A collidal solution is biphasic and heterogeneous. It is composed of two phases : 1. Dispersed phase; 2. Dispersion medium.

Contains only water soluble particles

A colloid always :

Notes on Surface Chemistry

Concepts Used:

Surface Chemistry

The study of the chemical phenomena that occur at the interface of two surfaces which can be solid-liquid, solid-gas, solid-vacuum, liquid-gas, etc.

Read Also: Surface Chemistry

Applications of surface chemistry are:

Adsorption:

The process of attraction and aggregation of the molecules of a substance on the surface of a solid is known as adsorption. For Example, N₂ adsorbs on the surface of activated charcoal

Two types of adsorption are:-

Chemisorption: It is also known as Chemical Adsorption.
Physisorption: It is also known as Physical Adsorption.

Corrosion:

The process through which the refined metals convert themselves into more stable compounds is known as corrosion.

Crystallisation:

The type of technique used in order to purify the substances to separate Solids from liquids is known as crystallisation.

Heterogeneous Catalysis:

The process wherein a catalyst is used in order to increase the rate of a chemical reaction is known as catalysis. The catalyst does not undergo any transformation and can be recovered in a chemically unchanged state.

There are two types of catalysis:-

When the catalyst involved and the reacting substances are same states of matter or in the same phase, it is known as Homogeneous Catalysis.
When the catalyst involved and the reacting substances are in different states of matter or different phases, it is known as Heterogeneous Catalysis.