$(I)$ ${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(l);$
$\Delta {H^o_{298\,K}} = - 285.9\,kJ\,mo{l^{ - 1}}$
$(II)$ ${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(g);$
$\Delta {H^o_{298\,K}} = - 241.8\,kJ\,mo{l^{ - 1}}$
તો પાણીની મોલર બાષ્પાયન એન્થાલ્પી .....$kJ\,mol^{-1}$
${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(l);$
$\Delta {H^o} = - 285.9\,kJ\,mo{l^{ - 1}}........(1)$
${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(g);$
$\Delta {H^o}= - 241.8\,kJ\,mo{l^{ - 1}}........(2)$
We have to calculate
${H_2}O(l) \to {H_2}O(g);\,\Delta {H^o} = ?$
On substracting eqn. $(2)$ from eqn. $(1)$ we get
${H_2}O(l) \to {H_2}O(g);$
$\Delta {H^o} = - 241.8 - ( - 285.9)$
$ = 44.1\,kJ\,mo{l^{ - 1}}$
$A.$ $I _2( g ) \rightarrow 2 I ( g )$
$B.$ $HCl ( g ) \rightarrow H ( g )+ Cl ( g )$
$C.$ $H _2 O ( l ) \rightarrow H _2 O ( g )$
$D.$ $C ( s )+ O _2( g ) \rightarrow CO _2( g )$
$E.$ પાણીમાં એમોનિયમ કલોરાઈડનું વિલયન (ઓગળવું)
કિલોજૂલ અને $C + O_2$ $\rightarrow$ $CO_2$ :$\Delta H = x$ કિલોજૂલ, તો $x$ ..... કિલોજૂલ થાય.