Why does a candle not create smoke when burning but lots of smoke when you blow it out?
In: Chemistry
The super ELI5 answer is that when a candle is burning properly, almost all of the wax is converted into gases you can’t see. When a candle is smouldering it produces tiny particles of hot soot which you see as smoke.
The more complete and slightly non-ELI5 answer is that a candle is comprised of wax which is a hydrocarbon (i.e. comprised of molecules consisting primarily of hydrogen and carbon).
When a candle is burning properly, almost all the hydrogen and carbon is combined with oxygen and converted into gases – basically water vapour (H20) and carbon dioxide (C02).
When a candle is smouldering, just after you blow it out, it can still be producing sufficient heat to split the hydrocarbons into hydrogen and carbon but not sufficient heat for proper combustion. Particles of carbon on their own are “soot” and smoke is effectively a stream of hot soot particles.
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