Question

What is meant by abnormal molecular mass? Illustrate it with an example.

Answer 1

When the experimentally observed molecular mass of a substance determined on the basis of a colligative property is found to be different from the normal value as expected from its chemical formula, the observed molecular mass is referred to as abnormal molecular mass.

Example of association: Acetic acid in benzene shows abnormally high molecular mass.

Example of dissociation: NaCl in water shows abnormally low molecular mass.