For the reaction: 4 NO2 (g) + O2 (g) 2 N2O5 (g) a) What is the rate of formation of N2O5 in terms of the rate of disappearance of O2? b) If the rate of disappearance of O2 = 0.0037 mol L-1s-1 what is the rate of disappearance of NO2?

##4NO_2+O_2rarr2N_2O_5##
(a)
Since 1 mole of ##O_2## is used up for every 2 moles of ##N_2O_5## formed the rate of formation of ##N_2O_5## will be twice the rate of disappearance of ##O_2##.
(b)
Since 4 moles of ##NO_2## are used up for every mole of ##O_2## the rate of disappearance of ##NO_2## will be 4 times the rate of disappearance of ##O_2## = ##4xx0.0037=0.0148 mol.l^(-1).s^(-1)##