I did not fully understand why reaction rates have to always be written as positive numbers. It was confusing why a negative sign is added if the concentration is already decreasing, and the reading did not clearly explain why this convention is necessary, instead of just allowing negative rates.

I did not fully understand what an “alternative pathway or mechanism” means. The reading says it lowers activation energy, but it did not clearly explain how the pathway is different or what actually changes during the reaction.