Chapter 17, Problem 32A

Interpretation Introduction

Interpretation: The effect of addition of reactant in the reaction equilibrium needs to be determined.

Concept introduction: According to Le Chatelier's principle if any stress is given to the equilibrium, it will shift in a direction to reduce the given stress. If change in concentration, pressure or temperature takes place at equilibrium, it will shift in the direction to undo the change or its effect.

Answer to Problem 32A

d is the correct option.

Explanation of Solution

The concerned reaction: $2H_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2H_{2}O\left(g\right)$

Equilibrium constant for the reaction is given by the equation, $K=\frac{{\left[H_{2}O\right]}^2}{{\left[H_2\right]}^2\left[O_2\right]}$

If we add a reactant ( $H_2$ ) then the value of $K$ will decrease since the concentration of $H_2$ is in denominator. To maintain the value of $K$ , concentration of the products ( $H_{2}O$ ) must increase.

Hence, the concentration water vapor increases.

Conclusion

Hence, upon addition of reactant ( $H_2$ ) the value $K$ will not change. So, option b and e cannot be the answer.

Since, upon addition of reactant ( $H_2$ ) the reaction shifts in forward direction concentration of the $O_2$ will decrease. So, option a and c cannot be the answer.