSCO.
2. Membuat rangkuman dalam 1 halaman A4
Dikumpulkan Kamis 7 April 2016.