The idea of reversibility of reaction is vital in a variety of chemical systems at different scales, ranging from
the processes that release carbon dioxide into our atmosphere to the reactions of ions within individual cells
in our bodies. Processes that are reversible will respond to a range of factors and can achieve a state of
dynamic equilibrium. In this unit, students investigate acid‐base equilibrium systems and their applications.
They use contemporary models to explain the nature of acids and bases, and their properties and uses. This
understanding enables further exploration of the varying strengths of acids and bases. Students investigate
the principles of oxidation and reduction reactions and the production of electricity from electrochemical
cells. 

Through the investigation of appropriate contexts, students explore the ways in which models and theories
related to acid‐base and redox reactions, and their applications, have developed over time and through
interactions with social, economic and ethical considerations. They explore the ways in which chemistry
contributes to contemporary debate in industrial and environmental contexts, including the use of energy,
evaluation of risk and action for sustainability, and they recognise the limitations of science in providing
definitive answers in different contexts. 

Students use science inquiry skills to investigate the principles of dynamic chemical equilibrium and how
these can be applied to chemical processes and systems. They investigate a range of electrochemical cells,
including the choice of materials used and the voltage produced by these cells. Students use the pH scale to
assist in making judgements and predictions about the extent of dissociation of acids and bases and about
the concentrations of ions in an aqueous solution.