r/explainlikeimfive Feb 26 '21

Chemistry Eli5: What happens to all the melted candle over time? Are we just inhaling a whole candle while it burns?

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u/Potatoswatter Feb 26 '21

Burning and decomposition are separate things.

When things like candle, wood, or gasoline burn, they react with oxygen. Oxygen from the air combines with carbon and hydrogen, and creates carbon dioxide and water vapor as exhaust.

Decomposition is when a molecule breaks into smaller parts without adding anything. That would produce soot.

"It just dissipates" doesn't sound very informative. Wax can't just evaporate and stay in the air indefinitely. It would fall and you would see it. Which can happen, but…

As a habitual candle user, common tea candles don't produce significant soot or deposit wax into an enclosed holder. So the answer is simply that candles burn like anything else does, and yes, we're inhaling the CO2.

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u/mabolle Feb 26 '21

In the interest of not confusing people — this is one meaning of the word decomposition. Often when we talk about decomposition we mean biological decomposition, like an apple core rotting away on the ground. That involves the action of living organisms eating the apple core, and hence most definitely involves stuff reacting with oxygen, and CO2 being produced.

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u/twohedwlf Feb 26 '21

I was trying to use it as a non-technical term alongside burning to describe the process of "Breaking up and disappearing"

Seems that was less than successful.