The bond dissociation enthalpy of $\text{H}_2$, $\text{Cl}_2$ and HCl are $434$, $242$ and $431$ kJ $\text{mol}^{-1}$ respectively. Calculate the enthalpy of formation of HCl.

$200$ mL of ethylene gas and $150$ mL of HCl gas were allowed to react at $1$ bar. Pressure to form gaseous ethyl chloride. What is the work done during the reaction?

Calculate the enthalpy change for the following reaction, using given bond energy (kJ/mol)
(C-H = $414$, H-O = $463$, H-Cl = $431$, C-Cl = $326$ and C-O = $335$)
$\text{CH}_3\text{OH}_{(g)} + \text{HCl}_{(g)} \rightarrow \text{CH}_3\text{Cl}_{(g)} + \text{H}_2\text{O}_{(g)}$

Calculate the work done when $1$ mole of an ideal gas is expanded reversibly and isothermally from initial pressure $10$ bar to final pressure $1$ bar at constant temperature $300$ K. [$R = 8.314 \text{ J K}^{-1} \text{ mol}^{-1}$]