Chapter 12, Problem 35QRT

Interpretation Introduction

Interpretation:

The equilibrium constant, ${\text{K}}_{\text{c}}$ for the reaction ${\text{PCl}}_{\text{5(g)}}\rightleftharpoons {\text{ PCl}}_{\text{3(g)}}{\text{ + Cl}}_{\text{2(g)}}$ has to be calculated.

Concept Introduction:

Equilibrium constant: At equilibrium the ratio of products to reactants (each raised to the power corresponding to its stoichiometric coefficient) has a constant value, K

For a general reaction,

  $\text{aA+bB}\rightleftarrows \text{cC+dD}$

  $\text{Equilibrium}\text{constant}\text{K}\text{=}\frac{{\left[\text{C}\right]}^{\text{c}}{\left[\text{D}\right]}^{\text{d}}}{{\left[\text{A}\right]}^{\text{a}}{\left[\text{B}\right]}^{\text{b}}}$

The concentration of solids and pure liquids do not change, so their concentration terms are not included in the equilibrium constant expression.