Chemistry

Problem

298\,\text{K}

, Reaction X has an activation energy of

45\,\text{kJ}\,\text{mol}^{-1}

, whereas Reaction Y has an activation energy of

60\,\text{kJ}\,\text{mol}^{-1}

. No other factors differ between the two reactions. Which statement about their initial rates at

298\,\text{K}

is most accurate? a) The initial rates will be nearly identical because a

15\,\text{kJ}\,\text{mol}^{-1}

activation-energy difference is negligible compared with the thermal energy available at

298\,\text{K}

. b) Reaction Y will proceed faster because its higher activation energy corresponds to a greater overall energy release. c) Reaction X will proceed faster because a larger fraction of its molecular collisions can overcome the smaller activation energy. d) The relative rates cannot be compared without knowing the pre-exponential (frequency) factor in the Arrhenius equation.

Browse the problem library