Question

The ionic compound

MX (s) is formed from the metal
M(s) and the diatomic gas
X₂ (9) at standard conditions. Calculate the lattice energy given the following data:
Sublimation
energy
for
M(8)
Bond
energy
for
X₂(g)
lonization
energy
of
M(g)
Electron
affinity
of
X(g)
Enthalpy
of
198 kJ/mol
of
MX()
142 kJ/mol
525 kJ/mol
-372 kJ/mol
formation-639 kJ/mol

Answer 1

mark me brilliant

Step-by-step explanation:

The lattice energy (ΔHlatt) can be calculated using the following equation:

ΔHlatt = ΔHf - ΔHsub - 1/2 ΔHbond - ΔHIE - ΔHEA

where ΔHf is the enthalpy of formation of the ionic compound, ΔHsub is the sublimation energy of the metal, ΔHbond is the bond energy of the diatomic gas, ΔHIE is the ionization energy of the metal, and ΔHEA is the electron affinity of the gas.

Substituting the given values:

ΔHlatt = (-639 kJ/mol) - (198 kJ/mol) - 1/2(142 kJ/mol) - (525 kJ/mol) - (-372 kJ/mol)

ΔHlatt = -639 kJ/mol - 198 kJ/mol - 71 kJ/mol - 525 kJ/mol + 372 kJ/mol

ΔHlatt = -1061 kJ/mol

Therefore, the lattice energy of the ionic compound MX is -1061 kJ/mol. Note that the negative sign indicates that the process of forming the solid ionic compound from the separate ions is exothermic (releases heat).