The decomposition of dinitrogen pentoxide in carbon tetrachloride solution at 30C N2O52NO2+1/2O2 is first order in N2O5 with a rate constant of 4.10103min1. If the initial concentration of N2O6 is 0.447M. the concentration of N2O5 will be M after 525min have passed. The gas phase decomposition of phosphine at 120C PH3(g)1/4P4(g)+3/2H2(g) is first order in PH3 with a rate constant of 0.0180s1. If the initial concentration of PH3 is 0.0356M, the concentration of PH3 will be 0.00481M after s have passed. The decomposition of dinitrogen pentoxide in carbon tetrachloride solution at 30C N2O52NO2+1/2O2 is first order in N2O5. In one experiment, when the initial concentration of N2O5 was 1.05M, the concentration of N2O5 dropped to 3.06101M after 188 minutes had passed. Based on these data, the rate constant for the reaction is min1