Kc of the Forward/Reverse Reaction

Brandon Mo 4K
Posts: 70
Joined: Fri Sep 28, 2018 12:15 am

Kc of the Forward/Reverse Reaction

Why is it that when we know the Kc of the forward reaction, we also know the Kc of the reverse reaction? What is the relationship?

Michael Torres 4I
Posts: 92
Joined: Thu May 10, 2018 3:00 am
Been upvoted: 1 time

Re: Kc of the Forward/Reverse Reaction

The Kc of the reverse reaction is related to the Kc of the forward reaction because these two values are reciprocals of each other.

If the Kc of the forward reaction is X, then the Kc of the reverse reaction is 1/X.

Zubair Ahmed 1L
Posts: 81
Joined: Fri Sep 28, 2018 12:16 am

Re: Kc of the Forward/Reverse Reaction

The Kc is representative of both the forward and reverse reactions because they reaction rates are reciprocals of one another.One way to visually see this is by solving for the K value of both reactions and you will see that the two rates are the inverse of one another.

LaurenJuul_1B
Posts: 65
Joined: Fri Sep 28, 2018 12:17 am

Re: Kc of the Forward/Reverse Reaction

Think about when you reverse a reaction. The reactants and products will get flipped, so similarly, you just have to flip your value of Kc (take the inverse) and you will get the Kc of the reverse reaction since Kc is just a ratio.

Stevin1H
Posts: 89
Joined: Fri Sep 28, 2018 12:17 am

Re: Kc of the Forward/Reverse Reaction

The relationship between the forward reaction and the reverse reaction for K is that the equilibrium constant for the reverse reaction is the inverse of the forward reaction. Here is an example: N2(g) + 3H2(g) ⇌ 2NH3(g)

For the forward reaction:
Kc=(NH3)^2/((N2)(H2)^3)

For the reverse reaction:
Kc=((N2)(H2)^3)/(NH3)^2

If you look at both expressions, you will notice that the equilibrium constant expression for the reverse reaction is just the inverse of the forward reaction.

Zubair Ahmed 1L
Posts: 81
Joined: Fri Sep 28, 2018 12:16 am

Re: Kc of the Forward/Reverse Reaction

The Kc of the reverse reaction is the reciprocal of the forward reaction. For example, if the Kc of the forward reaction is 5, the Kc of the reverse reaction is 1/5.

Nghi Nguyen 2L
Posts: 61
Joined: Fri Sep 28, 2018 12:18 am

Re: Kc of the Forward/Reverse Reaction

they are just reciprocals of each other so for the forward reaction it's K and for the reverse reaction its 1/K