For the reaction 2N2O5→4NO2+O2, the rate of reaction is given by dividing the rate of disappearance or appearance of a species by its respective stoichiometric coefficient:
Rate=−21dtd[N2O5]=41dtd[NO2]=dtd[O2]
We are given the individual rate expressions:
−dtd[N2O5]=k[N2O5]
dtd[NO2]=k′[N2O5]
dtd[O2]=k′′[N2O5]
Substituting these into the overall rate expression, we get:
21(k[N2O5])=41(k′[N2O5])=k′′[N2O5]
Dividing the entire equation by [N2O5]:
2k=4k′=k′′
From this equality, we can deduce:
4k′=2k⟹k′=2k
k′′=2k