## Fast Step/Slow Step

$K = \frac{k_{forward}}{k_{reverse}}$

Drew Myers 4G
Posts: 100
Joined: Sat Aug 17, 2019 12:17 am

### Fast Step/Slow Step

How do you know what step in a rxn mechanism is the slow/fast step? What does a slow/fast step even mean?

jisulee1C
Posts: 149
Joined: Thu Jul 25, 2019 12:17 am

### Re: Fast Step/Slow Step

Usually for the reaction mechanism it states whether or not the reaction is fast or slow. If the reaction step is slow than that is the rate determining step for the reaction. In addition you would know that the reverse reaction for the slow step is almost nonexistent while for the fast reaction the forward and reverse reaction could still be happening.

005384106
Posts: 101
Joined: Sat Aug 24, 2019 12:16 am

### Re: Fast Step/Slow Step

How do you determine which step is fast/slow?

asannajust_1J
Posts: 105
Joined: Wed Sep 11, 2019 12:16 am
Been upvoted: 1 time

### Re: Fast Step/Slow Step

If not indicated, the fast step will be in equilibrium and the slow step will not.

Diana Chavez-Carrillo 2L
Posts: 122
Joined: Fri Sep 28, 2018 12:18 am

### Re: Fast Step/Slow Step

Could someone please explain to me why the slowest step is favored rather than the fast step?

Maria Poblete 2C
Posts: 102
Joined: Wed Sep 18, 2019 12:15 am

### Re: Fast Step/Slow Step

The slowest step determines the rate because the reaction cannot proceed until the slowest step has gone to completion. Essentially, if you think about it like a group on a hike, the slowest person determines the pace of everyone because the group cannot go on without them.

Bryan Chen 1H
Posts: 58
Joined: Mon Jun 17, 2019 7:24 am

### Re: Fast Step/Slow Step

^ no matter how "fast" the fast one is the slowest one is always the determinant because each other reaction depends on it to also occur

Ryan Lee 1E
Posts: 50
Joined: Sat Aug 17, 2019 12:16 am

### Re: Fast Step/Slow Step

I believe that if it had multiple steps, they would either give you experimental data to determine the slow step or they would just tell you what the rate-limiting step is.