In this assignment, you will write and balance a chemical equation. Then, you will use a table of enthalpy values to calculate the energy change in the reaction. Next, you will create a model of the energy change
in the reaction. Finally, you will write an explanation that describes the energy change in the reaction.
Background Information
Chemical bonds contain potential energy. The breaking and forming of bonds that occurs during a
chemical reaction results in the release or absorption of energy. Chemical reactions that release energy
into the surrounding environment are called exothermic reactions, while chemical reactions that absorb
energy from the surrounding environment are called endothermic reactions. Since energy is conserved
during chemical reactions, the total amount of energy in the reaction and the surrounding environment
remains the same.
During a chemical reaction, bonds in the reactants are broken and new bonds are formed in the products.
Energy is needed to break the bonds in the reactants, so breaking bonds is an endothermic process.
Forming new bonds, on the other hand, is an exothermic process because energy is released when new
bonds are formed in the products. A chemical reaction is an exothermic reaction if more energy is
released when new bonds are formed in the products than is used to break the bonds in the reactants
Conversely, if more energy is used to break the bonds in the reactants than is released when new bonds
are formed in the products, the chemical reaction is an endothermic reaction
The amount of energy change in a reaction can be determined by calculating the enthalpy of reaction
(AH). If the enthalpy of reaction is negative, then the reaction is exothermic If the enthalpy of reactions