Question

Comment on the statement that ‘Colloid is not a substance but a state of substance.

Answer 1

Hint: Before answering the question, we should know what is colloidal. The mixtures in which microscopically dispersed insoluble particles of one substance are suspended in another substance are known as Colloids (also called as colloidal solutions or colloidal systems). If a mixture has to be classified as a colloid, its suspended particles must not settle.

Complete answer:
Tyndall effect (It is a phenomenon in which beams of light incidents on colloids are scattered due to the interactions between the light and the colloidal particles) is exhibited by colloidal solutions.
The colloidal state is the state of subdivision in which molecules or poly molecular particles having at least one dimension in the range of 1 nanometre and 1 micrometre, are dispersed in some medium. Colloids generally feature substances evenly dispersed in another. In such mixtures, the substance which is dispersed is referred to as the dispersed phase whereas the substance through which it is dispersed is called the continuous phase.
The statement, ‘Colloid is not a substance but a state of substance’ is rightly said. It is because the same substance, under different conditions, may exist as a crystalloid or as a colloid.
For instance, NaCl in water acts as a crystalloid whereas in benzene, it behaves as a colloid. Dilute soap solution acts as a crystalloid whereas concentrated solution acts as a colloid. The size of the particles decides the state of the substance. If the particle-size lies in the range 1-1000nm, the particles are in the colloidal state.

Note:
Application of Colloids:
It is widely used in industries, medical and domestic applications.
It is used as food items.
It is used in medicine.
It is used in the purification of air by Cottrell precipitator.
It is used in tanning of leather.
It is used in the formation of delta.