Interfacial Phenomena

Question 1

What is surface tension?

Answer 1

A force that pulls the molecules of the interface together and, as a result, contracts the surface

Question 2

What are the units of surface tension?

Answer 2

Dynes/ cm
N/m

Question 3

What is interfacial tension?

Answer 3

The force per unit length existing at the interface between two immiscible liquid phases

Question 4

What are micelles?

Answer 4

Aggregates which may contain 50 or more monomers

Question 5

What are the structures of micelles?

Answer 5

Spherical or cylindrical

Question 6

What is adsorption?

Answer 6

When the added molecules are partitioned in favor of the interface

Question 7

What are the applications of adsorption

Answer 7

Removal of objectionable odors from rooms and for
Operation of gas masks
Decolorizing solutions
Detergency and wetting

Question 8

Define adsorbent

Answer 8

The material used to absorb the gas

Question 9

Define adsorbate

Answer 9

The substance being adsorbed

Question 10

The degree of adsorption of a gas by a solid depends on what?

Answer 10

1. The chemical nature of the adsorbent and the adsorbate
2. Surface area of the adsorbent
3. Partial pressure of the adsorbed gas

Question 11

The types of adsorption are generally recognized as what?

Answer 11

Physical or van der Waals forces

Question 12

What is desorption?

Answer 12

The removal of the adsorbate from the adsorbent

Question 13

Which adsorption is reversible?

Answer 13

Physical

Question 14

What is a wetting agent?

Answer 14

A surfactant that, when dissolved in water, lowers the advancing contact angle, aids in displacing an air phase at the surface, and replaces it with a liquid phase

Question 15

What is an application of wetting agent?

Answer 15

Displacement of air from the surface of powders for the purpose of dispensing these drugs in liquid vehicle

Question 16

What is the most important action of wetting agent ?

Answer 16

To lower the contact angle between the surface and the wetting liquid