$CO_{2(g)}$ અને $H_2O$ ના $\Delta H_f$ અનુક્રમે $-395$ અને $ -286$ $kJ \,mol^{-1}$ છે........$KJ$
\(\Delta {H_{react}}\,\, = \,\,\sum \Delta {H_{products}}\, - \,\,\sum \Delta {H_{reac\tan ts}} \)
\( - 3129\,\,\,\, = \,\,[4\,\, \times \,\,\Delta {H_{C{O_2}}}\, + \,\,6\,\, \times \,\,\Delta {H_{{H_2}O}}]\,\, - \,\,[2\,\, \times \,\,\Delta {H_{{C_2}{H_6}}}]\)
\(= \,\,[4\,\, \times \,\,( - 395\,\, + \,\,6\,\, \times \,\,( - 286))]\)\([2\,\, \times \,\,\Delta {H_{{C_2}{H_6}}}] \)
\( 2\,\,\Delta {H_{{C_2}{H_6}\,}}\,\, = \,\, - \,167\,\,kJ\)
[ તત્વ માટે \(\Delta {H_f}\, = \,\,0]\,\,\,\, \Rightarrow \,\,\,\,\Delta {H_{{C_2}{H_6}}}\, = \,\,\, - \,\,83.5\,\,kJ\)
$CaO_{(s)}\,\, + \,\,{H_2}O_{(l)}\,\, \to \,\,Ca{(OH)_2}_{(s)}\,;\,\,\,........(i)$ $\,\Delta {H_{1.8\,^oC}} = \,\, - \,\,15.26\,\,K\,cal$
$H_2O_{(l)}\,$ $ \to $ ${H_{2{(g)}}}$ $+$ $\frac{1}{2}O_{2(g)}$ $\,\Delta {H_{1.8\,^oC}} = \,\, - \,\,68.37\,\,K\,cal$
$Ca_{(s)} + \frac{1}{2}O_{2(g)} = CaO_{(s)}$ $\,\Delta {H_{1.8\,^oC}} = \,\, \,\,-151.80\,\,K\,cal$