Zippiot wrote: soot burns because it isnt pure carbon. things that burn are part hydrogen, hydrocarbons burn. if you remove the hydro part there is nothing flammable left. think about the best things to burn: gasoline (hydrocarbon) alcohol (hydrocarbon). now think about things that burn "pure": hydrogen. carbon is the unburnable part that is left behind after a reaction, if there isnt anything except hydrogen all that comes out of the reaction is water.
your wrong, for example; metals burn, try lightening steel wool no hydrogen involved.
You only get soot because there is a to low temperature and/or to les oxygen.
The thing whatâ€™s leftover if you burn something is ashes. Which are mostly oxides and salts who were already present or formed in the burning process.