Chapter 8, Problem 93SCQ

(a)

Interpretation Introduction

Interpretation:

The balanced chemical equation for the reaction of phosphorus with chlorine to form $PC{l}_3$ has to be determined.

Concept Introduction:

In a balanced equation the number of atoms of each element as a reactant is equal to the number of atoms of that element as a product.

Coefficient is a number placed before a formula in a chemical equation.

A balanced equation should be obeying the law of conservation of mass. Law of conservation of mass states that, the number of atoms remains constant throughout the reaction, simply it can be stated as follows, “during a chemical reaction atoms are neither be created nor be destroyed”.

(b)

Interpretation Introduction

Interpretation:

The enthalpy change of the reaction of $P_4$ and $C{l}_2$ to $PC{l}_3$ has to be determined.

Concept Introduction:

Bond energy or more correctly the bond dissociation enthalpy is the enthalpy change when breaking a bond in a molecule with the reactant and products in the gas phase.

${\Delta }_{r}H=\sum \Delta H\left(bondsbroken\right)-\sum \Delta H\left(bondsformed\right)$

Enthalpy of formation:

${\Delta }_{r}H=\sum {\text{Δ}}_{\text{f}}{\text{H}}^{\text{0}}\left(products\right)-\sum {\text{Δ}}_{\text{f}}{\text{H}}^{\text{0}}\left(\text{reactants}\right)$

(c)

Interpretation Introduction

Interpretation:

The bond dissociation enthalpy for $P-Cl$ bond has to be determined.

Concept Introduction:

Bond energy or more correctly the bond dissociation enthalpy is the enthalpy change when breaking a bond in a molecule with the reactant and products in the gas phase.

${\Delta }_{r}H=\sum \Delta H\left(bondsbroken\right)-\sum \Delta H\left(bondsformed\right)$

Enthalpy of formation:

${\Delta }_{r}H=\sum {\text{Δ}}_{\text{f}}{\text{H}}^{\text{0}}\left(products\right)-\sum {\text{Δ}}_{\text{f}}{\text{H}}^{\text{0}}\left(\text{reactants}\right)$