The experiemental data for decomposition of N2O5

[2N2O5→ 4NO2 + O2]


in gas phase at 318 k are given below:


t/s



0



400



800



1200



1600



2000



2400



2800



3200



102 × [N2O5]/mol L-1



1.63



1.36



1.14



0.93



0.78



0.64



0.53



0.43



0.35



(i) plot N2O5 against t


(ii) Find the half-life period for the Reaction.


(iii) Draw a graph between log[N2O5]and t.


(iv) what is the rate law?


(v) Calculate the rate constant.


(vi) Calculate the half-life period from k and compare it with (ii)


(i)


(ii) initial conc.is 1.63 × 10-2 so half conc. is 0.815 × 10-2M From given information and graph t1/2 is 1440 sec.


(iii)


(iv) As log [N2O5] vs time is straight line given reaction is first order. Hence its rate law will be, Rate = k[N2O5]


(v) The slope of above graph is slope = 0.000209


K = 2.303 × slope


⇒ 4.82 × 10-4sec-1


Now, t1/2 = 0.693/K.


⇒ 0.693/4.82 × 10-4


⇒ t1/2 = 1438 sec. which is almost equal to (ii)


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