Question 1
Multiple choiceEasy1 markAn exothermic reaction is carried out with and without a catalyst. The catalyst provides an alternative pathway, while the reactants and products are unchanged. How does compare?
Show answer and explanation
Answer: B. Enthalpy change depends on the enthalpies of the initial and final states, not on the pathway. Since those states are unchanged, is unchanged.
A: confuses the catalyst’s effect on activation energy with making the reaction enthalpy less negative.
C: assumes the alternative pathway changes the energy released, although the initial and final states are unchanged.
D: treats an alternative pathway as the reverse reaction; reversing a reaction reverses the sign of
Remember: Hess’s law makes pathway-independent.