Question

The heat of vaporisation $\&$ heat of fusion of $H_{2}O$ are $540cal/g\&80cal/g.$ The ratio of $\frac{\Delta S_{vap}}{\Delta S_{\text{fusion }}}$ for $H_{2}O$ is:

• A. 6.75
• B. 9.23
• C. 4.94
• D. 0.202

Answer 1

Answer: (C)

$\Delta s_{vap}=\frac{\Delta H_{vap}}{T_b}=\frac{540}{373},...(1)$

$\Delta s_{\text{fusion }}=\frac{\Delta H_{\text{fuˊsion }}}{T_m}=\frac{80}{273}....(2)$

$\frac{\Delta s_{\text{vap }}}{\Delta {\text{ s }}_{\text{fusion }}}=\frac{\frac{540}{373}}{\frac{80}{273}}$

$=\frac{540}{373}\times \frac{273}{80}$

$=\frac{14742}{2984}=4.94$