Read following statements carefully and select the correct option.\ (I) The entalpy of solution of

Question

Read following statements carefully and select the correct option.\ (I) The entalpy of solution of $\mathrm{CaCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ in a large volume of water is endothermic to the extent of $3.5 \mathrm{kcal} / \mathrm{mol}$. If $\Delta H=-23.2 \mathrm{kcal}$ for the reaction,\ $\mathrm{CaCl}_{2(s)}+6 \mathrm{H}_{2} \mathrm{O}_{(l)} \longrightarrow \mathrm{CaCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}_{(s)}$ then heat of solution of $\mathrm{CaCl}_{2}$ (anhydrous) in a large volume of water is $-19.7 \mathrm{kcal} / \mathrm{mol}$.\ (II) For the reaction, $2 \mathrm{Cl}_{(g)} \longrightarrow \mathrm{Cl}_{2(g)}$; the sign of $\Delta H$ and $\Delta S$ are negative.\

Professor PC Thomas Classes · Answer

(b) : (I) $\mathrm{CaCl}_{2(s)}+$ excess $\mathrm{H}_2 \mathrm{O} \longrightarrow \mathrm{CaCl}_{2(	ext { aqq })}+q$
$
\frac{\mathrm{CaCl}_{2(a q)}+6 \mathrm{H}_2 \mathrm{O}_{(l)} \longrightarrow \mathrm{CaCl}_2 \cdot 6 \mathrm{H}_2 \mathrm{O}_{(s)}+23.2}{\mathrm{CaCl}_{2(s)}+6 \mathrm{H}_2 \mathrm{O}_{(l)} \longrightarrow \mathrm{CaCl}_2 \cdot 6 \mathrm{H}_2 \mathrm{O}_{(s)}+q+23.2}
$
$
\begin{aligned}
& 3.5=q+23.2 \
& q=-19.7
\end{aligned}
$
(II) $2 \mathrm{Cl}_{(\mathrm{g})} \longrightarrow \mathrm{Cl}_{2(\mathrm{~g})}$
$
\Delta H=-\mathrm{ve}, \Delta S=-\mathrm{ve}
$