The gas-phase reaction 2 D → products was studied at 35 °C. The concentration of D was measured at regular intervals, and the results are listed below.
Time (s)
[D] (M)
0
0.150
100
0.120
200
0.100
300
0.082
400
0.070
500
0.060
600
0.050
Assume no side reactions occur.
(a) Using an appropriate graphical method, determine the order of the reaction with respect to D. Present the evidence that supports your conclusion.
(b) Determine the numerical value and units of the rate constant k for the reaction at 35 °C.
(c) Develop an algebraic expression for the time required for [D] to decrease to one-third of its initial value, based on the rate law you identified in part (a). Then calculate this time for the initial concentration given in the table.
(d) The data collector later reports an additional measurement: at 600 s the experimental concentration of D was 0.050 M. Compare this value with the concentration predicted by your kinetic model and comment on the validity of the model over the full 600 s interval.