Could "fire" exist on a planet that has no oxygen in its atmosphere? If it was using some other chemical as fuel, how would that effect its physical properties, color/appearance, temperature, etc.? And what sort of atmospheres could support such chemical reactions?
2$\begingroup$ Ever dropped burning magnesium in water or CO2? There are many thousands of such possible reactions, but this seems to be a request for an unconstrained list - those are off-topic here. Can you edit to narrow it down to something answerable by the standards you'll find in the How to Ask section of the help center, please also take our tour for good measure, and add some specific worldbuilding context. $\endgroup$– Angry MuppetMar 17 at 23:42
$\begingroup$ Sand, glass, and even water will burn with a bright flame in fluorine gas. For example. $\endgroup$– AlexPMar 18 at 2:06
$\begingroup$ Further reading: worldbuilding.stackexchange.com/a/80478/51094 $\endgroup$– CadenceMar 18 at 3:03
$\begingroup$ Hello @SaturnianThunderDragon, welcome to Worldbuilding. This question has a number of problems, which a careful reading of our tour and these two pages, help center and help center, will explain. But if you roll your mouse over the down vote arrow, you'll learn that you're expected to perform basic research before asking your question. A simple Google search for "Oxidizers other than oxygen" includes this article: Can Fire Burn When There’s No Oxygen?, which answers your question. $\endgroup$– JBHMar 18 at 3:21
Oxygen has no unique properties when it comes to conventional fuels. Oxygen is used because it is so reactive (no gimmicks needed to make it react) and it is so abundant on this planet (easy to obtain). The point of this kind of fuel is to generate lot of heat, and there are many alternatives to oxygen.
See eg: https://www.scienceabc.com/nature/can-fire-occur-non-oxygenated-reaction.html
I think there's a frame issue here.
Fire, definitionally, is an oxidization reaction and requires Oxygen.
However, there are plenty of Extremely Exothermic reactions that one could substitute with.
Based on the article from Jani, there are non-oxygen oxidizing agents that would be possible candidates.
Just not sure if they would be considered 'Fire'.
1$\begingroup$ Oxidation reactions do not require oxygen, at least not in any kind of chemistry which is less than 200 years old. For example, both fluorine and chlorine are oxidizing agents; and fluorine is a stronger oxidizing agent than oxygen. $\endgroup$– AlexPMar 18 at 2:52
3$\begingroup$ I have seen a jet of chlorine burning in a hydrogen atmosphere. It looks like fire. I am no sure by what 'definition' it is not fire. $\endgroup$ Mar 18 at 7:16
$\begingroup$ Wouldn't fire be any sustained exothermic gas-solid aerosol phase reaction? $\endgroup$ Mar 19 at 5:13
$\begingroup$ "Fire, definitionally, is an oxidization reaction and requires Oxygen." Wikipedia has this to say: "Oxidation originally implied a reaction with oxygen to form an oxide. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions. Ultimately, the meaning was generalized to include all processes involving the loss of electrons or the increase in the oxidation state of a chemical species" from here. $\endgroup$– VLAZMar 20 at 16:59