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Question
30.4 kJ is required to melt one mole of sodium chloride. The entropy change during melting is 28.4 JK−1 mol−1. Calculate the melting point of sodium chloride.
Solution
Given, ∆Hf (NaCl) = 30.4 kJ = 30400 J mol−1
∆Sf (NaCl) = 28.4 JK−1 mol−1
Tf = ?
∆Sf = `(∆"H"_"f")/"T"_"f"`
Tf = `(∆"H"_"f")/(∆"S"_"f")`
Tf = `(30400 "J mol"^-1)/(28.4 "J K"^-1 "mol"^-1)`
Tf = 1070.4 K
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