Thermodynamics 0.0 / 5 ? ChemistryEnthalpyA2/A-levelAQA Created by: DomCreated on: 04-06-13 12:05 Enthalpy of Formation One mole of COMPOUND is formed from its constituent ELEMENTS Delta Hf = products - reactants C(s)+ O2 (g) - CO2 (g) 1 of 10 Combustion Enthalpy change when one mole of SUBTANCE undergoes COMPLETE COMBUSTION in EXCESS oxygen. 2 of 10 Atomisation Enthalpy change when One mole of GASEOUS ATOMS is produced from an ELEMENT. Na (s) => Na (g) 1/2 H2 (g) => H (g) 3 of 10 Ionisation Energy Required to remove one mole of Electrons from one mole of GASEOUS ATOMS. Produces a 1+ ion. M (g) => M+ (g) + e- 4 of 10 Electron Affinity Enthalpy change when one mole of GASEOUS ATOMS gains ONE ELECTRON per ATOM X (g) + e- =>X- 5 of 10 Hydration When one mole of GASEOUS IONS is converted into AQUEOUS IONS hydration = -lattic enthalpy - sum of solution enthalpies 6 of 10 Solution One mole of SOLUTE DISSOLVES in a LARGE AMOUNT of WATER enough to prevent IONS INTERACTING Solution = -lattice enthalpy + sum of hydration enthalpies 7 of 10 Lattice enthalpy Enthalpy change when M+ (g) + X- (g) => MX(s) occurs Exothermic in forwards direction. Conditions 298K 100kPa 8 of 10 Bond dissociation One mole of COVALENT BOND is BROKEN in the GASEOUS STATE forming 2 FREE RADICALS 9 of 10 Born-Harber Cycle ELECTRON AFFINITY Atomisation of Cl Ionisation of Sodium Lattice enthalpy of NaCl Atomisation of Sodium Formation of NaCl 10 of 10
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