5.2.1
Lattice Enthalpy
Section 5.2.1 covers lattice enthalpy as a measure of the strength of ionic bonding, the construction of Born–Haber cycles for simple ionic solids such as NaCl and MgCl₂ and the related calculations, the enthalpy changes of solution and hydration with their enthalpy cycles, and the qualitative effect of ionic charge and radius on lattice enthalpy and on hydration enthalpy.
Revision Notes
3 revision notes, in the order the specification teaches them.
Lattice Enthalpy and Born–Haber Cycles
Lattice enthalpy and Born–Haber cycles: definitions of atomisation, ionisation energy and electron affinity, constructing the cycle for NaCl and MgCl₂ and calculating the missing value.
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Lattice Enthalpy Trends and Covalent Character
Lattice enthalpy trends: charge and radius, the perfect ionic model against Born–Haber values, polarisation and covalent character in ionic compounds.
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Enthalpy of Solution and Hydration
Enthalpy of solution and hydration: definitions, energy cycles with lattice enthalpy, worked calculations and the effect of ionic charge and radius.
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Lattice Enthalpy Map
OCR A Level Chemistry A · 5.2.1 Lattice enthalpy
The whole section on one A4 page: atomisation and electron affinity, lattice enthalpy, Born–Haber cycles, 2+ ions, charge and radius, and solution and hydration.
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5.2.1
- a i
explanation of the term lattice enthalpy (formation of 1 mol of ionic lattice from gaseous ions, ΔLEH)
Revise - a ii
use of lattice enthalpy as a measure of the strength of ionic bonding in a giant ionic lattice (see also 2.2.2 b–c)
Revise - b (i)
use of the lattice enthalpy of a simple ionic solid (e.g. NaCl, MgCl2) and relevant energy terms for the construction of Born–Haber cycles
Revise - b (ii)
use of the lattice enthalpy of a simple ionic solid (e.g. NaCl, MgCl2) and relevant energy terms for related calculations
Revise - c (i)
explanation and use of the term enthalpy change of solution (dissolving of 1 mol of solute, ΔsolH)
Revise - c (ii)
explanation and use of the term enthalpy change of hydration (dissolving of 1 mol of gaseous ions in water, ΔhydH)
Revise - d (i)
use of the enthalpy change of solution of a simple ionic solid (e.g. NaCl, MgCl2) and relevant energy terms (enthalpy change of hydration and lattice enthalpy) for the construction of enthalpy cycles
Revise - d (ii)
use of the enthalpy change of solution of a simple ionic solid (e.g. NaCl, MgCl2) and relevant energy terms (enthalpy change of hydration and lattice enthalpy) for related calculations
Revise - e i
qualitative explanation of the effect of ionic charge on the exothermic value of a lattice enthalpy
Revise - e ii
qualitative explanation of the effect of ionic radius on the exothermic value of a lattice enthalpy
Revise - e iii
qualitative explanation of the effect of ionic charge on the exothermic value of an enthalpy change of hydration
Revise - e iv
qualitative explanation of the effect of ionic radius on the exothermic value of an enthalpy change of hydration
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