Multistep Reaction Energy Profile - AP Chemistry

Reaction progress. Shows how far the reaction has proceeded from start to finish.

Use $\text{ΔE} = \text{E}{\text{products}} - \text{E}{\text{reactants}}$. Subtract reactant energy from product energy for net change.

The transition state is typically unstable. It exists at maximum energy and quickly decomposes to products or reactants.

Products have lower energy than reactants. Energy is released when products are more stable than reactants.

Step with the highest activation energy. The slowest step has the largest energy barrier to overcome.

Catalyst. Catalysts change reaction rate but not equilibrium position.

The heat change at constant pressure. Measures energy change when pressure remains constant during reaction.

It lowers the energy of the transition state. Provides an alternative pathway with reduced energy barrier.

Energy at the valley between peaks. Intermediates exist at local minima between transition state peaks.

Energy at the peak of the curve. The transition state occurs at the maximum energy point.

Reactants have higher energy than products. Final energy level below initial level indicates exothermic reaction.

The step with the lowest peak. The shortest peak represents the easiest step to complete.

Lower energy indicates greater stability. Species at lower energy positions are more thermodynamically stable.

Higher activation energy generally means slower reaction rate. Larger energy barriers require more thermal energy to overcome.

The peak of the rate-determining step. The highest transition state determines the overall reaction rate.

The rate-determining step. The step with highest activation energy limits overall reaction rate.

The activation energy of the reaction. Higher barriers require more energy to overcome for reaction.

It represents the rate-determining step. The tallest peak controls the overall reaction rate.

It is not directly meaningful; focus on energy changes. The area has no physical significance in energy profiles.

The step with the highest activation energy. The slowest step controls the overall reaction rate.

It lowers the activation energy of the reaction. Provides an alternative pathway with a lower energy barrier.

Products have higher energy than reactants. Energy is absorbed when products are less stable than reactants.

Exothermic reaction. Energy decreases from reactants to products, releasing heat.

It does not affect the overall energy change. Catalysts only affect reaction rate, not thermodynamic properties.

Exothermic reaction. Negative enthalpy change indicates energy release to surroundings.

Lower peaks for each step. Catalyst provides alternative pathway with reduced energy barriers.

Potential energy. Energy represents the stored chemical potential energy of species.

The energy difference between reactants and the transition state. This represents the energy barrier that must be overcome for the reaction to proceed.

The peak of the energy curve. The activation complex is the same as the transition state.