Classify colloids where the dispersion medium is water, State their characteristics
and write an example of each of these classes.
Colloids are classified into two types in the cases where dispersion
medium in water. They are:
(i) Hydrophilic or Lyophilic colloids: Those substances, which when mixed with
the dispersion medium, form directly the colloidal solution and are termed as
hydrophilic colloids. They are reversible solutions, quite stable and cannot be
Example: gum, gelatine, starch, rubber etc.
(ii) Hydrophobic or Lyophobic colloids: Those substances which do not form
colloidal solution when simply mixed with the dispersion medium, are called
hydrophobic colloids. They are irreversible solutions, unstable and can be
Example: Metals and their sulphides