What is the heat of formation of $$\mathrm{HCl}_{(\mathrm{g})}$$ from following equation?

$$\mathrm{H}_{2(\mathrm{~g})}+\mathrm{Cl}_{2(\mathrm{g})} \rightarrow 2 \mathrm{HCl}_{(\mathrm{g})} \Delta_{\mathrm{f}} \mathrm{H}=-194 \mathrm{~kJ}$$

If $$\mathrm{Q}$$ is the heat liberated from the system and $$\mathrm{W}$$ is the work done on the system then first law of thermodynamics can be written as,

For isochoric process, the first law of thermodynamics can be expressed as

When certain volume of gas expands against a constant external pressure of $$2.40 \times 10^5 \mathrm{~Pa}$$ at 300 $$\mathrm{K}$$ to $$2.2 \times 10^{-3} \mathrm{~m}^3$$. If the work obtained is $$-0.048 \mathrm{~kJ}$$. What is the initial volume of the gas?