Chapter U2.18, Problem 2E

Interpretation Introduction

Interpretation:

One theory must be described to show non-polar small molecules donot have a smell.

Concept introduction:

A compound has smell if the molecule can bind with nasal receptor and a nerve impulse reaches brain.

Answer to Problem 2E

Polarity plays an important role in smell of a molecule. Non-polar small molecules can’t bind with nasal receptor. So small non-polar molecules donot have a smell.

Explanation of Solution

One important theory to explain smell of a compound is receptor site theory. The odoring molecule and receptors must have stucture complimentary to each other for properly binding which results in the generation of nerve impulse. This is carried by olfactory nerve to brain where recognisition of the smell takes place. As small molecule which are non-polar can’t bind with nasal receptors properly, these molecles don’t have a smell.

Conclusion

Receptor site theory is used to explain why small non-polar molecules don’t have smell.