Dinitrogen pentoxide decomposes in a sealed, rigid container at 298K according to 2N2O5(g)→4NO2(g)+O2(g). The laboratory has a pressure sensor, a gas-tight syringe, a visible-light spectrophotometer, and a pH meter. Which of the following measurements would provide the most direct data for determining the rate of the decomposition?
a) Change in the total pressure inside the container as a function of time
b) Change in the partial pressure of O2 inside the container as a function of time
c) Absorbance of the reaction mixture at 450nm where NO2 shows weak coloration
d) Volume of gas removed periodically with the syringe and released to the atmosphere