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I'm wondering what the temperature of pure oxygen being burned is.

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closed as not a real question by Richard Terrett, F'x, ManishEarth May 23 '12 at 3:57

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

Hi Peter, welcome to Chemistry StackExchange! As you can see from the answers given below, your question not very clear and maybe there is some confusion on your hand. Maybe you could specify it further after reading the answers? Otherwise, it may be closed as too broad or ambiguous. –  F'x May 15 '12 at 9:54
If you're curious what the "hottest" fuel is, it's dicyanoacetylene (C4N2). The center of the flame at room temperature is roughly 9010 degrees Fahrenheit. –  LeakyBattery May 15 '12 at 15:39
Oxygen is not a fuel; it is an oxidant, as others have noted. However, ozone is a fuel, and ozone flames exist. –  Geoff Oxberry May 15 '12 at 18:37
There are flames burning in Chlorine, Fluorine etc. Big amounts of the chlorine from salt electrolysis is burned with hydrogen when demand for lye is bigger than for chlorine. Diborane and F2 is said to be one of the most energetic flames. –  Georg May 15 '12 at 21:57

3 Answers 3

Oxygen is not a fuel by itself, it's only the oxidant. Combustion involves a fuel (acetylene, for example) and an oxidizer (here, O2). So if you have no fuel, but all oxidizer, then what's left to burn?

Combustion is just a name we give to certain reactions. The point to get here is that the burning and its associated temperature is dependent on the reactants' chemical nature and stoichiometry. When a flame has a higher temperature than another, it means that both reactions give products that have different enthalpies of formation.

The greater the difference between the enthalpy of the products and reactants, the greater the flame temperature.

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Other answers have emphasized the fact that oxygen is not a fuel, but an oxidizing agent. I'll try to underline another point: there is no uniquely defined “combustion temperature” for a chemical compound. This is unlike phase transitions like melting and ebullition, which happen at fixed temperature for a given pressure.

The temperature of a combustion process depends on many parameters, including the heat of combustion, the ratio of air to fuel, the heat capacity of both and the initial temperature. The adiabatic flame temperature is one of such combustion temperatures under certain conditions. The autoignition temperature and flash point, on the other hand, are characteristics of a given chemical compound; they are not, however, combustion temperatures.

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I was going to mention this, but I wasn't too sure of it--lots of flames are said to burn at "xyz degrees", so I neglected to. Any idea what those temperatures are? –  ManishEarth May 15 '12 at 9:40

Pure oxygen does not burn. Oxygen is a supporter of combustion, not a combustible material(fuel) itself.

Combustion reactions are as follows:

$$\text{combustible stuff} \ce{+ O2 -> } \text{various oxides} + \text{heat}$$

Note that nitrous oxide ($\ce{N2O}$) is also a supporter of combustion, which means that you can use it to carry out a combustion reaction without oxygen--but this is only because $\ce{N2O}$ generates oxygen itself.

Since combustion is a reaction with oxygen, what's left for oxygen to oxidise? Itself? Not likely. You need a fuel to release heat for a combustion reaction.

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