Question

Refer 25 20 15 10 B C 0 Reaction progress Use the reaction energy diagram above to answer the following questions. Calculate the activation energy, AG , for the step C to B kcal/mol Calculate the overall energy change, AG, for the process B to A. kcal/mol Which step is faster, (a) B to A or (b) B to C Submit Answer Try Another Version 8 item attempts remaining A LO Free Energy (kcal/mol)

Answer 1

The activation energy dG for the step C to B

= Energy of C - Energy of 2nd activated state

= (7 - 24) kcal/mol

= -17 kcal/mol

Overall energy change for the process B to A

= Energy of B - Energy of A

= (12 - 5 ) = 7 kcal/mol

Activation energy for the step B to A

= ( 18 - 12 ) = 6 kcal/mol

Activation energy for the step B to C

= (24 - 12) = 12 kcal/mol

Since the step B to A has lower energy of activation than the step B to C; hence the step B to A is faster than B to C.