When a chemical bond is broken, _________ is released.

• A. Bond energy
• B. Heat
• C. Mass
• D. Pressure

Answer: (A)

The energy change being tested is how much energy is involved when a bond is broken. To break any chemical bond, you must supply energy to overcome the attraction holding the atoms together. The amount of energy required for a specific bond is called the bond energy. Because this energy must be supplied from the surroundings, breaking a bond is an endothermic process—energy is absorbed, not released. The energy release, if it happens at all, occurs when bonds form, not when they break. So bond energy is the term that describes the energy involved in breaking a bond. Heat can provide that energy, but it’s not the bond itself; mass and pressure don’t directly quantify the energy needed to break the bond.