For the reaction of the ammonium ion with nitrous acid, the net reaction is NH4 (aq) + HNO2(aq) yields N2(g) + 2H2O (l) + H (aq) If the initial concentration of nitrous acid is 1.00 M and after 48.1 s has elapsed, the concentration of nitrous acid has fallen to 0.78 M , what is the average rate of the reaction over this time interval?