Chapter 12, Problem 122IE

Interpretation Introduction

(a)

To determine:

The bond in polyvinyl chloride that have the lowest average bond enthalpy.

Solution:

The $\text{C}-\text{Cl}$ bond has lowest bond enthalpy.

Explanation:

Polyvinyl chloride have $\text{C}-\text{C}$ , $\text{C}-\text{H}$ and $\text{C}-\text{Cl}$ bonds. Their bond enthalpies are:

$\text{C}-\text{C}$ bond $=348\text{kJ/mol}$

$\text{C}-\text{H}$ bond $=413\text{kJ/mol}$

$\text{C}-\text{Cl}$ bond $=328\text{kJ/mol}$

Therefore, the bond with lowest average bond enthalpy is $\text{C}-\text{Cl}$ bond. The electronegativity difference between carbon and chlorine is high, therefore the bond is readily broken. Hence it has lowest bond enthalpy.

Conclusion:

The $\text{C}-\text{Cl}$ bond has lowest bond enthalpy.

(b)

Interpretation Introduction

To determine:

The bond which is most likely to break first.

(c)

Interpretation Introduction

To determine:

The overall enthalpy change for converting PVC to diamond.