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Is odor a chemical property?
Question Date: 2019-01-12
Answer 1:

First, some background on properties.

There are two general categories of properties that are used to describe materials: chemical properties and physical properties.

Chemical properties describe chemical changes of matter, i.e. changes that result in changes to composition of matter. Some examples are flammability, acidity, and oxidation behavior. In contrast physical properties are characteristics that can be measured without changing the chemical composition of the matter. These include mass, length/shape measurements, and phase transformation temperatures (e.g. boiling and melting points). Next, consider what "makes" an odor .

Basically, molecules of the matter in the air dissolve into mucus and eventually bind with (physically fit into) smell receptors. All of these are physical changes though; none are related to a change in composition. Thus, odor is not a chemical property, but rather is a physical property. That being said, a new odor being detected can be an indication of a chemical change which resulted in the formation of a new substance (one with a different associated odor).

[All of this is in contrast with the ScienceLine answers here, but those answers give essentially no discussion of the differences between chemical and physical properties or of odors.

These answers give more background on odors, but not chemical vs. physical properties.]


Answer 2:

When I was an undergrad, my professor got a chemical manufactured for his research. The bottle said it had 'no physiological effects,' but it smelled like popcorn. The professor said 'odor' was a physiological effect.


Answer 3:

Not really - odor is something that your senses are able to detect. Different animals smell different chemicals, and are more or less sensitive to different chemicals. What chemicals are odiferous even varies within species - what you smell may not be the same as what somebody else smells.


Answer 4:

No, odor is a physical property. In general, properties of materials are classified as chemical or physical. Physical properties are determined without changing the identity of the substance. That means that there is no change to the atomic or molecular structure of the substance. Chemical properties are the opposite - they do involve change to the molecular or atomic structure of the substance. Broadly, this means that chemical properties have to do with chemical reactions, and physical properties do not. You smell an odor when molecules of the substance enter your nose and bind with receptors (that means they fit into and then stick to the receptors, like how two Lego blocks stick together) in your nose, which then relay a message to your brain which it interprets as a “smell.”

Since we smell things without causing any change to the molecular structure of the substance, odor is classified as a physical property. Note that chemical reactions take place in our body so that the receptor can communicate with our brain, but there is no chemical reaction to the molecule of the substance itself.



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