Chapter U2.40, Problem 2E

Interpretation Introduction

Interpretation : One piece of chemical information that is needed in predicting the smell of a compound is to be explained.

Concept Introduction :

Molecules smell differently. The chemistry behind smell is very complicated. There are many ways by which one can predict the smell of a compound. These are molecular formula, functional group, chemical name and overall shape of the molecule.

Answer to Problem 2E

The most important chemical information that helps in predicting smell is the overall shape of the molecule which can be revealed by the three dimensional structure of the molecule. It can predict camphor, minty and sweet smells.

Explanation of Solution

There are many evidences that can help in predicting smell. These are molecular formula, functional group, chemical name and overall shape of the molecule.

Molecular formula- This is helpful in predicting fishy smell which is due to presence of N atom in the molecules. It does not help in distinguishing sweet, putrid, minty and camphor smells as all these smells are shown by functional groups containing O atoms only the arrangement is different.

Functional group- This can help in predicting sweet and putrid smells but it cannot help in identifying minty or camphor smells. It cannot help in predicting smells for alcohols and ketones.

Chemical name- This is also not very useful as chemical names are based on functional groups. So, it also cannot help in predicting smells for alcohols and ketones.

Since, it is noticed that molecules with same functional groups can have different smells thus the most important information that helps in predicting smell is the overall shape of the molecule in three dimensions. The ball-and-stick model is used to represent the three dimensional view of a molecule. From this model, the arrangement of different atoms in the molecule can be seen.

Conclusion

Although all chemical information is valuable at different times in predicting different kind of smell, theshape of the molecule helps in predicting the smell of the molecule more accurately.