Chapter 18, Problem 18.168P

(a)

Interpretation Introduction

Interpretation:

${\text{K}}_{\text{c}}$ of the reaction has to be calculated when $\text{0}{\text{.15 mol of PH}}_{\text{3}}{\text{BCl}}_{\text{3}}\left(\text{s}\right)$ is introduced into a $\text{3}\text{.0 L}$ container at a given temperature and $\text{8}{\text{.4×10}}^{\text{-3}}{\text{ mol of PH}}_{\text{3}}$.

Concept introduction:

An equilibrium constant $\left(K\right)$ is the ratio of concentration of products and reactants raised to appropriate stoichiometric coefficient at equlibrium.

For the general reaction

  $\text{aA+}\text{bB}\underset{}{\rightleftharpoons }\text{cC+dD}$

The relative strength of reaction can be also expressed quantitatively with an equilibrium constant as follows:

  ${\text{K}}_{\text{C}}\text{=}\frac{{\left(\text{aC}\right)}^{\text{c}}{\left(\text{aD}\right)}^{\text{d}}}{{\left(\text{aA}\right)}^{\text{a}}{\left(\text{aB}\right)}^{\text{b}}}$                                                                                            $\left(1\right)$

An equilibrium constant is $\left(K_c\right)$.

(b)

Interpretation Introduction

Interpretation:

The Lewis structure of the reactant has to be drawn.

Concept introduction:

The Lewis structure is based on the concept of the octet rule so that the electrons shared in each atom should have 8 electrons in its outer shell.

Sometimes the chemical bonding of a molecule cannot be represented using a single Lewis structure. In these cases, the chemical bonding is described by delocalization of electrons and is known as resonance.

All the possible resonance structures are imaginary whereas the resonance hybrid is real.

These structures will differ only in the arrangement of the electrons not in the relative position of the atomic nuclei.