A sample of argon gas is maintained at low pressure so that particle interactions are negligible. Two Maxwell–Boltzmann kinetic-energy distributions for this gas, labeled Curve A and Curve B, are obtained under different thermal conditions.
• Curve A has its peak at a higher relative number of particles but at a lower kinetic-energy value than Curve B.
• The area under each curve is identical.
• A vertical line at an energy of 75 kJ is drawn on the same axis to represent the minimum energy required for a specific gas-phase reaction.
Answer the following questions about the two curves.
(1) Identify which curve corresponds to the higher temperature and justify your answer by referring to specific features of the two distributions.
(2) Compare the fraction of argon atoms possessing energies greater than 75 kJ in the two samples. Explain how the graphical information supports your conclusion.
(3) For the reaction that requires a minimum of 75 kJ, predict which sample would exhibit the greater initial reaction rate. Provide a detailed explanation that connects molecular-level observations to macroscopic rate behaviour.