Chemistry

Chemistry

Problem

The energy profile for a two-step mechanism is described below (all energies are relative to the reactants): • Transition State 1: 110 kJ • Intermediate: –20 kJ • Transition State 2: 60 kJ • Products: –40 kJ Which combination of overall enthalpy change (ΔH) and rate-determining step is correct? a) ΔH=−20 kJ; Step 1 is rate – determining\Delta H = -20\ \text{kJ};\ \text{Step 1 is rate\,–\,determining} b) ΔH=+40 kJ; Step 1 is rate – determining\Delta H = +40\ \text{kJ};\ \text{Step 1 is rate\,–\,determining} c) ΔH=−40 kJ; Step 1 is rate – determining\Delta H = -40\ \text{kJ};\ \text{Step 1 is rate\,–\,determining} d) ΔH=−40 kJ; Step 2 is rate – determining\Delta H = -40\ \text{kJ};\ \text{Step 2 is rate\,–\,determining}

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