What energy change occurs when a bond is broken?

What energy change occurs when a bond is broken?

• A. Exothermic
• B. Endothermic
• C. Catalytic
• D. Spontaneous

Answer: (B)

When a bond is broken, energy must be put in to overcome the attraction holding the atoms together. This input of energy corresponds to a positive enthalpy change, so the process is endothermic. In contrast, forming bonds releases energy (exothermic). Catalysts affect how fast the reaction proceeds but not the energy sign, and spontaneity relates to whether a process occurs on its own under given conditions, not the energy change of breaking a bond.

When a bond is broken, energy must be put in to overcome the attraction holding the atoms together. This input of energy corresponds to a positive enthalpy change, so the process is endothermic. In contrast, forming bonds releases energy (exothermic). Catalysts affect how fast the reaction proceeds but not the energy sign, and spontaneity relates to whether a process occurs on its own under given conditions, not the energy change of breaking a bond.