# Problem: Born-Haber cycles were used to obtain the first reliable values for electron affinity by considering the EA value as the unknown and using a theoretically calculated value for the lattice energy. Use a Born-Haber cycle for KF and the following values to calculate a value for the electron affinity of fluorine:K(s) ⟶K(g)                                               ΔH° =       90 kJK(g) ⟶K+(g) + e−                                     ΔH° =     419 kJF2(g) ⟶2F(g)                                           ΔH° =     159 kJK(s) + 1/2F2(g) ⟶KF(s)                            ΔH° =    −569 kJK+(g) + F−(g) ⟶KF(s)                              ΔH° =   −821 kJ

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###### Problem Details

Born-Haber cycles were used to obtain the first reliable values for electron affinity by considering the EA value as the unknown and using a theoretically calculated value for the lattice energy. Use a Born-Haber cycle for KF and the following values to calculate a value for the electron affinity of fluorine:
K(s) ⟶K(g)                                               ΔH° =       90 kJ
K(g) ⟶K+(g) + e                                     ΔH° =     419 kJ
F2(g) ⟶2F(g)                                           ΔH° =     159 kJ
K(s) + 1/2F2(g) ⟶KF(s)                            ΔH° =    −569 kJ
K+(g) + F(g) ⟶KF(s)                              ΔH° =   −821 kJ