Chapter U2.19, Problem 3E

Interpretation Introduction

Interpretation : Whether the given substances would have smell or not is to be predicted and explained.

Concept Introduction :

Humans are able to smell different molecules. Some molecules that humans are able to smell are small and polar in nature. Some medium sized non-polar molecules also have smell. Mostly humans are able to smell molecules that exist as gases at room temperatures.

Answer to Problem 3E

Decanol, C₁₀H₂₂O- Yes, one can smell it.

Lead, Pb- No, one cannot smell it.

Iron oxide, Fe₂O₃- No, one cannot smell it.

Potassium chloride, KCl- No, one cannot smell it.

Explanation of Solution

Decanol, C₁₀H₂₂O- Yes, one can smell it. Decanol is a polar molecule as it has asymmetric shape. It is also a 10 carbon compound so the size of the molecule is neither too small nor too large. The molecules having 5 to 19 carbon atoms will smell irrespective of whether they are polar or nonpolar because they occur as liquid but they are volatile in nature; that is they can easily enter gas phase. Gases can be easily detected by the receptor sites of our nose or one can easily smell gases. It also consists of only nonmetal atoms, so it is a molecular covalent substance.

Lead, Pb- No, one cannot smell it. Lead has metallic bonding and so it occurs in solid state at room temperature. It cannot be detected by the receptor sites.

Iron oxide, Fe₂O₃- No, one cannot smell it because it is a solid ionic molecule. It cannot exist as a gas and so cannot be detected by the receptor sites.

Potassium chloride, KCl- No, one cannot smell it because it is an ionic solid molecule as it contains both metal and nonmetal. It does not exist in a gas form.

Conclusion

Only decanol has a smell as it is made of nonmetals and is polar in nature. It can be easily recognized by the receptor sites of our nose.