Which of the following statements is true regarding the energy diagram provided?

i. The reaction is endothermic.
ii. The activation energy is +10 kJ.
iii. The reaction releases energy.
iv. The enthalpy of the reaction is –25 kJ.

• A. I only
• B. II and IV
• C. I and III
• D. II, III and IV

Answer: (D)

Verified step by step guidance

1. Examine the energy diagram provided. The y-axis represents Gibbs Free Energy, and the x-axis represents the reaction coordinate.
2. Identify the initial and final energy levels on the diagram. The initial energy level is higher than the final energy level, indicating that the reaction releases energy.
3. Determine the activation energy by finding the difference between the peak energy and the initial energy level. This is the energy barrier that must be overcome for the reaction to proceed.
4. Calculate the change in enthalpy (ΔH) by subtracting the final energy level from the initial energy level. A negative ΔH indicates an exothermic reaction.
5. Based on the analysis, evaluate the given statements: i. The reaction is endothermic (false), ii. The activation energy is +10 kJ (true if the peak is 10 kJ above the initial level), iii. The reaction releases energy (true), iv. The enthalpy of the reaction is –25 kJ (true if the final level is 25 kJ below the initial level).