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 (∆H, negative) or endothermic
(b) explain and use the terms:
(i) enthalpy change of reaction and standard conditions, with particular reference to: formation, combustion, hydration, solution, neutralisation, atomisation
(ii) bond energy (∆H positive, i.e. bond breaking)
(c) calculate enthalpy changes from appropriate experimental results, including the use of the relationship
enthalpy change, ∆H = –mc∆T
(e) apply Hess’ Law to construct simple energy cycles, and carry out calculations involving such cycles and relevant energy terms, with particular reference to:
(i) determining enthalpy changes that cannot be found by direct experiment, e.g. an enthalpy change of formation from enthalpy changes of combustion
(ii) average bond energies
(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)
(a) * explain that some chemical reactions are accompanied by energy changes, principally in the form of heat energy; the energy
changes can be exothermic (∆H, negative) or endothermic
(b) explain and use the terms:
(i) enthalpy change of reaction and standard conditions, with particular reference to: formation, combustion, hydration, solution, neutralisation, atomisation
(ii) bond energy (∆H positive, i.e. bond breaking)
(c) calculate enthalpy changes from appropriate experimental results, including the use of the relationship
enthalpy change, ∆H = –mc∆T
(e) apply Hess’ Law to construct simple energy cycles, and carry out calculations involving such cycles and relevant energy terms, with particular reference to:
(i) determining enthalpy changes that cannot be found by direct experiment, e.g. an enthalpy change of formation from enthalpy changes of combustion
(ii) average bond energies
(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)
Enthalpy change of reaction from changes of formation:
Products - Reactants
Enthalpy change of formation from enthalpy changes of combustion:
Reactants - Products
Products - Reactants
Enthalpy change of formation from enthalpy changes of combustion:
Reactants - Products