Question

Calculate the free-energy change for the dissolution of 1 mole of nabr and 1 mole of nai at 298 k, given that the values of δh°soln are –1 and –7 kj/mol for nabr and nai. the corresponding values of δs°soln are +57 and +74 j/(mol·k).

Answer 1

The free energy, which has a symbol of ΔG° at standard conditions has the formula:

ΔG° = n(ΔH° - TΔS°)

For NaBr:
ΔG° = (1 mol)[(-1 kJ/mol)(1000 J/1 kJ) - (298 K)(57 J/mol·K)]
ΔG° = -17,986 J

For NaI:
ΔG° = (1 mol)[(-7 kJ/mol)(1000 J/1 kJ) - (298 K)(74 J/mol·K)]
ΔG° = -29,052 J