Toni L7

Question 1

What are colloids

Answer 1

Small particles or droplets of one phase dispersed in another, bulk phase (solvent)

Question 2

What do the properties of colloids depend on

Answer 2

Their properties are strongly dependent on the interface between the particles and the bulk phase because the area of this interface is large

Question 3

What are the difference types of colloid

Answer 3

Solid particles dispersed in liquids or in solid.
Liquid droplets dispersed in liquids
Liquid droplets/ solid particles dispersed in gases

Question 4

Describe the energy increase when a bulk phase is divided into smaller parts

Answer 4

Surface tension is positive under normal circumstances, therefore there is a free energy increase when a bulk phase is divided into smaller parts

Question 5

Describe the thermodynamic tendency for small particles

Answer 5

There is a thermodynamically tendency for the smaller particles to coalesce into larger particles

Question 6

What is Ostwald ripening

Answer 6

If the particles are slightly soluble, there will be a tendency for the smaller ones to dissolve and re precipitate on the larger ones

Question 7

How do we classify colloids

Answer 7

Lyophobic
Lyophilic

Question 8

What is lyophobic

Answer 8

Solvent hating

Question 9

What is lyophilic

Answer 9

Solvent loving

Question 10

Describe the stability of colloids

Answer 10

Thermodynamically colloids are unstable with respect to the bulk material. Thermodynamic only indicates the direction in which the reaction has a tendency to go. Kinetically colloids may be stable for long periods of time