Chapter 9, Problem 9.78P

Interpretation Introduction

Interpretation:

The substances that contain bonds with no excess bond energy are to be determined.

Concept introduction:

Bond energy is the amount of energy needed to break a bond between two gaseous atoms. Bond energy is measured in $\text{kJ/mol}$.

Excess bond energy is the difference between the actual bond energy (BE) of any bond and average of the bond energy of the atoms present in it in molecular form. The formula to calculate excess bond energy in $\text{X}-\text{Y}$ bond is as follows:

$\text{Excess bond energy}={\text{BE}}_{\text{X}-\text{Y}}-\frac{1}{2}\left({\text{BE}}_{\text{X}-\text{X}}+{\text{BE}}_{\text{Y}-\text{Y}}\right)$

Bond polarity can be estimated by $\Delta \text{EN}$. $\Delta \text{EN}$ is the electronegativity difference between the atoms bonded to each other. The formula to calculate $\Delta \text{EN}$ in AB bond is as follows:

$\Delta \text{EN}=\left(\text{electronegativity of B}\right)-\left(\text{electronegativity of A}\right)$

Here, B is the electronegative atom and A is the electropositive atom.