Consider the three-step representation of a reaction mechanism. Step 1: cap A plus cap b rightarrow AB (fast) and the rate is equal to k cap A cap b Step 2: AB plus cap b rightarrow AB sub 2 (slow) and the rate is equal to k AB cap b Step 3: AB sub 2 plus cap b rightarrow AB sub 3 (fast) and the rate is equal to k open bracket AB sub 2 close bracket cap b Overall: cap A plus 3 cap b rightarrow AB sub 3 and the rate is equal to k cap A cap b squared Which explains why the rate law for the overall equation is not the same as the rate equation for the rate-determining step?
Answer
A
cap b is an intermediate; therefore the rate law is determined from the reactants in the previous step.
B
AB is an intermediate; therefore the rate law is determined from the reactants in the previous step.
C
The overall rate law is determined from the balanced equation.