Calculate the $\mathrm{C}-\mathrm{C}$ bond enthalpy from the following data:

$\left(\mathrm{a}\right) \mathrm{C}\left(\mathrm{s}\right)⟶\mathrm{C}\left(\mathrm{g}\right); \mathrm{\Delta H}=170 \mathrm{kcal}$

$\left(\mathrm{b}\right) \frac{1}{2}{\mathrm{H}}_2\left(\mathrm{g}\right)⟶\mathrm{H}\left(\mathrm{g}\right); \mathrm{\Delta H}=52 \mathrm{kcal}$

$\left(\mathrm{c}\right)$ Heat of formation of ethane $=-20 \mathrm{kcal}$

$\left(\mathrm{d}\right) \mathrm{C}-\mathrm{H}$ bond enthalpy$=99 \mathrm{kcal}$

Calculate the enthalpy of formation of $\mathrm{HBr} \left(\mathrm{g}\right)$ from the following data:

${\mathrm{SO}}_2 \left(\mathrm{aq}\right)+\frac{1}{2}{\mathrm{O}}_2 \left(\mathrm{g}\right)\to {\mathrm{SO}}_3 \left(\mathrm{aq}\right); \mathrm{\Delta H}=-63.7 \mathrm{kcal}$

${\mathrm{Br}}_2\left(\mathrm{l}\right)+{\mathrm{SO}}_2 \left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right)\to 2\mathrm{HBr} \left(\mathrm{aq}\right)+{\mathrm{SO}}_3 \left(\mathrm{aq}\right); \mathrm{\Delta H}=-54 \mathrm{kcal}$

${\mathrm{H}}_2 \left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2 \left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right); \mathrm{\Delta H}=-68.4 \mathrm{kcal}$

$\mathrm{HBr} \left(\mathrm{g}\right)+\mathrm{aq}\to \mathrm{HBr} \left(\mathrm{aq}\right); \mathrm{\Delta H}=-20 \mathrm{kcal}$

The heat of combustion of graphite and diamond at $298 \mathrm{K}$ are $-393$ and $-395 \mathrm{kJ}/\mathrm{mole}$, respectively. The specific heat of these substances are $720$ and $505 \mathrm{J} {\mathrm{kg}}^{-1}{\mathrm{K}}^{-1}$, respectively. Calculate the heat of transformation of graphite into diamond at $273 \mathrm{K}$.

[Hint: $\mathrm{\Delta H}=(-393-(395\left)\right)+(0.720-0.505)\times \frac{12}{1000}\times (298-273)$]

Assume that the only change in volume is due to the production of hydrogen and calculate the work done in joules(in multiple of ${10}^3$) when $2.0$ moles of $\mathrm{Zn}$ dissolve in hydrochloric acid, giving ${\mathrm{H}}_2$ at $35°\mathrm{C}$ and $1 \mathrm{atm}$.

$\mathrm{Zn} \left(\mathrm{s}\right)+2\mathrm{HCl} \left(\mathrm{aq}\right)\to {\mathrm{ZnCl}}_2 \left(\mathrm{aq}\right)+{\mathrm{H}}_2 \left(\mathrm{g}\right)$

[Hint: $\mathrm{W}=-\mathrm{p\Delta V}=-{\mathrm{\Delta n}}_{{\mathrm{H}}_2}\mathrm{RT}$]

The enthalpy of tetramerization of $\mathrm{X}$ in gas phase $\left(4\mathrm{X}\left(\mathrm{g}\right)\to {\mathrm{X}}_4\left(\mathrm{g}\right)\right)$ is $-100 \mathrm{kJ}/\mathrm{mol}$ at $300 \mathrm{K}$. The enthalpy of vaporisation for liquid $\mathrm{X}$ and ${\mathrm{X}}_4$ are respectively $30 \mathrm{kJ}/\mathrm{mol}$ and $72 \mathrm{kJ}/\mathrm{mol}$ respectively. $\mathrm{\Delta S}$ for tetramerization of $\mathrm{X}$ in liquid phase is $-125 \mathrm{J}/\mathrm{K}$ $\mathrm{mol}$ at $300 \mathrm{K}$. What is the $\left|\mathrm{\Delta G}\right|$ at $300 \mathrm{K}$ for tetramerization reaction of $\mathrm{X}$ in liquid phase $\left(4\mathrm{X}\left(\mathrm{\ell }\right)⟶{\mathrm{X}}_4\left(\mathrm{\ell }\right)\right)$ in $(\mathrm{kJ}/\mathrm{mol})$ ?

Report the value of $\left|\mathrm{\Delta G}\right|$ by rounding off to two significant figures.

Calculate the enthalpy change for the reaction, ${\mathrm{Fe}}_2{\mathrm{O}}_3+3\mathrm{CO}\to 2\mathrm{Fe}+3{\mathrm{CO}}_2;$ from the following data:

$2\mathrm{Fe}+\frac{3}{2}{\mathrm{O}}_2\to {\mathrm{Fe}}_2{\mathrm{O}}_3; \mathrm{\Delta H}=-177.1 \mathrm{kcal}$

$\mathrm{C}+\frac{1}{2}{\mathrm{O}}_2\to \mathrm{CO}; \mathrm{\Delta H}=-32.8 \mathrm{kcal}$

$\mathrm{C}+{\mathrm{O}}_2\to {\mathrm{CO}}_2; \mathrm{\Delta H}=-94.3 \mathrm{kcal}$