For a two-step reaction mechanism, the following potential energies are reported:
• Reactants: 10 kJ mol⁻¹
• Transition State 1: 75 kJ mol⁻¹
• Intermediate: 35 kJ mol⁻¹
• Transition State 2: 95 kJ mol⁻¹
• Products: –15 kJ mol⁻¹
Identify which step is rate-determining and state its activation energy in kJ mol⁻¹.