Problem: Lattice energies can also be calculated for covalent network solids using a Born-Haber cycle, and the network solid silicon dioxide has one of the highest ΔH°lattice values. Silicon dioxide is found in pure crystalline form as transparent rock quartz. Much harder than glass, this material was once prized for making lenses for optical devices and expensive spectacles. Use Appendix B and the following data to calculate ΔH°lattice of SiO2:Si(s) ⟶Si(g)                               ΔH° =  454 kJSi(g) ⟶Si4+(g) + 4e−                 ΔH° = 9949 kJO2(g) ⟶2O(g)                           ΔH° =   498 kJO(g) + 2e− ⟶O2−(g)                  ΔH° =   737 kJ

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Born-Haber Cycle:

Heat of Sublimation: Si(s) → Si(g)                      ΔH° = 454 kJ

Ionization Energy: Si(g) → Si4+(g) + 4 e            ΔH° = 9949 kJ

Heat of Dissociation: O2(g) → 2 O(g)                 ΔH° = 498 kJ

Electron Affinity: O(g) + 2 e → O2(g)               ΔH° = 737 kJ

Heat of Formation: Si(s) + O2(g) → SiO2(s)        ΔH° = –910.9 kJ

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Problem Details

Lattice energies can also be calculated for covalent network solids using a Born-Haber cycle, and the network solid silicon dioxide has one of the highest ΔH°lattice values. Silicon dioxide is found in pure crystalline form as transparent rock quartz. Much harder than glass, this material was once prized for making lenses for optical devices and expensive spectacles. Use Appendix B and the following data to calculate ΔH°lattice of SiO2:


Si(s) ⟶Si(g)                               ΔH° =  454 kJ
Si(g) ⟶Si4+(g) + 4e                 ΔH° = 9949 kJ
O2(g) ⟶2O(g)                           ΔH° =   498 kJ
O(g) + 2e− ⟶O2−(g)                  ΔH° =   737 kJ