While having a discussion with a friend the idea of fire being the fourth state of matter came up, in other words, a hot enough fire or "flame" can be considered plasma being the fourth state of matter. My response to this was, "No, fire or a "flame" is always in the gas phase, fire is the rapid oxidization of gases with oxygen which emits light and heat while plasma is a superheated gas which has it's conduction band electrons removed do to high temperatures. Plasma itself isn't exothermic like a flame and will not oxidize with oxygen." Then he showed me this link: http://chemistry.about.com/mbiopage.htm [Broken] Written by: Anne Helmenstine, Ph.D. This seems very wrong to me. If by some chance a flame is hot enough that its outer electrons are removed, then how can it react with oxygen and therefore produce more heat? Don't most reactions have a limiting maximum temperature at which they can occur? For a simple example, burning H2 in an O2 atmosphere. 2H2 + O2 -> 2H2O @ ~560C but.... 2H2O -> 2H2 + O2 @ +2000 °C What gives?