Chapter U2.9, Problem 2E

Interpretation Introduction

Interpretation:

Theory behind the three alcohols smelling differently even though they have the same functional group is to be explained.

Concept introduction:

Molecules are three dimensional. A ball and stick model helps us in knowing the exact arrangement of atoms in space. Each molecule has a different shape. Even if the molecules have same functional groups; they may smell differently.

Answer to Problem 2E

The three alcohols smell different even though they have the same functional group(-OH) because they have different three dimensional shapes. The three alcohols are geraniol, menthol and fenchol. They differ in their shapes and hence differ in smell. In geraniol, the carbon atoms are connected in long chain whereas menthol and fenchol have ring structures.

Explanation of Solution

The three alcohols have different smell because their overall shapes are different. The ball and stick model tells us about the overall shape of the molecule. Molecules with same functional groups, such as geraniol C₁₀H₁₈O, menthol C₁₀H₂₀O and fencholC₁₀H₁₈O differ in their overall shapes. Hence they differ in smell. In geraniol, the carbon atoms are connected in long chain whereas menthol and fenchol have ring structures.

Conclusion

The structural formula of a molecule shows the molecule flat with the carbon atoms arranged in line whereas the ball and stick model shows the three dimensional structure of the molecule. This helps in better understanding the shape of the molecule. Differently shaped molecules have different smell even if they have the same functional groups.