Write an essay that explains the energy changes that occur during a chemical reaction. When is energy absorbed and when is it released? Explain what activation energy is and give some examples of sources for this energy. Explain the difference between exothermic and endothermic reactions. Give an example of each. Your essay should be at least 2 paragraphs long. Remember to write in complete sentences, using appropriate grammar, punctuation, and spelling. Be sure to cite any sources that you use.