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### Kc of the Forward/Reverse Reaction

Posted: Fri Jan 11, 2019 1:34 am
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?

### Re: Kc of the Forward/Reverse Reaction

Posted: Fri Jan 11, 2019 7:43 am
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.

### Re: Kc of the Forward/Reverse Reaction

Posted: Fri Jan 11, 2019 9:59 am
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.

### Re: Kc of the Forward/Reverse Reaction

Posted: Fri Jan 11, 2019 10:04 am
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.

### Re: Kc of the Forward/Reverse Reaction

Posted: Thu Jan 17, 2019 10:30 am
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.

### Re: Kc of the Forward/Reverse Reaction

Posted: Thu Jan 17, 2019 11:40 am
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.

### Re: Kc of the Forward/Reverse Reaction

Posted: Thu Jan 17, 2019 1:53 pm
they are just reciprocals of each other so for the forward reaction it's K and for the reverse reaction its 1/K