Chapter 17.3, Problem 1RQ

Interpretation Introduction

Interpretation: Effect of addition of reactant to equilibrium reaction and equilibrium constant must be provided.

Concept introduction: When the rate at which forward and backward reaction occur become equal such that concentration of reactants and products remains to be constant, that state is described as equilibrium. It is indicated by double sided arrow $\rightleftharpoons$ . It can be physical or chemical in nature.

For an equilibrium reaction:

  $a\text{A}+b\text{B}\rightleftharpoons c\text{C}+d\text{D}$

The expression for equilibrium constant is:

  $K=\frac{{\left[\text{C}\right]}^c{\left[\text{D}\right]}^d}{{\left[\text{A}\right]}^a{\left[\text{B}\right]}^b}$

Where,

  $K$ is equilibrium constant.

  $\left[\text{A}\right]$ and $\left[\text{B}\right]$ are reactant concentrations for A and B.

  $\left[\text{C}\right]$ and $\left[\text{D}\right]$ are product concentrations for C and D.

a, b, c and d are coefficients of reactants.

Answer to Problem 1RQ

On addition of reactant, equilibrium shifts to right direction and equilibrium constant remains constant.

Explanation of Solution

When additional reactant is introduced to a reaction at equilibrium, equilibrium moves in forward direction to reduce reactant concentration and promote product formation. It is called Le Chatelier’s principle.

But as the equilibrium reaction moves to right, no change is seen in the magnitude of equilibrium constant.

Conclusion

On addition of reactant, equilibrium shifts to right direction and equilibrium constant remains constant.