AP Chemistry · Unit 8
Acids and Bases
In short
Unit 8: Acids and Bases in AP Chemistry covers 11 topics: Introduction to Acids and Bases, pH and pOH of Strong Acids and Bases, Weak Acid and Base Equilibria, Acid-Base Reactions and Buffers and 7 more. Open each one for what you need to know, a self-check list and how it is tested on the exam.
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What is in Unit 8: Acids and Bases?
Unit 8: Acids and Bases
8.1 Introduction to Acids and Bases
- I can calculate pH and pOH from hydronium and hydroxide ion concentrations using negative logarithms.
- I can use the autoionization constant of water (Kw = 1.0 × 10^-14 at 25°C) to relate hydronium and hydroxide concentrations.
- I can explain that a neutral solution is defined by pH = pOH, which is 7.0 at 25°C.
8.2 pH and pOH of Strong Acids and Bases
- I can calculate the pH and pOH of a strong acid or strong base solution based on its initial concentration.
8.3 Weak Acid and Base Equilibria
- I can explain that weak acids only partially ionize, leaving the vast majority of molecules un-ionized, and that [H3O+] is much less than the initial acid concentration.
- I can calculate the pH of a weak acid solution using the initial acid concentration and Ka or pKa.
- I can explain that weak bases only partially ionize, leaving the vast majority of molecules un-ionized, and that [OH-] does not equal the initial base concentration.
- I can calculate the pH of a weak base solution using the initial base concentration and Kb or pKb.
- I can calculate the percent ionization of a weak acid or base from its pKa/pKb and initial concentration, or from equilibrium concentrations.
- I can relate the acid ionization constant and base ionization constant for a conjugate acid-base pair using Kw.
8.4 Acid-Base Reactions and Buffers
8.5 Acid-Base Titrations
- I can use a titration curve plotting pH against the volume of titrant added to summarize results from a titration.
- I can use the relationship at the equivalence point (moles of titrant added equals moles of analyte originally present) to obtain the concentration of the analyte for monoprotic acids or bases.
- I can determine the pKa of a weak acid or base from the pH at the half-equivalence point in a titration, where the conjugate acid and base have equal concentrations.
- I can determine the pH at the equivalence point based on the major species in solution, recognizing that strong acid-strong base titrations are neutral, while weak acid or weak base titrations produce basic or acidic solutions respectively.
- I can use titration curves for polyprotic acids to determine the number of acidic protons, identify the major species present at any point, and find the pKa associated with each proton.
8.6 Molecular Structure of Acids and Bases
- I can infer the relative strength of protons in a molecule based on its molecular structure, including the effects of electronegativity, inductive effects, and resonance on conjugate base stabilization.
8.7 pH and pKa
- I can predict the protonation state of an acid or base by comparing the pH of a solution to the pKa of the acid.
- I can explain how acid-base indicators change properties based on their protonated versus deprotonated states in response to pH.
- I can select an appropriate acid-base indicator for a titration by choosing one with a pKa close to the pH at the equivalence point.
8.8 Properties of Buffers
- I can state that a buffer contains large concentrations of a conjugate acid-base pair and describe how each component reacts with added acid or base.
8.9 Henderson-Hasselbalch Equation
- I can explain how the pH of a buffer is related to the pKa and the concentration ratio of the conjugate acid-base pair using the Henderson-Hasselbalch equation, and understand why adding small amounts of acid or base does not significantly change the pH.
8.10 Buffer Capacity
- I can explain that increasing the concentration of buffer components (while keeping their ratio constant) keeps the pH the same but increases the buffer capacity.
- I can predict that a buffer with more conjugate acid than base has a greater capacity for added base, and a buffer with more conjugate base than acid has a greater capacity for added acid.
8.11 pH and Solubility
Acids and Bases: common questions
What is in Unit 8: Acids and Bases?
It covers 11 topics: 8.1 Introduction to Acids and Bases; 8.2 pH and pOH of Strong Acids and Bases; 8.3 Weak Acid and Base Equilibria; 8.4 Acid-Base Reactions and Buffers; 8.5 Acid-Base Titrations; 8.6 Molecular Structure of Acids and Bases; 8.7 pH and pKa; 8.8 Properties of Buffers; 8.9 Henderson-Hasselbalch Equation; 8.10 Buffer Capacity; 8.11 pH and Solubility.
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