Question

$ 30.4\, kJ $ is required to melt one mole of $ NaCl $ . The entropy change during melting is $ 28.4\, J \,mol^{-1} K^{-1} $ . What is the melting point of sodium chloride?

• A. $ 1070.4 \,K $
• B. $ 535.2\, K $
• C. $ 273.1 \,K $
• D. $ 1007.4 \,K $

Answer 1

Answer: (A)

$NaCl(s\rightarrow NaCl(l)$
$\Delta S = \frac{\Delta H}{\text{Temp}}$
$T = \frac{\Delta H}{\Delta S}$
$ = \frac{30.4 \times 10^3}{28.4}$
$ = 1070.4\,K$