Free post: energy and chemistry

Spencer, J, Bodner, G, & Rickard, L (2008). Chemistry, Structure and Dynamics. John Wiley & Sons, Inc. (pages 260-263)

Energy is something that can't be created or destroyed. It’s said to be conserved. “Energy changes that occur during a chemical reaction are due to the making and breaking of chemical bonds.”(p.262) If you make dymethyl ether (or ethanol) out of 2 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom, then this process will give off energy because energy is always released during the formation of chemical bonds. Ethanol (CH3CH2OH gas) and dimethyl ether (CH3OCH3 gas) have different molecular formulas, but when they are burned in the presence of oxygen their products are the same. Because their formulas are different, their bonds are different too, so it takes different amount of energy to break bonds of one mole of chemical versus another. Breaking of chemical bonds always requires an input of energy. So to sum up, you put in energy when you want to break the bond between atoms, and you will release energy to make a bond.