# how does incomplete combustion of methane produce soot?

Ususally the incomplete combustion is formed this way: hydrocarbon + oxygen-> carbon + carbon monoxide + water.

• Methane is no different from other hydrocarbons in this respect. – Ivan Neretin Jun 14 '16 at 8:32

The incomplete combustion of methane can result in a slew of partially oxidized products, including $\ce{CO}$, but also methanol, formic acid, formaldehyde, and higher hydrocarbons also.

However,the oxidation of methane to soot is generally given as the following:

$$\ce{CH4(g) + O2(g) → C(s) + 2H2O(g)}$$

• fascinating! Is there a source for the first sentence? – pentane Sep 30 '19 at 1:06

It is not necessary that every hydrocarbon's incomplete combustion produces carbon. Methane has a high calorific value, so there are less chances that it will undergo incomplete combustion. Even if it goes,it will follow the reaction
2CH4 + 3O2 ----> 2CO + 4H2O

• True, methane produces less soot than other hydrocarbons; I attribute this to the absence of $\ce{C-C}$ bonds in it. Calorific value has little to do with completeness of combustion. Your reaction is of course possible, but what if we just don't have enough oxygen even for that? – Ivan Neretin Jun 14 '16 at 12:50
• Calorific value has a role in completeness of reaction. As if there was limited amount of air and there was also a substance with low calorific value, Methane would burn faster than that, therefore reducing the amount of O2 left for that other substance. And actually, we see these reactions at macro level. A reaction is never completed (in real world). We consider it to be completed as the reactant unreacted is very negligible. And so O2 would be available for combustion. – Ava Jun 15 '16 at 10:16
• OK, but what if we just mix methane with oxygen, 1 to 1, no other substances? – Ivan Neretin Jun 15 '16 at 10:25