Read More
Date: 20-12-2020
653
Date: 23-9-2018
124
Date: 21-9-2018
120
|
For multistep mechanisms, there is often one step that is significantly slower than the other steps. This slowest step is referred to as the rate-determining step, as it limits the rate of the entire reaction. An analogy that illustrates this concept is an hourglass having two different sized openings. The rate of the sand falling to the bottom-most chamber is determined by the smaller of the two openings (Figure 1.1 “Rate-Determining Point in an Hourglass”). Similarly, the rate law of the overall reaction is determined from its rate-determining slowest step.
Figure 1.1. Rate-Determining Point in an Hourglass
Double hourglass with one opening smaller than the other, which determines rate
Example 9
The following reaction occurs in a two-step mechanism:
A → B + C (slow)
A + C → B + D (fast)
1. Determine the overall reaction equation.
2. Write the rate law for the overall reaction.
Solution
1. Add the two elementary steps together and cancel out any intermediates to give the overall reaction: 2 A → 2 B + D
2. Rate = k[A]2
|
|
تفوقت في الاختبار على الجميع.. فاكهة "خارقة" في عالم التغذية
|
|
|
|
|
أمين عام أوبك: النفط الخام والغاز الطبيعي "هبة من الله"
|
|
|
|
|
قسم شؤون المعارف ينظم دورة عن آليات عمل الفهارس الفنية للموسوعات والكتب لملاكاته
|
|
|