What is the $\mathrm{S}-\mathrm{S}$ bond energy if ${\mathrm{\Delta H}}_{\mathrm{f}}°\left(\mathrm{Et}-\mathrm{S}-\mathrm{Et}\right)=-147 \mathrm{kJ}/\mathrm{mol}; {\mathrm{\Delta H}}_{\mathrm{f}}°\left(\mathrm{Et}-\mathrm{S}-\mathrm{S}-\mathrm{Et}\right)=-202\mathrm{kJ}/\mathrm{mol}$ and ${\mathrm{\Delta H}}_{\mathrm{f}}^{\mathrm{o}}\mathrm{S}\left(\mathrm{g}\right)=+233\mathrm{kJ}/\mathrm{mol}$?

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 $\mathrm{F}-\mathrm{Cl}$.

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

$∆{\mathrm{H}}_{\mathrm{f}}^{\mathrm{o}}$ of ${\mathrm{N}}_2\mathrm{O}=82\mathrm{ }\mathrm{kJ}\mathrm{ }{\mathrm{mol}}^{-1},$

$\mathrm{N}\equiv \mathrm{N}\mathrm{ }946\mathrm{ }\mathrm{kJ}\mathrm{ }{\mathrm{mol}}^{-1};$

$\mathrm{N}=\mathrm{N},\mathrm{ }418\mathrm{ }\mathrm{kJ}\mathrm{ }{\mathrm{mol}}^{-1};$

$\mathrm{O}=\mathrm{O},\mathrm{ }498\mathrm{ }\mathrm{kJ}\mathrm{ }{\mathrm{mol}}^{-1};$

$\mathrm{N}-\mathrm{O},\mathrm{ }607\mathrm{ }\mathrm{kJ}\mathrm{ }{\mathrm{mol}}^{-1}$

Calculate the average $\mathrm{O}-\mathrm{H}$ bond energy in ${\mathrm{H}}_2\mathrm{O}$ with the help of the following data.

$$\begin{gathered} \left(1\right) {\mathrm{H}}_2\mathrm{O}\left(l\right)\to {\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right); ∆{\mathrm{H}}_1=+40.6 \mathrm{kJ} {\mathrm{mol}}^{-1} \\ \left(2\right) 2\mathrm{H}\left(\mathrm{g}\right)\to {\mathrm{H}}_2\left(\mathrm{g}\right); ∆{\mathrm{H}}_2=-435.0 \mathrm{kJ} {\mathrm{mol}}^{-1} \\ \left(3\right) {\mathrm{O}}_2\left(\mathrm{g}\right)\to 2\mathrm{O}\left(\mathrm{g}\right); ∆{\mathrm{H}}_3=+489.6 \mathrm{kJ} {\mathrm{mol}}^{-1} \\ \left(4\right) 2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(l\right); ∆{\mathrm{H}}_4=-571.6 \mathrm{kJ} {\mathrm{mol}}^{-1} \end{gathered}$$

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