A chemist studies the first-order thermal decomposition of liquid dinitrogen pentoxide, N2O5(l), which produces NO2(g) and O2(g). Two sealed flasks, each containing the same amount of pure N2O5(l), are placed in separate water baths: one bath is held at 25 °C and the other at 45 °C. No other experimental conditions are changed.
(a) Predict whether the initial rate in the 45 °C flask is higher, lower, or the same as the rate in the 25 °C flask. Justify your answer using molecular-level reasoning that refers explicitly to both collision frequency and the distribution of molecular energies.
(b) Identify the experimental variable that was intentionally altered in this comparison and state two variables that were held constant so that only the effect of that single factor could be observed.
(c) At 45 °C the chemist observes bubbles of gas forming much more rapidly than at 25 °C. Explain how this macroscopic observation is consistent with your answer to part (a).