Why are some substances odorless and tasteless?
In: Chemistry
Taste and smell are sensed by nerves called chemoreceptors, which detect chemical properties of the compounds that enter the nose and mouth. For instance, the sour receptor reacts to low pH values of acids, bitter receptors react to chemicals called alkaloids, and sweet receptors react to chemical structures found in sugars (not sugars themselves, which is why artificial sweeteners work). If a chemical does not trigger any of these receptors it has no sourness, no bitterness, and no sweetness. Water does not trigger any of them because it has a neutral pH and doesn’t have the chemical structures to trigger the other two. So, water has no taste, but the things dissolved in it might.
From an evolutionary perspective, senses evolved to help us move toward things that are good for us and away from things that are bad. If a chemical is neither good nor bad, like the nitrogen that is 70% of the atmosphere, there’s no reason for us to notice it.
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