NEET Chemistry Chemical Kinetics Questions Solved


Hydrogen peroxide, H2O2 (aq) decomposes to H2O(l) and O2(g) in a reaction that is first order in H2O2 and has a rate constant k = 1.06×10-3 min-1.

(i) How long will it take for 15% of a sample of H2O2  to decompose?

(ii) How long will it take for 85% of a sample  to decompose?

Given : k = 1.06×10-3min-1

For first order reaction

  k =2.303tlog aa-x where [ x= 15100a=0.15a ]

or    t=2.303klog aa-x 

or    t=2.3031.06×10-3log aa-0.15a

       t= 2172.64 log 1.1764

 Time (t) =2172.64 ×0.07055

               = 153.29 min


(ii)   t=2.303klog aa-x            [for 85% completion]

       t=2.3031.06×10-3log aa-0.85a

   t= 2172.64 log 6.66

 Time (t) =2172.64 ×0.8234

               = 1789.11 min


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