બેન્ઝીનની દહન ઉષ્મા $-3268$, $CO_2$ ની નિર્માણ ઉષ્મા $-393.5$ અને $H_2O_{(l)}$ ની નિર્માણ ઉષ્મા $-285.8\, KJ$ છે.
\((1)\) \(6C(s)\,\, + \,\,3{H_2}(g)\,\, \to \,\,{C_6}{H_6}\,(\ell )\)
\({\text{(2)}}{\mkern 1mu} {C_6}{{\text{H}}_{\text{6}}}(l){\mkern 1mu} + {\mkern 1mu} {\mkern 1mu} {\text{7}}\frac{{\text{1}}}{{\text{2}}}{\mkern 1mu} {\mkern 1mu} {O_2}(g) \to {\mkern 1mu} {\mkern 1mu} {\text{6C}}{{\text{O}}_{\text{2}}}{\mkern 1mu} {\text{(g)}}{\mkern 1mu} {\mkern 1mu} + {\mkern 1mu} {\mkern 1mu} {\text{3}}{{\text{H}}_{\text{2}}}{\text{O}}{\mkern 1mu} {\text{(}}\ell {\text{)}}{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \Delta {\text{H}}{\mkern 1mu} {\mkern 1mu} = {\mkern 1mu} {\mkern 1mu} {\text{ - }}{\mkern 1mu} {\mkern 1mu} {\text{3268}}{\mkern 1mu} {\mkern 1mu} {\text{KJ}}\)
\({\text{(3)}}\,C(s)\,\, + \,\,{O_2}{\text{(g)}}\,\, \to \,\,{\text{C}}{{\text{O}}_{\text{2}}}{\text{(g)}}\,{\text{;}}\,\,\,\,\,\,\,\Delta {\text{H}}\,{\text{ }} = \,\,{\text{ - }}\,{\text{ 393}}{\text{.5}}\,\,{\text{KJ}}\)
\({\text{(4)}}\,\,{{\text{H}}_{\text{2}}}{\text{(g)}}\,\, + \,\,\frac{{\text{1}}}{{\text{2}}}\,{{\text{O}}_{\text{2}}}{\text{(g)}}\,\, \to \,\,{{\text{H}}_{\text{2}}}{\text{O(}}\ell {\text{)}}\,{\text{;}}\,\,\,\Delta {\text{H}}\,\, = \,\,{\text{ - }}\,{\text{285}}{\text{.8}}\,\,{\text{KJ}}\)
સમી \((3)\) અને \((4)\) ને અનુક્રમે \(6\) અને \(3\) વડે ગુણતાં અને પછી તેઓ ઉમેરતાં,
\({\text{6C(s)}}\,\, + \,\,{\text{6}}{{\text{O}}_{\text{2}}}(g)\,\, \to \,\,6C{O_2}(g)\,;\,\Delta H\,\, = \,\, - \,2361\,\,KJ\)
\( + \,\,\,\,\,\underline {3{H_2}(g)\,\, + \,\,\frac{3}{2}{O_2}(g)\,\, \to \,\,3{H_2}O(\ell );\,\,\Delta H\,\, = \,\, - \,\,857.4\,\,KJ} \)
\((5)\,\,6C(s)\,\, + \,\,3{H_2}\,\, + \,\,\frac{{15}}{2}\,{O_2}(g)\,\, \to \,\,6C{O_2}(g)\,\, + \,\,3{H_2}O(\ell )\)
\(\Delta H\,\, = \,\, - \,\,3218.4\,\,KJ\)
સમી \((2)\) માંથી સમી \((5)\) બાદ કરતાં
\(6C(s)\,\, + \,\,3{H_2}\, + \,\,\frac{{15}}{2}\,{O_2}(g)\,\, \to \,\,6C{O_2}(g)\)\( + \,\,3{H_2}O(\ell )\,;\)
\(\underline { - {C_6}{H_6}(\ell )\, + \,\,\frac{{15}}{2}\,{O_2}(g)\,\, \to \,\,6C{O_2}(g)\,\, + \,\,3{H_2}O(\ell )\,\,\Delta H\,\, = \,\, - \,3268.0\,\,KJ} \)
\(6C(s)\, + \,\,3{H_2}(g)\,\, \to \,\,{C_6}{H_6}(\ell )\,\,\,\,\,\Delta H\,\, = \,\,49.6\,KJ\)
$C_2H_5OH_{(l)}+{3O_2} _{(g)} \rightarrow 2{CO_2} _{(g)}+3{H_2O}_{(l)}$
બોમ્બ કેલેરીમીટર દ્વારા $25\,^oC$ તાપમાને ઉત્પન્ન થતી ઉષ્માનો જથ્થો $1364.47\, kJ\, mol^{-1}$ માપેલ છે. જો આદર્શતા માની લઇએ (assuming ideality) તો પ્રક્રિયાની દહન-એન્થાલ્પી $\Delta _CH$ કેટલા .......$kJ\, mol^{-1}$ થશે? $(R=8.314\, kJ\, mol^{-1})$
(નજીકનો પૂર્ણાક) આપેલ : $R =8.3\,J\,K ^{-1}\,mol ^{-1}$
$2Al + C{r_2}{O_3} \to A{l_2}{O_3} + 2Cr$