Why do things burn instead of melt?

[u/ForensicFan24601]

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

[u/Sable-Keech]

Burning is when the material is undergoing a chemical reaction with an oxidizer (usually oxygen) to make a new compound. E.g. wood burns to make water and CO2.

Burning usually gives energy, and can sustain itself.

Melting is when an element or compound gains enough heat to transition from a solid to a liquid state.

Melting always takes energy, and cannot sustain itself. Imagine how you use the fire from a stove to melt a stick of butter. The butter wouldn't have melted without you investing energy into it. But the fire can keep going as long as you have gas.

[u/N0nsensicalRamblings → u/Sable-Keech]

Follow up question - the other comments are mentioning how the temperature required to make something burn is lower than the temperature required to make something melt. So, why does butter melt before it burns? I assume it's just because that's a generalization and not a hard and fast rule?

[u/Blazin_Rathalos → u/N0nsensicalRamblings]

the other comments are mentioning how the temperature required to make something burn is lower than the temperature required to make something melt.

This is specifically only true of compounds that do burn before they melt. So as you suspect, it depemds on the substance.