Question

The boiling point of the hydrochloric acid varies with its concentration.
a.) True
b.) False

Answer 1

Hint: The boiling point of a substance depends greatly on the forces that bind the molecules together. The concentrated solution has more number of molecules and as a result higher forces of attraction while on decreasing the concentration, the forces of attraction between molecules decrease due to increase in space between the molecules.

Complete answer:
First, let us understand what is the boiling point and on factors that depend on it.
The boiling point is defined as the point on the temperature scale at which the vapour pressure of a liquid is equal to the atmospheric pressure surrounding the liquid. It is a physical property like the density, melting point etc. The boiling point of a molecule depends upon various factors as-
- The first one is atmospheric pressure. On decrease in atmospheric pressure surrounding the liquid, the boiling point of the liquid also decreases.
- The other one is the forces of attraction between molecules. If the forces of attractions are strong and the molecule is tightly held, then it has high boiling point. On weakening of forces of attraction also, the boiling point decreases.
So, if we have a concentrated solution. It will have more number of molecules of HCl and thus they will have strong bonds between them. But on dilution, the number of molecules will decrease. The forces of attraction binding these molecules also decrease. Thus, the boiling point will also decrease with decrease in concentration.

So, the answer is true. Yes, the boiling point of hydrochloric acid varies with its concentration.

Note:
It must be noted that when we have more concentration, there are more numbers of solute. The solute molecules crowd in the solvent and as a result, solvent finds it difficult to boil. Thus, the boiling is high at high concentration.