${H_{2\left( g \right)}} + 1/2{O_{2\left( g \right)}} \to {H_2}{O_{\left( l \right)}};\Delta {H_2}$ હોય, તો
${C_{\left( {graphite} \right)}} + {O_{2\left( g \right)}} \to C{O_{2\left( g \right)}}\,;\Delta H = - 393.5\,kJ$
${H_{2\left( g \right)}} + 1/2{O_{2\left( g \right)}} \to {H_2}{O_{\left( l \right)}}\,;\,\Delta H = - 286.2\,kJ$
${C_2}{H_{4\left( g \right)}} + 3{O_{2\left( g \right)}} \to 2C{O_{2\left( g \right)}} + 2{H_2}{O_{\left( l \right)}}\,;\,\Delta H = - 1410.8\,kJ$
$CO_2(g) , CO(g)$ અને $H_2O(g)$ માટે $\Delta H^o_f$ના મૂલ્યો અનુક્રમે $-393.5, -110.5$ અને $-241.8\, kJ/mol$,
$CO_2(g) + H_2(g) \to CO(g) + H_2O(g)$ is :
કિલોજૂલ અને $C + O_2$ $\rightarrow$ $CO_2$ :$\Delta H = x$ કિલોજૂલ, તો $x$ ..... કિલોજૂલ થાય.