Question

In a study of the decomposition of nitrosyl bromide at 10 °C NOBr—+NO+ Br2 the concentration of NOBr was followed as a function of time. It was found that a graph of 1/[NOBr] versus time in seconds gave a straight line with a slope of 1.27 m?s and a y-intercept of 3.98 M? Based on this plot, the reaction is order in NOBr and the rate constant for the reaction is M??

Answer 1

Rate laws for (*) Zero order Reaction - diese Ky *) First order Reaction=) din [A] = - krt [4.] or In CAJ = -kyt + Inca.] Here, ta time [A] = Conch of A at timet CA].2 concentration of A at time St=0 for the Reaction (A —— Product 1 Also, Kr = Rate constant And, Second order Reaction => = kxt tam Ex) And rate law for any reaction having Order 22 is → kt om til en ing n-1

D) from above role law equatiens, we See that if we plot / CA] against time, then, we will obtain straight line only in case of first order reaction. Caccording to general formula :- y=mx+e) where, me slope c= intercepts My = cooddinales (eg. time & Cart here), Hence, the given reaction is first order in NoBr (Here (A) = NOBr) And, on comparing general formula (y=mx+C) with birst order reaction, we found that makr Le Rale constant is slope. Hence, Rare constant for the reaction is 1.27 M's,

2) given that graph of In CH₂O] vs time Cie. In CA] vs time ) is straight line. from given rate laws, it seems to be the case of first order Reaction. And, on comparing the role law of first order with general formula ly=mx+c), we found that ma-kv =-1068 x103 min-1 (given) Hence rate constant = k, = 1.68 x 10-3 min, and reaction is lirst order in HbO2 d that (3) from the given table, • Initial concentration of Nitamide = 0.976M lie at time = 0) • Aller time = 181 min., concentration becomes half of initial concentration, ie. 0.4885 0.976

* Henie ball lile lor reaction starting at taomin, is 181 min. * Again, at 362 min concentration of Nitra mide become hall of previous concentration (at 181 min.) ie 00488 = 0.244 M Hence, half life for reaction starting at t=181 min is 362-1812 l&limin. Here, it seems that hall life is independe- -ht of concentration of Nihaamide. Which is a feature of first order reaction. Hall life in first order = fem2 = tyhl-us (2) Hence, Reaction is first order 13) Rate const (K) = fm2 = 3.82 x103 min til