|MadSci Network: Chemistry|
When sodium and chloride ion dissociate in water, they don't actually go rocketing off in opposite directions. Rather, they stay 'associated' with one another, held within a given proximity by their respective electro-negativities. A change in pH will cause that proximal distance to change, and thus, a change in taste. For instance, salt water tastes very much like salt, but salt disolved in something acidic such as lime juice will have a very different taste. Our taste buds are designed to be stimulated 'from both ends' simultaneously by both the sodium and the chloride ion. If the ions don't separate, on the other hand, they can (as salt crystals) have no flavor since the valence electron orbitals are completely associated together in the ionic pairing (bond) and will have no interaction with your taste buds. I don't know what either sodium or chlorine tastes like, but obviously not like salt. The taste bud has to get it from both ions at the same time in order to register as 'salt.'
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