$Zn + \frac{1}{2}\,O_2$ $\rightarrow$ $ZnO + 84000 \,cal ……..$

$(i)$ $Hg +$ $\frac{1}{2}O_2$ $\rightarrow$ $HgO + 21700 \,cal …….$

$(ii)$ $Zn + HgO$ $\rightarrow$$ ZnO + Hg$ માટે પ્રક્રિયા ઉષ્મામાં ($\Delta H$)......$cal$ થશે.

Question

$Zn + \frac{1}{2}\,O_2$ $\rightarrow$ $ZnO + 84000 \,cal ……..$

$(i)$ $Hg +$ $\frac{1}{2}O_2$ $\rightarrow$ $HgO + 21700 \,cal …….$

$(ii)$ $Zn + HgO$ $\rightarrow$$ ZnO + Hg$ માટે પ્રક્રિયા ઉષ્મામાં ($\Delta H$)......$cal$ થશે.

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Solution

d
${\text{(i)}}\,{\text{Z}}{{\text{n}}_{{\text{(s)}}}} + \frac{1}{2}{O_2}(g) \to ZnO\,;\,\,\Delta H = - 84000\,cal$

$(ii)\,H{g_{(\ell )}} + \frac{1}{2}{O_{2(g)}} \to HgO\,;\,\,\Delta H = - 217000\,cal.$

$(iii)\,Z{n_{(s)}} + HgO \to \,ZnO + H{g_{(\ell )}};\,\,\Delta H = ??$

હેસના નિયમ અનુસાર $(iii) - (i) - (ii)$

$\Delta H$ $= -84000 + 21700 = -62300 \,calorie$

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