Your instructor will begin by modeling an endothermic chemical reaction on the board for you using a set amount of energy (potential energy + kinetic energy) that will be traced from the surroundings into the system and back out again. The amount of energy absorbed or released will be based on the number of bonds that are broken versus the number of new bonds formed in the chemical reaction.

After your instructor models the endothermic reaction, you will model an exothermic reaction on your handout using the same principles and ideas demonstrated in your instructor's model on the board. Then you will practice modeling two more chemical reactions; you will need to determine if these reactions are endothermic or exothermic during the modeling process to ensure the correct amount of energy absorbed or transferred throughout the chemical reaction