Unit 8: Acids and Bases

In this unit students will build on their knowledge of chemical equilibrium studied in unit 7. Students will recognize that the chemistry of acids and bases involves reversible proton-transfer reactions, with equilibrium concentrations being related to the strength of the acids and bases involved. Students will also cover buffered solutions which resist changes to pH when small amounts of acid or base are added. As a result of this unit students will know:
- How to calculate the values of pH and pOH based on Kw values and concentrations of all species present in a neutral solution (water).
- How to calculate the values of pH and pOH based on concentrations of all species in a solution of a strong acid or strong base.
- Explain the relationship among pH, pOH, and concentrations of all species in a solution of a monoprotic weak acid or weak base.
- Explain the relationship among the concentrations of major species in a mixture of weak and strong acids and bases.
- Explain the results from the titration of mono- or polyprotic acid or base solution, in relationship to the properties of the solution and its components.
- Explain the relationship between the strength of an acid or base and the structure of the molecule or ion.
- Explain the relationship between the predominant form of a weak acid or base in solution at a given pH and the pKa of the conjugate acid or the pKb of the conjugate base.
- Explain the relationship between the ability of a buffer to stabilize pH and the reactions that occur when an acid or a base is added to a buffered solution.
- Identify the pH of a buffer solution based on the identity and concentrations of the conjugate acid-base pair used to create the buffer.
- Explain the relationship between the buffer capacity of a solution and the relative concentrations of the conjugate acid and conjugate base components of the solution.

- Identify an appropriate theory, definition, or mathematical relationship to solve a problem.
- Explain the relationship between variables within an equation when one variable changes.
- Calculate, estimate, or predict an unknown quantity from known quantities by selecting and following a logical computational pathway and attending to precision (significant figures).
- Identify information presented graphically to solve a problem.
- Support a claim with evidence from representations or models at the particulate level, such as the structure of atoms and/or molecules.
- Make observations or collect data from representations of laboratory setups or results, while attending to precision where appropriate.
- Provide reasoning to justify a claim using chemical principles or laws, or using mathematical justification.
- Explain how potential sources of experimental error may affect the experimental results.

Score a 3 or higher on the unit 8 progress check using the AP score scale:

72-100% = 5

58-71% = 4

42-57% = 3

27-41% = 2

0-26% = 1