SOMEONE ASKED 👇
Calculate the lattice energy (U) of sodium oxide(Na2O) from the following data: please help!!!?
HERE THE ANSWERS 👇
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Lattice energy : energy released when ions in the gaseous state form a solid.
(1) Heat of formation: 2Na(s) + ½ O2(g) → Na2O(s) -416 kJ
(2)Sublimation: 2Na(s) → 2Na(g) 2(109) = 218 kJ
(3)Ionization: 2Na(g) → 2Na+(g) + 2e- 2(495) kJ = 990 kJ
(4) Dissociation: ½ O2(g) → O(g) ½)499kJ = 250 kJ
(5) Electron Affinity = O(g) + 2e- —→ O^2- = 603 kJ
(6)Lattice Energy = 2Na+(g) + O^2-(g) → Na2O(s)
(1) Heat of formation: 2Na(s) + ½ O2(g) → Na2O(s) -416 kJ (2)Sublimation: 2Na(g) → 2Na(s) 2(109) = -218 kJ Add (1) and (2) ===========================================(7) 2Na(g) + 1/2O2 ===⇒ Na2O(s) -634
reverse (3) 2Na+(g) + 2e- → 2Na(g) -990 Add (7) & 3(reversed) Note sign change
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(8) 2Na+ + 1/2O2(g) + 2e- ===⇒ 2Na2O -1624
reverse (4) O(g) + ==⇒ 1/2O2(g) -250 (sign change)
reverse(5) O^2- =⇒ O(g) + 2e- -603 Add 8, (4) and (5) (sign change)
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Lattice Energy = 2Na+(g) + O^2-(g) → Na2O(s) Delta H = -2477 kJ
Values for Lattice energy in tables are positive numbers. The reaction
is exothermic, so the energy released is + 2477 kilojoules
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