${H_2}{O_{(l)}} \to \,\,H_{(aq)}^ + + \,\,OH_{(aq)}^ - \,;\,\,\,\Delta H\,\, = \,\,57.32\,\,KJ\,;$
${H_2}_{(g)} + \,\,\frac{1}{2}\,\,{O_2}_{(g)} \to \,\,{H_2}{O_{(1)}}\,;\,\,\Delta H\,\, = \,\, - 286.20\,\,KJ$
$\Delta {H_r} = {\mkern 1mu} {\mkern 1mu} \Delta {H_{f({H_2}O,{\kern 1pt} {\kern 1pt} {l})}} - {\mkern 1mu} {\mkern 1mu} \Delta {\mkern 1mu} {H_{f({H_2}O,{\kern 1pt} {\kern 1pt} g)}} - \frac{1}{2}{\mkern 1mu} {\mkern 1mu} \Delta {H_{f{\kern 1pt} ({O_2},{\kern 1pt} g)}}{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} $
${\mkern 1mu} \therefore {\mkern 1mu} {\mkern 1mu} \, - 286.20{\mkern 1mu} {\mkern 1mu} = {\mkern 1mu} {\mkern 1mu} \Delta {H_{f({H_2}O{\kern 1pt} ({l}))}}$
$So,\,\,\Delta {H_{f({H_2}O\,,\,\,{l})}} = \,\, - 286.\,\,20$
${H_2}{O_{({l})}}\, \to \,\,H_{(aq)}^ + \, + \,\,OH_{(aq)}^ - \,\,;\,\,\,\Delta H\,\, = \,\,57.32\,\,KJ$
$\Delta {H_r} = \,\,\Delta H_{f({H^ + },\,\,aq)}^ \circ \,\, + \,\,\Delta H_{f(O{H^ - },\,\,aq)}^ \circ - \,\,\Delta H_{f({H_2}O\,,\,{l})}^ \circ $
$57.32\,\, = \,\,0\,\, + \,\,\Delta H_{f(O{H^ - },\,\,aq)}^ \circ - ( - 286.20)$
$\Delta H_{f(O{H^ - },\,\,aq)}^ \circ = \,\,57.32\,\, - \,286.20\,\, = \,\, - 228.88\,\,KJ$
$H - H$ બંધઊર્જા | $:\, 431.37 \,kJ\, mol^{-1}$ |
$C= C$ બંધઊર્જા | $:\, 606.10\, kJ \,mol^{-1}$ |
$C - C$ બંધઊર્જા | $:\, 336.49\, kJ\, mol^{-1}$ |
$C - H$ બંધઊર્જા | $:\, 410.50\, kJ\, mol^{-1}$ |
પ્રક્રિયા : $\begin{array}{*{20}{c}}
{H\,\,\,\,H} \\
{|\,\,\,\,\,\,\,\,|} \\
{C = C} \\
{|\,\,\,\,\,\,\,\,\,|} \\
{H\,\,\,\,H}
\end{array}\, + \,H - H\, \to \,\begin{array}{*{20}{c}}
{H\,\,\,\,H} \\
{|\,\,\,\,\,\,\,\,|} \\
{H - C - C - H} \\
{|\,\,\,\,\,\,\,\,\,|} \\
{H\,\,\,\,H}
\end{array}\,$