Chemistry - Thermochemistry Question with Solution | TestHub

$\text{2}\text{C(s)}\text{+}\frac{\text{1}}{\text{2}}{\text{O}}_{\text{2}}\text{(g)}\text{+}\text{3}{\text{H}}_{\text{2}}\text{(g)}\to {\text{C}}_{\text{2}}{\text{H}}_{\text{5}}\text{OH(l);}{\text{ΔH}}_{\text{f}}\text{=}-\text{277}\text{.7}\text{kJ}$
By doubling the reaction,
$\text{4}\text{C(s)}\text{+}{\text{O}}_{\text{2}}\text{(g)}\text{+}\text{6}{\text{H}}_{\text{2}}\text{(g)}\to \text{2}{\text{C}}_{\text{2}}{\text{H}}_{\text{5}}\text{OH;}{\text{ΔH}}_{\text{f}}\text{=}\text{2}\text{×}\text{}-\text{277}\text{.7}$
$=-555.4\text{kJ}$