Answer: The changes in energy that occur during a chemical reaction can be seen by examining the changes in chemical bonding. This can be used to classify reactions as exothermic or endothermic.
Step-by-step explanation:
Energy changes Breaking and making bonds during a chemical reaction bonds in the reactants are broken new bonds are made in the products energy is absorbed to break bonds. Bond-breaking is an endothermic process. Energy is released when new bonds form.