Sciency Words: Volatile (An A to Z Challenge Post)

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, V is for:

VOLATILE

Whenever I hear somebody talk about volatile chemicals, I’m never quite sure what they mean. This is another case of a word that means one thing to the general public and something rather different to professional scientists.

In chemistry, a volatile chemical—also refered to simply as “a volatile”—is a chemical substance that tends to evaporate spontaneously under ordinary temperature/pressure conditions. A common example of a volatile here on Earth is water.

Of course you may encounter other chemicals here on Earth far more volatile than water. Just think about alcohol or gasoline. You might also think about nitrogen, oxygen, or hydrogen, because if you manage to get these chemicals into their liquid phases, they will immediately turn back into gases at the first opportunity. That makes them extremely volatile.

To be clear, the volatility of a chemical has nothing to do with how flammable, explosive, reactive, or unstable it is. That may seem a little confusing, but unlike previous confusing chemistry terms we’ve seen (like organic or reduction), I’m not sure I can fault chemists for this one. The chemistry definition is actually closer to the original meaning of the word; in a sense, it’s the rest of us who’ve been using the word wrong.

When volatile first entered the English language from French, it could mean either “light weight” or “evaporating quickly.” The “violent and unpredictable” meaning didn’t come until later. If you go further back into the word’s history, you find it derives from a Latin word meaning “to fly away,” which is actually an apt description of what atoms and molecules do when a volatile chemical evaporates.

Next time on Sciency Words: A to Z, the WIMPs will take on the MACHOs. Which acronym will win?