NEET Chemistry Chemical Kinetics Questions Solved

BOARD

(a) A reaction is  first order in A and second order in b.

    (i) Write differential rate  equation.

    (ii) How is rate affected when concentration of B is tripled?

    (iii) How is rate affected when concentration of both A and B is doubled ?

(b) What is molecularity of  a reaction?

(a)  (i)  Differential rate equation 

            dxdt = rate = [A]1 [B]2

   (ii) Rate r= K[A]1 [B]2                .....(1)

        When concentration of B is increased three times then

         Rate,  r= K[A]1 [3B]2          ......(2)

    Dividing equation (2) by (1), we get

             r= 9 r1,  i.e. rate increases by nine times. 

   
(iii) When concentration of both A and B  are doubled, then

           r= K[2A]1 [2B]2                ......(3)

    Dividing equation (3) by (1), we get

             r= 8 r1,

  Hence rate increases by eight times.

(b) The number of reacting species (atoms, ions or molecules) taking part in an elementary reaction is called Molecularity of a reaction.

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