\({C_6}{H_6}(l) + \frac{{15}}{2}{O_2}(g) \to 6C{O_2}(g) + 3{H_2}O(l)\)
\(\Delta H = - 3270\,kJ\,mo{l^{ - 1}}.....(i)\)
\(C(gr) + {O_2}(g) \to C{O_2}(g),\)
\(\Delta H = - 394\,kJ\,mo{l^{ - 1}}.....(ii)\)
\({H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(l),\)
\(\Delta H = - 286\,kJ\,mo{l^{ - 1}}.....(iii)\)
Formation of \(C_6H_6\)
\(6C(gr) + 3{H_2}(g) \to {C_6}{H_6}(l);\,\Delta H = ?.....(iv)\)
By multiplying eq. \((ii)\) with \(6\) and eq. \((iii)\) with \(3\) and adding we get,
\(6C(gr) + 3{O_2}(g) + 3{H_2}(g) + \frac{3}{2}{O_2}(g)\) \( \to 6CO{ _2}(g) + 6{H_2}O(l)\)
\(\Delta H = 6( - 394) + 3( - 286)\)
\( = ( - 2364) + ( - 858)\)
\( = - 3222\,kJ/mol\)
Now, by substracting eq. \((i)\) from \((v)\) we get
\(6C(gr) + 3{H_2}(g) \to {C_6}{H_6}(l)\)
\(\Delta H = - 3222 - ( - 3270) = + 48\,kJ/mol\)
$(i)$ $H_{(aq)}^+ + OH^-= H_2O_{(l)} ,$ $\Delta H = -X_1\,kJ \,mol^{-1}$
$(ii)$ $H_{2(g)} + \frac{1}{2}O_{2(g)} = H_2O_{(l)},$ $\Delta H = -X_2\,kJ \,mol^{-1}$
$(iii)$ $CO_{2(g)} + H_{2(g)} = CO_{(g)} + H_2O_{(l)},$ $\Delta H = -X_3\, kJ\, mol^{-1}$
$(iv)$ $ 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 ?
| પદાર્થ | $H _{2}$ | $C$(ગ્રેફાઈટ) | $C _{2} H _{6}( g )$ |
| $\frac{\Delta_{ C } H ^{\Theta}}{ kJmol ^{-1}}$ | $-286.0$ | $-394.0$ | $-1560.0$ |
તો,ઈથેનની સર્જન એન્થાલ્પી ........
$(i)$ $Hg +$ $\frac{1}{2}O_2$ $\rightarrow$ $HgO + 21700 \,cal …….$
$(ii)$ $Zn + HgO$ $\rightarrow$$ ZnO + Hg$ માટે પ્રક્રિયા ઉષ્મામાં ($\Delta H$)......$cal$ થશે.
$3 HC \equiv CH _{( g )} \rightleftharpoons C _{6} H _{6(\ell)}$
[આપેલ : $\Delta_{f} G ^{\circ}( HC \equiv CH )=-2.04 \times 10^{5}\, J mol ^{-1}$
$\Delta_{f} G ^{\circ}\left( C _{6} H _{6}\right)=-1.24 \times 10^{5}\, J mol ^{-1} ; R =8.314\,\left. J K ^{-1} mol ^{-1}\right]$
$\frac{1}{2}C{l_2}(g)\xrightarrow{{\frac{1}{2}{\Delta _{diss}}{H^\Theta }}}Cl(g)\xrightarrow{{{\Delta _{eg}}{H^\Theta }}}$ $C{l^ - }(g)\xrightarrow{{{\Delta _{Hyd}}{H^\Theta }}}C{l^ - }(aq)$
તો $\frac{1}{2}C{l_2}(g)$ ના $Cl^-_{(aq)}$ માં રૂપાંતમાં ઊર્જાનો ફેરફાર ............. $\mathrm{kJ\,mol}^{-1}$ જણાવો.
$({{\Delta _{diss}}H_{C{l_2}}^\Theta } = 240\,kJ\,mol^{-1}, {{\Delta _{eg}}H_{C{l}}^\Theta }= -349 \,kJ\,mol^{-1},$${{\Delta _{Hyd}}H_{C{l}}^\Theta }= -381 \,kJ\,mol^{-1})$