Question

The heat of vaporisation $\&$ heat of fusion of $H _{2} O$ are $540 \,cal / g \,\& \,80 \,cal / g .$ 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)

$\Delta s _{ vap }=\frac{\Delta H _{ vap }}{ T _{ b }}=\frac{540}{373},...(1)$

$\Delta s _{\text {fusion }}=\frac{\Delta H _{\text {fúsion }}}{ T _{ m }}=\frac{80}{273} ....(2)$

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

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

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