Chapter 17, Problem 3STP

Interpretation Introduction

Interpretation: The correct equilibrium expression for the given equation is to be given.

Concept Introduction: Equilibrium expression is written as the ratio of the concentration of products to the concentration of the reactants where each concentration term is raised to the power equal to its coefficient as indicated in the balanced chemical equation.

Answer to Problem 3STP

Correct answer: The correct option is $\begin{array}{l}\frac{{\left[{\text{H}}_{\text{2}}\text{O}\right]}^{\text{2}}}{{\left[{\text{H}}_{\text{2}}\right]}^{\text{2}}\left[{\text{O}}_{\text{2}}\right]}\\ \end{array}$ .

Explanation of Solution

Reason for correct option: Balanced chemical equation is $2{\text{H}}_{\text{2 (}g\text{)}}+{\text{O}}_{\text{2 (}g\text{)}}$${\text{2 H}}_{\text{2}}{\text{O }}_{(g)}$

Coefficient of ${\text{H}}_{\text{2}}\text{O}$ is 2 , ${\text{O}}_{\text{2}}$ is 1 and ${\text{H}}_{\text{2}}$ is 2 in the balanced chemical equation and so are the powers to which they are raised in the equilibrium expression.

Conclusion

Reasons for incorrect options: In the remaining options, the powers to which the concentration terms are raised are not same as the coefficients of reactants and product as indicated in the balanced chemical equation.