system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why does a marshmallow, when burned completely, leave hard black charred material behind? Is that made up of carbon?

Is the process incomplete combustion or just caramelization gone too far?
gpt
Marshmellows are essentially pure sugar. Sugar is made of of three elements:

Carbom

Hydrogen

Oxygen

The products of said reaction, given perfect quantities of all elements, are CO2 and H2O.

That said, the reactions are not perfect, and there is more carbon left over at the end. It remains in an elemental state, being solid Carbon (black char) that you see.