\(\Rightarrow-165 \times 10^{3}- T \times(-505)=0\)
\(\Rightarrow T =300\, K\)
$CO_{2(g)}$ અને $H_2O$ ના $\Delta H_f$ અનુક્રમે $-395$ અને $ -286$ $kJ \,mol^{-1}$ છે........$KJ$
$Mg^{2+}(aq) = -456.0; OH-(aq) = -1 57.3; Mg(OH)_2 (s) = -833.9$
$2 \mathrm{C}_{(\mathrm{s})}+2 \mathrm{O}_2(\mathrm{~g}) 2 \mathrm{CO}_2(\mathrm{~g}), \Delta \mathrm{H}=-787 \mathrm{KJ} ; \mathrm{H}_2(\mathrm{~g})+$$\mathrm{H}_2 \mathrm{O}, \Delta \mathrm{H}=-286 \mathrm{KJ}$
$\frac{1}{2} \mathrm{O}_2 \mathrm{C}_2 \mathrm{H}_2(g)+\frac{5}{2} \mathrm{O}_2(g) \rightarrow 2 \mathrm{CO}_2(g)+\mathrm{H}_2 \mathrm{O}(I), \Delta H=-1310KJ$
$(i)$ $H_{(aq)}^+ + OH^-= H_2O_{(l)} ,$ $\Delta H = -X_1\,kJ \,mol^{-1}$
$(ii)$ $H_{2(g)} + \frac{1}{2}O_{2(g)} = H_2O_{(l)},$ $\Delta H = -X_2\,kJ \,mol^{-1}$
$(iii)$ $CO_{2(g)} + H_{2(g)} = CO_{(g)} + H_2O_{(l)},$ $\Delta H = -X_3\, kJ\, mol^{-1}$
$(iv)$ $ C_2H_{2(g)}+ \frac{5}{2} O_{2(g)} = 2CO_{2(g)} + H_2O_{(l)},$ $\Delta H = -X_4\,kJ \,mol^{-1}$
તો $H_2O_{(l)}$ સર્જનઉષ્મા કેટલી હશે ?