Answer:

Explanation:
One way to calculate the lattice energy is to use Hess's Law.
The lattice energy U is the energy released when the gaseous ions combine to form a solid ionic crystal:
Li⁺(g) + Cl⁻(g) ⟶ LiCl(s); U = ?
We must generate this reaction rom the equations given.
(1)  Li(s) + ½Cl₂ (g) ⟶ LiCl(s);      ΔHf°     = -409 kJ·mol⁻¹
(2) Li(s) ⟶ Li(g);                          ΔHsub =    161 kJ·mol⁻¹
(3) Cl₂(g) ⟶ 2Cl(g)                     BE        =   243 kJ·mol⁻¹
(4) Li(g) ⟶Li⁺(g) +e⁻                   IE₁         =   520 kJ·mol⁻¹
(5) Cl(g) + e⁻ ⟶ Cl⁻(g)                EA₁       =  -349 kJ·mol⁻¹
Now, we put these equations together to get the lattice energy.
                                                 <u>E/kJ </u> 
(5) Li⁺(g) +e⁻ ⟶ Li(g)                520
(6) Li(g) ⟶ Li(s)                         -161
(7) Li(s) + ½Cl₂(g) ⟶ LiCl(s)     -409
(8) Cl(g) ⟶ ½Cl₂(g)                   -121.5
(9) Cl⁻(g) ⟶ Cl(g) + e⁻               <u>+349</u>
       Li⁺(g) +  Cl⁻(g) ⟶ LiCl(s)     -862
The lattice energy of LiCl is  .
.