# Mass converted to energy in a common fire?

In a common wood fire such as a campfire, is matter converted to energy or is it simply an exothermic chemical reaction and all the mass can be accounted for in the ash and soot?

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Note: Post-reaction mass is accounted for in the wood, soot, AND the CO2 and H2O that comes from the reaction. Even if you collected 100% of the solid matter after a fire, the mass will be much less due to what's lost as a gas. –  Alan Rominger Oct 30 '11 at 3:52

In a chemical reaction you have a set of reactants and a set of products. If you were to take the mass of the reactants and sum them up, you would find them to be more than the sum of the mass of the products. This mass difference time $c^2$ is the energy of the reaction. Again, this is by an amount that is so small that it is unmeasurable. The mass change from of nuclear reactor fuel after burning it at a large heat rate for 4 years is barely measurable itself, if you're talking about putting the fuel on a scale and measuring it.