Interfacial Phenomenon

Question 1

What is interfacial phenomenon?

Answer 1

the behavior of molecules at the boundaries of phases (interface)

Question 2

Are intermolecular forces attractive or repulsive?

Answer 2

BOTH

Question 3

How many interphases are there and what are they?

Answer 3

There are 6: 
S-S
S-L
S-G
L-L
L-G
G-G

Question 4

What is the boundary between the interphase called?

Answer 4

interfacial tension

Question 5

When a phase in the interphase is gas, what can interfacial tension be called?

Answer 5

surface tension

Question 6

What does surfactants do?

Answer 6

lower interfacial tension between ingredients; lower contact angles

Question 7

γ

Answer 7

surface tension

Question 8

What is temperature’s effect on surface tension?

Answer 8

surface tension decreases with increasing temperature; you must report a temperature value when giving surface tension value

Question 9

What is a tensiometer?

Answer 9

a device used to measure interfacial tension

Question 10

What are the different methods used to measure interfacial tension?

Answer 10

• Du Nouy Ring method
• Capillary Rise method
• Wilhemy plate method

Question 11

Du Nouy Ring method equation

Answer 11

γ = k x F

Question 12

Capillary Rise method equation

Answer 12

γ = (h r d g) / (2 cos θ)

Question 13

Wilhemy plate method equation

Answer 13

F = 2(L + T)γ cos θ
γ = F / (2 x F)