Question

The equilibrium-constant expression for a reaction written in one direction is the __________ of the one for the reaction written for the reverse direction.

Answer 1

Answer:

•    reciprocal  

Explanation:

The equilibrium constant for an equilibrium reaction is the ratio of the equilibrium constant for the forward reaction, Kf, to the equilibrium constant for the reverse reaction, Kr:

• For A ⇄ B

• The forward reaction is: A → B, with rate constant is Kf = K₁ and
• The reverse reaction is: B → A, with rate constant Kr = K₂

            $K_{eq}=\dfrac{K_f}{K_r}=\dfrac{K_1}{K_2}$

When you write the reaction in the other reaction, the forward and the reverse reaction are exchanged:

• For B ⇄ A

• The forward reaction is B → A, with rate constant Kf = K₂
• The reverse reaction is A → B, with rate constant Kr = K₁

             

             $K'_{eq}=\dfrac{K_f}{K_r}=\dfrac{K_2}{K_1}$

As you see:

          $K'_{eq}=\dfrac{1}{K_{eq}}$

Thus, the equilibrium-constant expression for a reaction written in one direction is the    reciprocal___ of the one for the reaction written for the reverse direction.