question_answer

  The following data were obtained during the first order thermal decomposition of  at a constant volume

Experiment	time	Total pressure (atm)
I II	0 100	0.5 0.6

Calculate the rate constant of the reaction when total pressure is 0.65 atm.                                         [5] Or (a) For the given reaction, If , what is the value of (b) Sucrose decomposes in acid solution into glucose and fructose according to the first order rate law with  hrs. Calculate the fraction of sucrose which remains after 8 hrs. (c) For a chemical reaction variation in concentration In [R] vs time (min) plot is shown below. (i) What is the order of the reaction? (ii) What are the units of rate constant, k for the reaction?                                                                           [1+3+1]

Answer:

     + Initial at           a            0                  0 T = 0 time    (a - x)         x                  x     [1] Initial pressure is due to atm                                                                       At time t (100 s) pressure is due to  and Thus,                       x = 0.6 - 0.5                      = 0.1 atm                                    [1] (a - x) 0.5 - 0. 1 = 0.4 atm                       Thus,                                            [2] Or (a)                                          [1] (b)(half-life period) = 3 hrs After 8 hrs                                                   [3]  (c) Coordinates involve In [R] terms. Thus it may be first order reaction.  (i) Order =1                                                        (ii) Unit of rate constant=time-1