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NEET-XII-Chemistry

04: Chemical Kinetics

 page 3
Qstn# II-15 Prvs-QstnNext-Qstn
  • #15
    The experimental data for decomposition of N2O5



    in gas phase at 318K are given below:






    t(s)
    		 0 400 800 1200 1600 2000 2400 2800 3200

    		1.63 1.36 1.14 0.93 0.78 0.64 0.53 0.43 0.35


    () 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).
    () 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 : null ()




    () 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.
    () 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-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.