Chapter 17, Problem 17.65P

Interpretation Introduction

Interpretation:

The best representation of the system has to be chosen after the addition of two formula units of Y in the given system.

Concept Introduction:

Le-Chatelier’s principle states that, whenever a system at equilibrium is disturbed, the system will undergo reactions and try to cancel that effect and retain equilibrium. Here the disturbance means change in concentration of any of the component, change in temperature, pressure or volume.

But changes in the amount of pure liquids and solids which will not appear in the reaction quotient cannot have any effect.

Consider a reaction given below.

$\text{a A}\left(\text{s}\right)\text{ + b B}\left(\text{g}\right)\stackrel{}{\rightleftarrows }\text{ c C}\left(\text{g}\right)\text{ + d D}\left(\text{g}\right)$

The reaction co-efficient (Q) of this reaction can be written as follows,

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

Where,

  $\begin{array}{l}\text{Q = reaction quotient}\\ \left[\text{C}\right]\text{ = concentration of C}\\ \left[D\right]\text{ = concentration of D}\\ \left[B\right]\text{ = concentration of B}\\ \text{ b = stoichiometric co-efficient of B}\\ \text{ c = stoichiometric co-efficient of C}\end{array}$

Concentration of A is not included in the reaction quotient because A is a pure solid. So change in A will not cause any effect on other components.