In the presence of a tungsten catalyst at high temperatures, the decomposition of ammonia to nitrogen and hydrogen is a zero order process. If the rate constant at a particular temperature is 3.7*10^-6 mol/L*sec, how long will it take for an ammonia concentration to drop from an initial concentration of 5.0*10^-4 M to 5.0*10^-5 M? What is the half life of the reaction under these conditions?