The particles in a mixture of gas X and gas Y have a Boltzmann distribution as shown in diagram 1. X and Y react, and this reaction leads to a greater number of gas molecules being present. The reaction proceeds to completion. For experiment 1, the rise in volume is recorded every $10\,\text{s}$. Throughout the reaction, temperature and pressure are kept constant. The volume increase is displayed on the volume-time graph in diagram 2. For experiment 2, the experiment is carried out again with the same amounts of X and Y. A different temperature is chosen from that used in experiment 1, but the same pressure is maintained. The Boltzmann distribution for the second mixture of X and Y is shown in diagram 3. During the reaction, the temperature and pressure stay constant. Which curve on the volume-time graph would represent the increase in volume against time for experiment 2? (The original line for experiment 1 is shown again as a solid line.)
Chemistry 9701 · AS & A Level · Reaction kinetics