$\mathrm{CH}_{4(\mathrm{~g})}+\mathrm{Cl}_{2(\mathrm{~g})} \longrightarrow \mathrm{CH}_3 \mathrm{Cl}_{(\mathrm{g})}+\mathrm{HCl}_{(\mathrm{g})}$

$3 \mathrm{H}_{2(\mathrm{~g})}+\mathrm{N}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{NH}_{3(\mathrm{~g})}$

$\mathrm{C}_2 \mathrm{H}_{2(\mathrm{~g})}+\frac{5}{2} \mathrm{O}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{CO}_{2(\mathrm{~g})}+\mathrm{H}_2 \mathrm{O}_{(l)}$

$\quad 2 \mathrm{C}_2 \mathrm{H}_{6(\mathrm{~g})}+7 \mathrm{O}_{2(\mathrm{~g})} \longrightarrow 4 \mathrm{CO}_{2(\mathrm{~g})}+6 \mathrm{H}_2 \mathrm{O}_{(\mathrm{l})}$

$224.96 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$112.48 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$312.10 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$426.24 \mathrm{~kJ} \mathrm{~mol}^{-1}$

15 kJ

10 kJ

-25 kJ

-15 kJ

202.74 kJ

-312.74 kJ

225.26 kJ

-325.06 kJ