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Born-Haber Cycles. H bond energy of chlorine. Mg 2+ (g) + 2e - + 2Cl (g). Mg 2+ (g) + 2e - + Cl 2 (g). enthalpy H. H second ionisation energy. 2 x H first electron affinity. Mg + (g) + e - + Cl 2 (g). Mg 2+ (g) + 2Cl - (g). H first ionisation energy.
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Born-Haber Cycles H bond energy of chlorine Mg2+(g) + 2e- + 2Cl (g) Mg2+(g) + 2e- + Cl2(g) enthalpy H H second ionisation energy 2 x H first electron affinity Mg+(g) + e- + Cl2(g) Mg2+ (g) + 2Cl-(g) H first ionisation energy Mg (g) + Cl2 (g) H lattice H atomisation Mg (s) + Cl2(g) Mg (s) + Cl2 (g) H formation MgCl2(s) magnesium chloride
Born-Haber Cycles H bond energy of chlorine Mg2+(g) + 2e- + 2Cl (g) Mg2+(g) + 2e- + Cl2(g) enthalpy H H second ionisation energy 2 x H first electron affinity Mg+(g) + e- + Cl2(g) Mg2+ (g) + 2Cl-(g) H first ionisation energy Mg (g) + Cl2 (g) H lattice H atomisation Mg (s) + Cl2 (g) H formation MgCl2(s) magnesium chloride
Apply Hess’s Law to calculate ∆HLattice Energy for MgCl2setting out the values in a methodical manner: 1 = 2 + 3 + 4 + 5 + 6 + 7 -641 = +148 + 738 + 1451 + 242 + (2x-364) + ∆HLE -641 = + 1851 + ∆HLE ∆HLE = - 1851 - 641 = - 2492 kJ mol-1