Physical chemistry - 5. Chemical energetics


I Enthalpy changes: ÄH of formation, combustion, hydration, solution, neutralisation and atomisation; bond energy; lattice energy; electron affinity

II Hess’ Law, including Born- Haber cycles

Learning outcomes

Candidates should be able to:

(a) * explain that some chemical reactions are accompanied by energy changes, principally in the form of heat energy; the energy changes can be exothermic (ÄH, negative) or endothermic

(b) explain and use the terms:

(c) calculate enthalpy changes from appropriate experimental results, including the use of the relationship enthalpy change = mcÄT

(d) explain, in qualitative terms, the effect of ionic charge and of ionic radius on the numerical magnitude of a lattice energy

(e) apply Hess’ Law to construct simple energy cycles, and carry out calculations involving such cycles and relevant energy terms, with particular reference to:

(f) construct and interpret a reaction pathway diagram, in terms of the enthalpy change of the reaction and of the activation energy (see Section 8)