Born-Harber

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Created by
Rory

Cards (17)

  • Enthalpy of formation
    enthalpy change when 1 mol of a substance is formed from its pure elements with all substances in their standard states
  • Enthalpy change
    heat change at constant pressure
  • Enthalpy of combustion
    enthalpy change when 1 mol of a substance is burned completely in sufficient O2 with all substances in their standard states
  • First ionisation energy
    enthalpy change when each atom in 1 mol of gaseous atoms loses one electron
  • First electron affinity
    enthalpy change when each atom in 1 mol of gaseous atoms gains one electron
  • Enthalpy of atomisation
    enthalpy change when 1 mol of gaseous atoms is produced from an element in its standard state
  • Hydration enthalpy
    enthalpy change when 1 mol of gaseous ions forms aqueous ions
  • Bond dissociation enthalpy
    enthalpy change when 1 mol of covalent bonds is broken in the gaseous state
  • Lattice enthalpy of formation
    enthalpy change when 1 mol of a solid ionic compound is formed from its constituent ions in the gas phase
    EXOTHERMIC
  • Lattice enthalpy of dissociation
    enthalpy change when 1 mol of a soil ionic compound is broken up into its constituent ions in the gas phase
    ENDOTHERMIC
  • Born-Haber cycles are experiential method to determine a value for lattice enthalpy
  • F formation
    A atomisation
    I ionisation energy
    L lattice enthalpy of formation
  • Lattice enthalpy depends on:
    • size (e.g. NaCl NaBr NaI : LE decreases down the group as larger halide ions, weaker attraction, less energy to break)
    • charge (e.g. NaCl MgO : LE increases down the group as higher charge 2+ and 2-)
  • experimental - Born-Harber cycles
    theoretical - Perfect ionic model
  • Perfect ionic model:
    • purely ionic bonding
    • ions are point charges (take up no space)
    • all attraction is electrostatic
  • If born-harber and perfect ionic model are close, there is very little covalent character so the perfect ionic model is fairly accurate.
  • Experimental data (born-harber cycles) includes covalent character so is more reliable