$H_{2(g)} + \frac{1}{2} O_{2(g)} → H_2O{(l)} + 68.3\,K\,cal$
$CH_{4(g)} + 2O_{2(g)} → CO_{2(g)} + 2H_2O_{(l)} + 210.8\,K\,cal$
તો $K\,cal$ સ્વરૂપમાં મિથેનની નિર્માણ ઉષ્મા શોધો.
\(\Delta H = {(\Delta {H_{f}})_{C{O_2}}} + {(\Delta {H_{f}})_{{H_2}O}} - {(\Delta {H_{f}})_{C{H_4}}}\)
\( - 210.8 = - 94.2 + 2 \times ( - 68.3) - {(\Delta {H_{f}})_{C{H_4}}}\)
\({(\Delta {H_{f}})_{C{H_4}}} = - 20.0\,k\,cal\)
$3 HC \equiv CH _{( g )} \rightleftharpoons C _{6} H _{6(\ell)}$
[આપેલ : $\Delta_{f} G ^{\circ}( HC \equiv CH )=-2.04 \times 10^{5}\, J mol ^{-1}$
$\Delta_{f} G ^{\circ}\left( C _{6} H _{6}\right)=-1.24 \times 10^{5}\, J mol ^{-1} ; R =8.314\,\left. J K ^{-1} mol ^{-1}\right]$