Chapter 15, Problem 15.79SP

Interpretation Introduction

Interpretation:

Whether the pure air contain appreciable amount of O₃ when O₂ and O₃ are in equilibrium needs to be determined. Also, the equilibrium concentration of O₃ needs to be calculated.

Concept introduction:

The equilibrium constant, $K_c$ is the ratio between product of the equilibrium concentrations of the products and the product of equilibrium concentrations of all reactants. All the concentrations are raised to the power of its coefficient in the balanced equation. Equilibrium constant for a particular reaction is always same at a particular temperature.

Equilibrium constant expression

$\begin{array}{l}\text{aA + bB }\rightleftharpoons \text{ cC + dD}\\ K_c=\frac{{\left[C\right]}^c{\left[D\right]}^d}{{\left[A\right]}^a{\left[B\right]}^b}\end{array}$

Following criteria are considered for equilibrium mixtures.

If $K_c>{10}^3$, the products predominate over reactants. Since K_c is very large, the reaction proceeds nearly to completion.

If $K_c<{10}^3$, the reactants predominate over products. Since K_c is very small, the reaction may not proceed to completion or may not proceed at all.

If K_c is between ${10}^{-3}-{10}^3$, appreciable concentration of both reactants and products are present in the equilibrium mixture.