Question

the potential energy diagram for the uncatalyzed decomposition of h₂o₂(l) is shown above. the arrows labeled a and b represent different amounts of energy. when i⁻(aq) is used as a catalyst, how do the magnitudes of a and b in the new reaction energy diagram compare to the uncatalyzed diagram shown above?

	energy a	energy b
b	smaller	smaller
c	smaller	unchanged
d	unchanged	smaller

Explanation:

Step1: Identify Energy A and B

Energy A is the activation energy (energy needed to start the reaction), and Energy B is the enthalpy change (ΔH, difference in energy between reactants and products).

Step2: Effect of Catalyst on Activation Energy (A)

A catalyst lowers the activation energy of a reaction. So, when \( \text{I}^- (aq) \) is used as a catalyst, the activation energy (A) becomes smaller.

Step3: Effect of Catalyst on Enthalpy Change (B)

A catalyst does not change the enthalpy change (ΔH) of a reaction because it only affects the reaction pathway, not the energy difference between reactants and products. So, Energy B (enthalpy change) remains unchanged.

Answer:

C. Smaller, Unchanged