Calculate the lattice energy for LiF(s) given the following:
A) -650. kJ/mol
B) -1047 kJ/mol
C)800. kJ/mol
D) 285 kJ/mol
E) none of these

Question

Calculate the lattice energy for LiF(s) given the following: 
A) -650. kJ/mol 
B) -1047 kJ/mol 
C)800. kJ/mol 
D) 285 kJ/mol 
E) none of these

Quizplus · Accepted Answer

The lattice energy can be calculated using the Born-Haber cycle, which involves several steps. Given the standard enthalpies of formation, vaporization, sublimation, and ionization energy, we can calculate the lattice energy. For LiF, we have:
ΔH°f(LiF) = -617 kJ/mol (given)
ΔH°sub(Li) = 161 kJ/mol (from tables)
IE(Li) = 520 kJ/mol (from tables)
EA(F) = -328 kJ/mol (from tables)
ΔH°f(F) = 0 kJ/mol (by definition)
The equation for calculating the lattice energy is:
Lattice energy = -[ΔH°f(LiF) + ΔH°sub(Li) + IE(Li) + EA(F) - ΔH°f(F)]
Substituting the values, we get:
Lattice energy = -[-617 + 161 + 520 - 328 - 0] = -1047 kJ/mol
Therefore, the best choice is B, which corresponds to -1047 kJ/mol.

Calculate the Lattice Energy for LiF(s) Given the Following