The enthalpy of formation (ΔH_f) of carbon dioxide is negative. Which statement is true?

• A. The formation of CO_2 from its elements is an endothermic process.
• B. The formation of CO_2 from its elements releases energy to the surroundings.
• C. The formation of CO_2 from its elements does not involve any energy change.
• D. The formation of CO_2 from its elements absorbs energy from the surroundings.

Answer: (B)

Verified step by step guidance

1. Understand that the enthalpy of formation (\( \Delta H_f \)) refers to the heat change when one mole of a compound forms from its elements in their standard states.
2. Recall that a negative \( \Delta H_f \) means the reaction releases heat to the surroundings, indicating an exothermic process.
3. Recognize that the formation of carbon dioxide (CO_2) from carbon and oxygen involves a negative enthalpy change, so energy is released.
4. Conclude that the statement 'The formation of CO_2 from its elements releases energy to the surroundings' correctly describes the process.
5. Note that statements suggesting energy absorption or no energy change contradict the meaning of a negative enthalpy of formation.