#13.1
be able to define lattice energy as the energy change when one mole of an ionic solid is formed from its gaseous ions
#13.2
be able to define the terms:
i) enthalpy change of atomisation, ΔatH
ii) electron affinity
#13.3
be able to construct Born-Haber cycles and carry out related calculations
#13.4
know that lattice energy provides a measure of ionic bond strength
#13.5
understand that a comparison of the experimental lattice energy value (from a Born-Haber cycle) with the theoretical value (obtained from electrostatic theory) in a particular compound indicates the degree of covalent bonding
#13.6
understand the meaning of polarisation as applied to ions
#13.7
know that the polarising power of a cation depends on its radius and charge
#13.8
know that the polarisability of an anion depends on its radius and charge
#13.9
be able to define the terms ‘enthalpy change of solution, ΔsolH’, and ‘enthalpy change of hydration, ΔsolH’
#13.10
be able to use energy cycles and energy level diagrams to carry out calculations involving enthalpy change of solution, enthalpy change of hydration and lattice energy
#13.11
understand the effect of ionic charge and ionic radius on the values of:
i) lattice energy
ii) enthalpy change of hydration
#13.12
understand that, since some endothermic reactions can occur at room temperature, enthalpy changes alone do not control whether reactions occur
#13.13
know that entropy is a measure of the disorder of a system and that the natural direction of change is increasing total entropy (positive entropy change)
#13.14
understand why entropy changes occur during:
i) changes of state
ii) dissolving of a solid ionic lattice
iii) reactions in which there is a change in the number of moles from reactants toproducts
Students should be able to discuss typical reactions in terms of disorder andenthalpy change, including:
- dissolving ammonium nitrate crystals in water
- reacting ethanoic acid with ammonium carbonate
- burning magnesium ribbon in air
- mixing solid barium hydroxide, Ba(OH)2.8H2O, with solid ammonium chloride.
#13.15
understand that the total entropy change in any reaction is the entropy change in the system added to the entropy change in the surroundings, shown by the expression:
ΔStotal = ΔSsystem + ΔSsurroundings
#13.16
be able to calculate the entropy change for the system, ΔSsystem, in a reaction, given the entropies of the reactants and products
#13.17
be able to calculate the entropy change in the surroundings, and hence ΔStotal, using the expression:
\(ΔS_{\text{surroundings}} = - \dfrac{ΔH}{T}\)
#13.18
know that the balance between the entropy change and the enthalpy change determines the feasibility of a reaction and is represented by the equation
ΔG = ΔH − TΔSsystem
#13.19
be able to use the equation ΔG = ΔH − TΔSsystem to:
i) predict whether a reaction is feasible
ii) determine the temperature at which a reaction is feasible
#13.20
be able to use the equation ΔG = −RT ln K to show that reactions which are feasible in terms of ΔG have large values for the equilibrium constant and vice versa
#13.21
understand why a reaction for which the ΔG value is negative may not occur in practice
#13.22
know that reactions that are thermodynamically feasible may be inhibited by kinetic factors