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.

Answer 1

Heat required for 1 mole of NaCl for melting (q) = 30.4 K J

= 30.4 x 1000 J

∆S – entropy change = 28.4 J K^-1 mol^-1

Melting point = T_m = ?

∆S = q = T_m

∴ T_m = q / ΔS

T_m = (30.4 x 1000) / 28.4 = 10704 K

Melting point of NaCl = 1070.4 K.