Question

In nitration of benzene by mixed acid the rate of reaction will be:
A. `C_(6)H_(6) = C_(6) D_(6) = C_(6) T_(6)`
B. `C_(6) H_(6) gt C_(6) D_(6) gt C_(6) T_(6)`
C. `C_(6) H_(6) = C_(6) D_(6) gt C_(6) T_(6)`
D. `C_(6)H_(6) lt C_(6) D_(6) lt C_(6) T_(6)`

Answer 1

Correct Answer - A
We are now in a position to draw possible energy profiles. Since the `C - D` bond is stronger than the `C - H` bond, the P.E. of the `C_(6)D_(6)` reactant system will be lower than that of the `C_(6)D_(6)` reactant system. This will also be the case for the corresponding product system. Because the most important difference between the two system is the step leading to fission of the `C - H` and `C - D` bonds, both energy profiles may be combined and only this difference is then shown. The student should carefully compare the energy profile drawn here with the one given in the Text. This again illustrates the point that energy profiles are not always what they are meant to represent.