The decomposition of ammonia on a tungsten surface at 1100C NH31/2N2+3/2H2 is zero order in NH3. In one experiment, when the initial concentration of NH3 was 1.24E2M, the concentration of NH3 dropped to 2.86E3M after 2.12E+3 seconds had passed. Based on these data, the rate constant for the reaction is Ms1. The gas phase decomposition of nitrogen dioxide at 383C NO2(g)NO(g)+1/2O2(g) is second order in NO2 with a rate constant of 0.540M1s1. If the initial concentration of NO2 is 0.471M, the concentration of NO2 will be M after 15.6 seconds have passed