Seema Saini Solutions for Chapter: Thermodynamics, Exercise 4: DPP 5.4

Bond energies of ${\mathrm{F}}_2$ and ${\mathrm{Cl}}_2$ are $153.0$and $2424 \mathrm{kJ} {\mathrm{mol}}^{-1}$ respectively. The heat liberated in the reaction is $111.0 \mathrm{kJ}$ Find out the bond energy of $\mathrm{F}-\mathrm{Cl}$.

$1/2{\mathrm{F}}_2+1/2{\mathrm{Cl}}_2\to \mathrm{FCl}$

The enthalpy of combustion of ${\mathrm{H}}_{2 }\left(\mathrm{g}\right)$ at $298 \mathrm{K}$ to give ${\mathrm{H}}_2\mathrm{O} \left(\mathrm{g}\right)$ is $-249 \mathrm{kJ} {\mathrm{mol}}^{-1}$ and bond enthalpies of $\mathrm{H}-\mathrm{H}$ and $\mathrm{O}=\mathrm{O}$ are $433 \mathrm{kJ} {\mathrm{mol}}^{-}$ and $492 \mathrm{kJ} {\mathrm{mol}}^{-1}$, respectively. What will be the bond enthalpy of $\mathrm{O}-\mathrm{H}$?

Calculate ${\mathrm{\Delta H}}_{\mathrm{r}}^{\mathrm{o}}$ for the reaction ${\mathrm{CH}}_2{\mathrm{Cl}}_2\left(\mathrm{g}\right)\to \mathrm{C}\left(\mathrm{g}\right)+2\mathrm{H}\left(\mathrm{g}\right)+2\mathrm{Cl}\left(\mathrm{g}\right)$. The average bond enthalpies of $\mathrm{C}-\mathrm{H}$ and $\mathrm{C}-\mathrm{Cl}$ bonds are $414 \mathrm{kJ} {\mathrm{mol}}^{-1}$ are $330 \mathrm{kJ} {\mathrm{mol}}^{-1}$.

Heat of hydrogenation of ethene is ${\mathrm{x}}_1$ and that of benzene is ${\mathrm{x}}_2$. Hence, what will be the resonance energy?

Using the data (all values in $\mathrm{kJ} {\mathrm{mol}}^{-1}$ at $25°\mathrm{C}$) given below:

(A) Enthalpy of polymerization of ethylene $=-72$ $\mathrm{kJ} {\mathrm{mol}}^{-1}$

(B) Enthalpy of formation of benzene $\left(\mathrm{l}\right)=49 \mathrm{kJ} {\mathrm{mol}}^{-1}$

(C) Enthalpy of vaporization of benzene $\left(\mathrm{l}\right)=144 \mathrm{kJ} {\mathrm{mol}}^{-1}$

(D) Resonance energy of benzene $=-152 \mathrm{kJ} {\mathrm{mol}}^{-1}$

(E) Heat of formation of gaseous atoms from elements in their standard states $\mathrm{H}=218 \mathrm{kJ} {\mathrm{mol}}^{-1}, \mathrm{C}=715 \mathrm{kJ} {\mathrm{mol}}^{-1}$

(F) Average bond energy of $\mathrm{C}-\mathrm{H}=415 \mathrm{kJ} {\mathrm{mol}}^{-1}$

What will be the bond energy of $\mathrm{C}-\mathrm{C}$ and $\mathrm{C}=\mathrm{C}$ respectively?

The average $\mathrm{Xe}-\mathrm{F}$ bond energy is $34 \mathrm{kcal}/\mathrm{mol}$, first I.E. of $\mathrm{Xe}$ is $279 \mathrm{kcal}/\mathrm{mol}$, electron affinity of $\mathrm{F}$ is $85 \mathrm{kcal}/\mathrm{mol}$ and bond dissociation energy of ${\mathrm{F}}_2$ is $38 \mathrm{kcal}/\mathrm{mol}$. Then, the enthalpy change for the reaction

${\mathrm{XeF}}_4\to {\mathrm{Xe}}^{+}+{\mathrm{F}}^{-}+{\mathrm{F}}_2+\mathrm{F}$ will be

If ${\mathrm{\Delta H}}_{\mathrm{f}}^{\mathrm{o}}\left({\mathrm{C}}_2{\mathrm{H}}_6\right)\left(\mathrm{g}\right)=-85 \mathrm{kJ} {\mathrm{mol}}^{-1}$, ${\mathrm{\Delta H}}_{\mathrm{f}}^{\mathrm{o}}\left({\mathrm{C}}_3{\mathrm{H}}_8\right)\left(\mathrm{g}\right)=-104 \mathrm{kJ} {\mathrm{mol}}^{-1}, \mathrm{\Delta H}°$  for $\mathrm{C}\left(\mathrm{s}\right)\to \mathrm{C}\left(\mathrm{g}\right)$ is $718 \mathrm{kJ} {\mathrm{mol}}^{-1}$ and heat of formation of $\mathrm{H}-$atom is  $218 \mathrm{kJ} {\mathrm{mol}}^{-1}$, then:

Enthalpy of atomisation of ${\mathrm{C}}_2{\mathrm{H}}_6 \left(\mathrm{g}\right)$ and ${\mathrm{C}}_3{\mathrm{H}}_8 \left(\mathrm{g}\right)$ are $620 \mathrm{kJ} {\mathrm{mol}}^{-1}$ and $880 \mathrm{kJ} {\mathrm{mol}}^{-1}$. Therefore,