Interfacial Phenomena

Question 1

What is an interface?

Answer 1

A boundary between two immiscible phases

Question 2

What happens to liquid molecules in a vapour-liquid interface?

Answer 2

Liquid molecules on the top only have cohesive forces with molecules adjacent and below, experience a net inwards force towards the bulk.

Question 3

What is surface tension?

Answer 3

The force per unit length that is applied parallel to the surface to counteract the inwards pulling force

Question 4

What are the units of surface tension?

Answer 4

Dynes per cm

Question 5

What happens at the interface of two immiscible liquids?

Answer 5

Strong forces of attraction between molecules of the same phase, weak forces between molecules of the two immiscible phases at the interface

Question 6

What is the critical micellar concentration?

Answer 6

The concentration at which the surfactants have saturated the interface and are beyond the solubility in the liquid