eli5- what happens at the tip of a flame?

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maybe this is a silly question, but i suppose i don’t know. if you watch a candle, you’ll see the flame become needle sharp and then vanish into the air. it can be a single point, or several small ones. the candle can also relax into a blurry state where there is no sharp tip. can you explain why this happens, and if anything interesting is going on?

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Anonymous 0 Comments

The light of the candle is emitted by tiny particles of soot that glow as they burn. The tip of the flame is where they’re finally fully consumed, as they come in contact with the pure oxygen in the air. The inside of the flame has less oxygen, as it’s constantly being consumed. The clear center of the flame has no oxygen, just wax vapor.

Sometimes you can see streams of bigger soot particles that “stick out” as they take a little longer to fully burn. I think that’s from the glowing tip of the wick. When the tip is not glowing, usually because it’s fully soaked in wax, the sharp streamers disappear and the flame becomes more rounded.

If the flame is too large, you can see the soot turn black and escape from the tip of the flame. This us because pure soot doesn’t burn hot enough to support its own combustion. What you don’t see is the hydrogen from the hydrocarbon wax also burning, but it contributes enough heat that normally the soot is consumed.

I’ve been playing around with candles since I was six, under parental supervision, and my parents enjoyed candles a lot. I also enjoy chemistry and pyrotechnics, and never grew out of playing with fire like my siblings did.