Chapter 16, Problem 55AE

Interpretation Introduction

Interpretation:

Equilibrium constant for below reaction has to be calculated.

  ${\text{PCl}}_{\text{3}}\left(g\right)+{\text{Cl}}_{\text{2}}\left(g\right)\rightleftharpoons {\text{PCl}}_{\text{5}}\left(g\right)$

Concept Introduction:

For equilibrium reaction rate of forward reaction is equal to rate of reverse direction. Consider a general reaction that is as follows:

  $a\text{A}+b\text{B}\rightleftharpoons c\text{C}+d\text{D}$

The expression for equilibrium constant is written as follows:

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

Here,

$K_{\text{eq}}$ is equilibrium constant

$\left[\text{A}\right]$, $\left[\text{B}\right]$, $\left[\text{C}\right]$ and $\left[\text{D}\right]$ are concentration of substances in reaction

$a$, $b$, $c$ and $d$ are coefficients of substances

Ratio of number of moles of substance to its volume in litres is termed as concentration term. The formula to calculate concentration is as follows:

  $\text{Concentration}=\frac{\text{number of moles}}{\text{volume (L)}}$