Question

For the melting of $NaCl$ heat required is $7.26kcalmo{l}^{-1}$ and $\Delta S$ increases by $6.73calmo{l}^{-1}{K}^{-1}$. The melting point of the salt is:

• A. ${805.75}^{o}C$
• B. $500K$
• C. $1.77K$
• D. ${1.77}^{o}C$

Answer 1

The correct option is A ${805.75}^{o}C$

Since melting occurs at constant pressure so

$d{S}_{fus}=\frac{dH}{T}$

$\Rightarrow T=\frac{dH}{dS}=\frac{7.26\times 1000}{6.73}$

or, $T=1078.75K$

$=(1078.75-273{)}^{o}C$

or, $T={805.75}^{o}C$.