Why does a candle make no smoke when it is lit but makes a lot of smoke when you blow it out?
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The smoke which you see is paraphin or wax, it is actually a fuel of candle. When you blow candle out fuels is stoped being consumed
Do candles with that wax put off dangerous gas?
Smoke is a result of incomplete combustion. Candle flame is the result of wax melting, being drawn up through the wick, then vaporizing and combining with oxygen in the air. With enough heat and oxygen the vaporized wax will completely oxidize (combine with oxygen) and the majority of the resulting chemicals will be invisible gasses. If there’s not enough oxygen, or not enough heat, then the wax will only partially oxidize, and the wick will start to burn as well. The result of this partial combustion is smoke, a mix of a lot of different chemicals, including many heavier particles that become tiny bits of solid as they cool.
At the scientific level, a fire is a chemical reaction where some molecules (usually carbon based) are reacting with oxygen to produce energy.
The hotter the fire is, the better it reacts with the oxygen.
With really hot fires, oxygen reacts with the carbon and creates mostly carbon dioxide or CO2
When the fire gets cooler, it creates less CO2 and it creates more carbon monoxide or CO
When it gets even cooler, carbon by itself starts getting released. The carbon is a solid, not a gas, so you can see it.
When the candle is burning brightly, it’s creating mostly just CO2 and CO. When you blow it out, it keeps burning for a bit, but now it isn’t hot enough to produce the gasses, just mostly carbon.
in accordance with the other comments, go ahead and blow out a candle, and take a lighter to the smoke that rises and see the flame follow the trail of unignited wax vapor back to the wick
The fire burns the smoke. If you blow it out, it stops burning it and then you can see it.
There, like you’re five.
Wax that’s not been burned but is hot enough to vaporize is coming up. Think of a car with bad emissions
The “smoke” is the wax evaporating from the wick and condensing into tiny particles. When the candle is lit, this evaporated wax is what’s burning. The wick is mainly providing a surface for the wax to evaporate from.
‘Fire’ is more of a system than a single thing. You need fuel, heat, and oxygen, but when we think of ‘fuel’ the thing that burns isn’t actually the piece of wax or the stick of wood. It’s tiny pieces of wax or wood that have *pyrolyzed* into tiny particles that float in the air. That stream of particles is called ‘smoke’.
When you see a candle flame, the visible part you see emitting light is *not* where any burning occurs. The burning occurs on the tips and edges of the flame.
The visible flame is actually smoke – smoke heated up so much that it glows red-hot, just like metal coming out of a forge. But it doesn’t burn because there’s no oxygen inside the flame. As the smoke flows upward and outward it eventually comes into contact with oxygen. As soon as the super-hot atomized fuel touches oxygen, it burns, becoming water vapor and invisible gasses like CO2, and emitting a lot of heat. This heat is sent out in all directions, including back towards the oxygen-free bubble and towards the fuel source. This produces more smoke, and heats up that smoke so it glows red-hot, which will eventually float out to find some oxygen and do some burning of its own, perpetuating the cycle.
So to answer your question, the candle is *always* creating smoke. It’s just also heating up and burning that smoke, in order to create and heat up more smoke to burn. When you extinguish the candle, you’ve interrupted the cycle. The fuel source still has heat, and is still pyrolyzing, generating a stream of smoke until it cools down. But the smoke is no longer being heated up, so it doesn’t glow, and it doesn’t burn.
This is why the [this cool party trick](https://www.youtube.com/watch?v=cPJLw7Xkmzk) works. The candle is relit from the stream of smoke, because lighting the smoke, and lighting the candle is basically the same thing. You heat up the smoke that’s mixed in with oxygen, it burns instantly, the burning heats up more smoke/oxygen mix below it, and that combusts, heating up more below it, and it follows this cycle all the way back to the base of the candle, where it takes root heating up the fuel source to get more smoke to burn.
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