Can oxygen burn, or is this idea the technical equivalent of splitting an infinitive in the presence of the grammar police?

The terms “burning,” “fire” and “combustion” are synonyms with varying degrees of specificity. “Burning” is the broadest of the three, referring to phenomena ranging from the effect of capsaicin on the tongue to the fusion reactions of elements such as oxygen in stars.

The sometimes controversial discussion of what is meant by “burning” or “combustion.” is an old one. We begin by looking at an excerpt I have translated from an old chemistry text (1892), Technik der Experimentalchemie by Professor Rudolph Arendt (1892).

"Reverse flames occur when one conducts oxygen or air into a compartment which is filled with a combustible gas, and the gas mixture is ignited at the open end of the inlet tube; it has then the complete appearance as if the oxygen or air were burning. The process, however, differs from normal combustion only therein that here the combustible material is always present in excess, for which reason (when using illuminating gas) in the case of the inverse flame, light products of the incomplete combustion arise, which is, of course, impossible when hydrogen is used.

In truth, the oxygen or air in the inverse flame no more “burns” than it does normally, if one understands “combustible substances” to refer to those which can combine with oxygen. When, however, chemists quite commonly become accustomed to saying “oxygen burns in hydrogen,” this is to be understood in the above sense."

In essence, Professor Arendt made two major points:

1. The idea that oxygen “burns” in an atmosphere of fuel gas was “commonly accepted” by chemists in the 1892 era (a fact which neither proves nor disproves the issue of whether oxygen “burns.”).

2. Whether or not oxygen can validly be said to “burn” depends on how one defines combustion. If the definition of combustion is arbitrarily confined to the reactions of substances which combine with oxygen, then clearly molecular oxygen cannot burn.

Now we jump ahead 114 years to get an idea of contemporary thinking on the nature of “combustion.” For this exercise, I have selected an excerpt from professor Quintiere’s new book (2006) entitled “Fundamentals of Fire Phenomena”:

"A flame could begin with the reactants mixed (premixed) or reactants that might diffuse together (diffusion flame). Generally, a flame is thought of with the reactants in the gas phase. Variations in this viewpoint for a flame or fire process might occur and are defined in special terminology. Indeed, while flame applies to a gas phase reaction, fire, and its synonym combustion, refers to a broader class of reactions that constitute a significant energy density rate. For example, smoldering is a combustion reaction (that could occur under temperatures as low as 600 K) between oxygen in air and the surface of a solid fuel. The combustion wave propagation through dynamite might be termed by some as an explosion, yet it is governed by premixed flame theory. Indeed, fire or combustion might more broadly represent an exothermic chemical reaction that results from a runaway rate caused by temperature or catalytic effects. Note that we have avoided the often-used definition of fire as ` a chemical reaction in air giving off heat and light'. However, a flame may not always be seen; e.g. an H2 flame would be transparent to the eye and not easily seen. A flame could be made adiabatic, and therefore heat is not given off. This could occur within the uniform temperature soot-laden regions of a large fire. Moreover, oxygen in air might not be the only oxidizer in a reaction termed combustion or fire. In general, we might agree that a flame applies to gas phase combustion while fire applies to all aspects of uncontrolled combustion."

If you ask a dozen experts to define combustion and consult a dozen reference works, you may come up with 24 different answers depending on the underlying and premise in the mind of the author of the opinion. Personally, I have always taken the same view as that expressed by Professor Quintiere. Using that premise, I am sure that Professor Arendt would have agreed that oxygen can sometimes be said to burn.

Those who believe that “combustion” should be limited to reactions involving molecular oxygen, to the exclusion of, say, a fire in a chlorine plant or a dynamite explosion are certainly free say, "Oxygen can never burn" based on their premise. The technical grammar police have no authority in this long-standing discussion.