Delivering the programme
R2.1 Amount of chemical change
This section involves the use of chemical equations to show the ratio of reactants to products in a reaction and the mole ratio in order to determine both the masses or volumes of reactants and products...
Delivering the programme
R1.4 (AHL) Entropy & spontaneity
This page covers entropy which is a measure of the dispersal or distribution of matter and/or energy in a system and relates it to the Gibbs energy, using the expression ΔG⦵ = ΔH⦵ − TΔS⦵, to determine...
Delivering the programme
R1.3 Energy from fuels
This section covers the fuels used by man. It involves writing chemical equations for combustion reactions, understanding the difference between renewable and non-renewable energy sources and the advantages...
Delivering the programme
R1.2 (AHL) Standard enthalpy changes & Born-Haber cycle
This AHL page effectively builds on Hess's law, firstly by using standard enthalpies of combustion and formation in thermodynamic calculations, and then by applying the law to the formation of ionic compounds...
Delivering the programme
R1.2 Energy cycles in reactions
This page combines the law of conservation with the facts that bond-breaking absorbs and bond-forming releases energy to arrive at Hess's law. The law, which states that the enthalpy change for a reaction...
Delivering the programme
R1.1 Measuring energy changes
This section distinguishes between exothermic and endothermic reactions depending on the direction of energy transfer between the system and the surroundings and explains that whether reactions are endothermic...
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Delivering the programme
S3.2 (AHL) Mass spectrometry, IR & 1H NMR spectroscopy
This AHL section looks at how mass spectrometry, infrared spectroscopy and 1H NMR spectroscopy can be used individually and collectively to help determine the structural identity of an organic molecule. ...
Delivering the programme
S3.1 (AHL) Periodic table - transition elements
This AHL section on periodicity covers the transition elements. It characterizes them as having an incomplete d sub-level in one of more of their oxidation states and explains why they form coloured compounds....
Delivering the programme
S3.1 Periodic table (3) - oxidation states
This is the third section on the periodic table and focuses on how to deduce the oxidation state of an atom in an ion or in its compounds and in its elemental state. The difference between oxidation state...
Delivering the programme
S3.1 Periodic table (2) - periodicity & trends
This section on the periodic table focuses on periodicity, i.e. the repeating trends in the properties of elements and their compounds across a period. This is exemplified by atomic radius, ionic radius,...