Assessment And Qualifications Alliance (AQA) GCSE Biology Paper 2 Practice Exam

In the Haber process, which synthesizes ammonia from nitrogen and hydrogen gases, operating at a temperature of 450°C serves as a compromise between the rate of reaction and the yield of ammonia produced. At higher temperatures, the reaction rate increases due to the greater kinetic energy of the molecules, allowing them to collide more frequently and with sufficient energy to overcome the activation energy barrier. However, the Haber process is exothermic, meaning that lower temperatures favor the formation of ammonia. Thus, if the temperature were significantly lowered, the reaction could proceed more effectively toward the production of ammonia, but the rate of reaction would slow down significantly, making the process inefficient in terms of production time. Consequently, 450°C is an optimal temperature that balances these two aspects: it is high enough to ensure a reasonable rate of reaction while still allowing for a decent yield of ammonia. In contrast, a much higher temperature would speed up the reaction but reduce ammonia yield, while a much lower temperature would increase yield but slow down the reaction rate unacceptably. Therefore, the specific temperature of 450°C is crucial for maximizing efficiency in ammonia production.