CombustorCombustion Chemistry / Exothermic Release

Combustor destroys nothing. Every atom that goes in comes out, rearranged.

The first formula on this page is methane burning: one molecule of natural gas and two of oxygen become one of carbon dioxide and two of water. The atoms match on each side; only the bonding changes. The products hold their atoms more tightly than the reactants did, and the difference leaves as heat: 890.7 kilojoules for every mole of methane, about 16 grams, under standard conditions, as tabulated by NIST. That is about 55 megajoules per kilogram of fuel, or a little over 9 electronvolts per molecule.

A common mistake is to say the energy is stored in the fuel's bonds and released when they break. Breaking a bond always costs energy. The payoff arrives when the new, stronger bonds of carbon dioxide and water form. This is chemistry: electrons rearranging, a few electronvolts at a time. Nuclear fusion, which powers the stars, rearranges nuclei instead and releases millions of electronvolts per reaction. Stars do not burn.

Yet methane and air can sit mixed in a room without reacting. That is the second formula, the Arrhenius rate law. A reaction must first get over an energy hump, the activation energy, and the share of collisions energetic enough to do it is set by the exponential. Cold, almost none make it. Add a spark and the local temperature soars; the heat released then lifts the next layer of gas over the hump, and the next. That self-sustaining loop is a flame.

One more number. By E = mc², the heat from burning one mole of methane corresponds to about 10 nanograms of mass. The products of 80 grams of reactants weigh that much less, invisible to any ordinary balance.

Combustor keeps every atom. Only the arrangement changes.