12. Heat, Energy, and Chemical        Bonds   Previous PageNext Page
       Fuels, Combustion, and Energy

We can use the spring analogy below to illustrate why combustions in strongly electronegative media are exothermic, or heat-emitting. Let the ball in the middle symbolize the electrons, drawn either toward oxygen at the left, or carbon and hydrogen at the right. The stronger spring to the left represents the greater electronegativity of oxygen, and the weak spring at the right, the lesser electronegativities of carbon and hydrogen.


If water and CO2 were to react to form methane and O2, electrons would be moved away from oxygen, against oxygen's natural electronegativity. This corresponds to using energy to push the ball to the right, thereby stretching the strong spring. This energy is stored in the spring (or in the methane molecules) as potential, or latent, energy.

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