Question

Consider the following reaction A(g) + B(g) --> AB(l) The table shows the data for [A] vs time.

Tell me the order of the reaction with respect to A. Provide a plot(graph) that supports your answer.

Give me the value of the rate constant with the appropriate units.

time (sec) [A], M

0 100

10 82

20 68

30 55

40 43

50 35

60 27

Answer 1

Solution:

Following is the Table prepared with the given Data in the problem (obtained using MS Excel), in...image format....

Step-1:

Following is the Plot of [A], M vs. Time (sec) obtained using MS Excel, using above Data , in ...image format...

Step - 2 :

Following is the Plot of ln[A] vs. Time (sec.) ..obtained using MS Excel and using above Data..in... image format

Step - 3:

From the above Plots as we can see the ln[A] vs. Time (sec) graph/plot is completely a Streight Line.

Therefore, we can surely say, that the Order of Reaction with respect to A would be the following:

   Order of Reaction = First Order ( i.e. w.r.t ... A )... (..Answer...)

Step - 4:

Since for First Order reactions, we have the following integrated rate law:

     i.e. ln[A] = ln[A]_o - kt

Where:    k rate constant

And,

Therefore the Slope = - k of the ln[A] vs. Time (sec) plot provided above.......for above First Order Reaction

Step - 5:

Therefore.... Slope = ( ln[A]₆₀ - ln[A]₀)/ (60 - 0 ) sec = (3.295 - 4.60 ) / 60 = - 1.30/60 = - 0.02175

OR,

   Slope = - 0.02175 i.e. = - k

Therefore:

  k = 0.02175 s ^-1........................... ( Answer )