Question

One mole of ice is converted into water at $273K$. The entropies of $H_{2}O\left(s\right)$ and $H_{2}O\left(l\right)$ are $38.20$ $Jmo{l}^{-1}$ and $60.01$ $Jmo{l}^{-1}{K}^{-1}$ respectively. The enthalpy of change for the conversion is:

• A. $59.54Jmo{l}^{-1}$
• B. $5954Jmo{l}^{-1}$
• C. $595.4Jmo{l}^{-1}$
• D. $320.6Jmo{l}^{-1}$

Answer 1

The correct option is B $5954Jmo{l}^{-1}$

Equilibrium reaction, $H_{2}O\left(s\right)\rightleftharpoons H_{2}O\left(l\right)$.

$\Delta S=60.01-38.20$$=21.81Jmo{l}^{-1}{k}^{-1}$

For a reaction at equilibrium, $\Delta H=T\Delta S$.

$\Delta H=273\times 21.81Jmo{l}^{-1}=5954.13Jmo{l}^{-1}\simeq 5954Jmo{l}^{-1}$