Which of the following statements concerning energy changes in chemical reactions is false?

• A. Energy is always absorbed when a chemical bond is formed.
• B. Endothermic reactions require an input of energy from the surroundings.
• C. Exothermic reactions release energy to the surroundings.
• D. The total energy of the universe remains constant during a chemical reaction.

Answer: (A)

Verified step by step guidance

1. Understand the concept of energy changes in chemical reactions, focusing on bond formation and bond breaking.
2. Recall that energy is required to break chemical bonds (bond breaking is endothermic) and energy is released when chemical bonds are formed (bond formation is exothermic).
3. Analyze each statement: For example, the statement 'Energy is always absorbed when a chemical bond is formed' contradicts the fundamental principle that bond formation releases energy.
4. Review the definitions of endothermic and exothermic reactions: endothermic reactions absorb energy from the surroundings, while exothermic reactions release energy to the surroundings.
5. Remember the law of conservation of energy, which states that the total energy of the universe remains constant during any chemical reaction.