| MadSci Network: Chemistry |
Any time you see a flame, you are witnessing a highly exergonic reaction - namely one that releases a lot of energy. The opposite of of an exergonic reaction is an endergonic reaction, or one that requires the input of energy for it to go forward. A simple example of an exergonic reaction is letting your bike roll down a hill - it proceeds 'instantaneously,' and releases energy in the form of motion, sound, and heat. Pushing your bike up the hill would be an example of an endergonic reaction - it won't go by itself; you have to push it.
When exergonic reactions release energy, much of it is in the form of heat, or energy that transfers to surrounding atoms, causing them to vibrate and move faster. Since fires release so much energy, much of it is transferred to the surrounding atoms and molecules as heat.
The color of a flame depends on many factors. Not all flames are orange or red. Methane gas produces a blue color. If you place a piece of copper wire in an open flame you will see streaks of green caused by excited copper atoms released into the flame. Sodium (as in the sodium in table salt - sodium chloride) produces a yellow color.
-Nick