Unit 7: Equilibrium

Students will learn that any bond or intermolecular attraction that can be formed can be broken. These two processes are in a dynamic competition, sensitive to initial conditions and external perturbations. A change in conditions, such as addition of a chemical species, change and temperature, or change in volume can cause the rate of the forward or reverse reactions to fall out of balance. This is reinforced through the spiraling of the following ideas;
- Some reactions can occur in both forward and reverse directions, sometimes proceeding in each direction simultaneously.
- A system at equilibrium depends on the relationship between concentrations, partial pressures of chemical species, and equilibrium constant K.
- Systems at equilibrium respond to external stresses to offset the effect of the stress.
- The dissolution of a salt is a reversible process that can be influenced by environmental factors such as pH or other dissolved ions.

- Make observations or collect data from representations of laboratory setups or results, while attending to precision where appropriate.
- Explain how modifications to an experimental procedure will alter results.
- Represent chemical phenomena using appropriate graphing techniques, including correct scale and units.
- Represent visually the relationship between the structures and interactions across multiple levels or scales.
- Explain the degree to which a model or representation describes the connection between particulate-level properties and macroscopic properties.
- Provide reasoning to justify a claim using chemical principles or laws, or using mathematical justification.
- Explain the connection between experimental results and chemical concepts, processes, or theories.

Score a 3 or higher on the unit 7 progress check using the AP score scale:

72-100% = 5

58-71% = 4

42-57% = 3

27-41% = 2

0-26% = 1