Question

free energy (y - axis), reaction progression (x - axis). which line indicates a higher reaction rate?
○ a because it has a lower activation energy
○ b because it has a lower activation energy
○ a because its $\triangle g_{rxn}$ is much lower.
○ b because its $\triangle g_{rxn}$ is much lower.

Explanation:

1. Recall the relationship between activation energy and reaction rate: Lower activation energy means a faster reaction rate because fewer reactant molecules need to overcome the energy barrier.
2. Analyze the graph: Line B has a lower peak (activation energy) than line A.
3. Evaluate the options:

• Option 1 (A, lower activation energy): Incorrect, as A has a higher activation energy.
• Option 2 (B, lower activation energy): Correct, since B’s lower activation energy leads to a higher reaction rate.
• Options 3 and 4: Incorrect, because \(\Delta G_{\text{rxn}}\) (free energy change) does not directly determine reaction rate; activation energy does.

Answer:

B because it has a lower activation energy