Answer to Question #2632 in Inorganic Chemistry for Mandy

Question

Write down the Born-Haber cycle for SrBr[sub]2[/sub] formation.

Answer 1

1. Sr_(s) → Sr_(g) + VBr_2(g) → 2Br_(g) + B
2. Sr_(g) → Sr_(g)⁺ + e^- + IE_M1
Sr⁺_(g) → Sr_(g)²⁺+ e^- + IE_M2
Br + e → Br^- - EA_x
3. Sr²⁺ + 2Br^-→ SrBr₂ + U_L
4. Br_2(g) + Sr_(s) → SrBr₂ + ∆H_f
Therefore,
∆H_f = V + B + IE_M1 + IE_M2 - EA_x + U_L
V is the enthalpy of sublimation for metal atoms
B is the bond energy of halogen atom
IE_M is the ionization energy of the metal atom
EA_X is the electron affinity of halogen atom
U_L is the lattice energy (defined as exothermic here)