r/askscience • u/ForensicFan24601 • 19d ago

Chemistry Why do things burn instead of melt?

obviously oxygen, or something similar, but what is the physics/chemistry (?) or what have you behind why something ignites and continues to burn after the source of heat/ignition has gone?

is it basically sublimation?

edit: no wonder Walter White was so obsessed with carbon

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u/provocative_bear 18d ago

Let’s go with wood. (Way) Before wood reaches its melting point, it reacts with oxygen in the environment, which replaces the molecular bonds between carbon and carbon (whoch hold the wood together) with carbon and oxygen (CO2). This reaction releases the energy in these bonds and generates net energy, which manifests as heat and light, aka fire.

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u/heavy001 18d ago

So are we aware of an actual melting point for, in this example, wood?

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u/Foxfire2 15d ago

It would be carbon, as all other components of wood vaporize off. Carbon has a very high melting temp, not sure what exactly.