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NEET-XII-Chemistry

04: Chemical Kinetics

 page 3
Qstn# II-15-i Prvs-QstnNext-Qstn
  • #15-i
    Plot [N2O5] against t.
    () Find the half-life period for the reaction.
    () Draw a graph between log [N2O5] and t.
    () What is the rate law?
    () Calculate the rate constant.
    () Calculate the half-life period from k and compare it with (ii).
    Ans :




    () Time corresponding to the concentration, is the half life. From the graph, the half life is obtained as 1450 s.
    ()



    t(s)

    0
    		 1.63
    		 - 1.79
    400
    		 1.36
    		 - 1.87
    800
    		 1.14
    		 - 1.94
    1200
    		 0.93
    		 - 2.03
    1600
    		 0.78
    		 - 2.11
    2000
    		 0.64
    		 - 2.19
    2400
    		 0.53
    		 - 2.28
    2800
    		 0.43
    		 - 2.37
    3200
    		 0.35
    		 - 2.46




    () The given reaction is of the first order as the plot, v/s t, is a straight line. Therefore, the rate law of the reaction is


    () From the plot, v/s t, we obtain



    Again, slope of the line of the plot v/s t is given by

    .

    Therefore, we obtain,




    () Half-life is given by,



    This value, 1438 s, is very close to the value that was obtained from the graph.
  • #15-ii
    Find the half-life period for the reaction.
    Ans : Time corresponding to the concentration, is the half life. From the graph, the half life is obtained as 1450 s.
  • #15-iii
    Draw a graph between log [N2O5] and t.
    Ans :



    t(s)

    0
    		 1.63
    		 - 1.79
    400
    		 1.36
    		 - 1.87
    800
    		 1.14
    		 - 1.94
    1200
    		 0.93
    		 - 2.03
    1600
    		 0.78
    		 - 2.11
    2000
    		 0.64
    		 - 2.19
    2400
    		 0.53
    		 - 2.28
    2800
    		 0.43
    		 - 2.37
    3200
    		 0.35
    		 - 2.46




  • #15-iv
    What is the rate law?
    Ans : The given reaction is of the first order as the plot, v/s t, is a straight line. Therefore, the rate law of the reaction is


  • #15-v
    Calculate the rate constant.
    Ans : From the plot, v/s t, we obtain



    Again, slope of the line of the plot v/s t is given by

    .

    Therefore, we obtain,




  • #15-vi
    Calculate the half-life period from k and compare it with (ii).
    Ans : Half-life is given by,



    This value, 1438 s, is very close to the value that was obtained from the graph.