Question about exothermic and endothermic reactions?

Question

Suppose you have to burn a piece of charcoal.
During combustion of the charcoal heat energy is released, so it is exothermic reaction, but heat is required to start the whole burning process! When we ignite the fuel we need to light a march first, which first gives some heat energy to the charcoal before the charcoal starts reacting with oxygen in the air. But on thw whole, the heat energy released during burning is much more than that required to start the reaction, so it is exothermic?

So at the beginning the burning of charcoal is an endothermic reaction, and after that it becomes exothermic? Can we separate combustion into 2 stages? Thanks!

Answer 1

It describes the reaction so I would say it is solely exothermic, because the reaction is to give off energy.

Answer 2

The chemical reaction during the process you gave is actually the combustion of charcoal, wherein it is already "burning" or "ignited". In this case, energy is released, therefore it is exothermic.

The preparatory process is endothermic, because you need to reach the "kindling point" of the fuel before combustion occurs. However, you cannot use this to tell that the whole reaction (combustion of coal) is endothermic, because it is nonspontaneous. You really need to heat it before it even gives heat.

Bottomline: The main process is merely exothermic, and the preparatory process is endothermic

Answer 3

I am not speaking from my own expertise but from a website which says: "Strike a portable chemical reaction stick (strike-anywhere match) and note heat caused by the friction of the match against a surface causes the match to ignite. Also note that heat and light are released via the flame. Explain that the release of heat in a chemical reaction (or physical change) that exceeds the amount of heat used to start the reaction is an exothermic reaction."

So it looks like you are considering the net energy change, and the process is exothermic.

Answer 4

Exothermic: the reaction consumes a little energy, then it creates heat and releases that heat into the environment (more heat than it used up). Endothermic: it takes more heat to start the reaction than heat produced.

Answer 5

I think since you're refering to the reaction itself, it's strictly an exothermic reaction. The heat put intto the reaction to start it, only started it. The reaction of charcoal burning did not begin until it got hot enough.

Answer 6

<>Exo- and endo-thermic are net energy equations. If the energy given off surpasses the energy taken in, the reaction is exothermic, and vice versa.