There are enzymes in your mouth that help speed up the procees of digestion. Energy and chemical reactions Chemical reactions require energy. This energy can either be released or absorbed. Chemical reactions that give up heat energy are called exothermic reactions. Burning wood in a fireplace gives off heat to warm you up.
Most chemical reactions are exothermic.
Endothermic reactions absorb heat. Baking powder in dough causes bread to rise. It absorbs the heat from the oven to form carbon dioxide gas. Chapter 4- Measuring Energy Pages and gif animations written and designed by Sheila M. Estacio.