Final answer:
The average rate of change of [NO2] in the decomposition reaction of N2O5 is positive, as NO2 is being produced. The rate of formation of NO2 is determined by dividing the change in concentration of NO2 by both the time and its stoichiometric coefficient in the balanced equation.
Step-by-step explanation:
When considering the decomposition reaction of gaseous N2O5 to produce NO2 and O2, the balanced chemical equation is as follows:
2 N2O5 (g) → 4 NO2(g) + O2(g)
The equation tells us that for every 2 moles of N2O5 that decompose, 4 moles of NO2 are produced. Therefore, the average rate of change of [NO2] would be positive, as the concentration of NO2 increases over the course of the reaction.
To compare the rates of disappearance of reactants and appearance of products, we use their molar ratios as stated in the balanced equation. For instance, to get the rate of formation of NO2, divide the change in concentration of NO2 by the time taken and then by the stoichiometric coefficient, which is 4 in this case (because 4 moles of NO2 are produced for every mole of O2 that is produced).