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I have a quick question about the reaction of magnesium and heat. What type of reaction exactly is produced? I thought at first it would be a combustion reaction, however carbon dioxide is not one of the products.
Question Date: 2017-03-24
Answer 1:

Note that combustion is a reaction between a fuel and an oxidant (usually oxygen). So if we have a combustion reaction involving magnesium, it would involve magnesium and oxygen as reactants and magnesium oxide (MgO) as a product--no carbon dioxide produced!

You might want to double check what the reactants are in your situation. Magnesium cannot react by itself (even with heat). To react, it needs another chemical, such as oxygen from the air or water. Without more information, I cannot be sure that you are looking at the combustion reaction--it might be a reaction with water or even with carbon dioxide as a reactant!

Answer 2:

2 Mg + O 2 -> 2 Mg 0

It's called an oxidation reaction, because the magnesium is being oxidized as it is going from its metallic form to becoming the cation in a salt, magnesium oxide.

Combustion reactions are a type of oxidation reaction, but specifically oxidation of carbon: if there is no carbon, then oxygen cannot combine with it to become carbon dioxide. Oxygen is, however, very reactive, and there are quite a lot of materials that will burn in the presence of oxygen if you get them hot enough. Even nitrogen in the air will burn to create nitrous oxides at high enough temperatures. In fact, oxygen will burn with itself to create ozone, which is why ozone is a common smell in the aftermath of a lightning strike, since lightning is one of the few Earthly phenomena that is hot enough.

Good question - channeling existing notions like this is how we do science!

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