Chapter 17.3, Problem 5RQ

Interpretation Introduction

Interpretation: From the value of equilibrium constant, details about amount of reactant and product and extent to which reaction proceeds must be inferred.

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.

Answer to Problem 5RQ

For small value of $K$ ,

1. Amount of reactant is high.
2. Amount of product is low.
3. Extent of reaction is less or short.

Explanation of Solution

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.

For $K<1$ , equilibrium is towards left end or favored in backward direction. In such case reactant concentration is higher than product concentration that is ${\left[\text{A}\right]}^a{\left[\text{B}\right]}^b$< ${\left[\text{C}\right]}^c{\left[\text{D}\right]}^d$ . Hence extent to which reaction proceeds is also less.

Conclusion

For small value of $K$ ,

1. Amount of reactant is high.
2. Amount of product is low.
3. Extent of reaction is less or short.