Skip to content
Marlbridge

AP® Chemistry · Unit 8 · Topic 8.11

pH and Solubility: Topic Checklist (Chemistry 8.11)

Specific “I can…” statements for pH and solubility, each linked to the guide section and practice question that shows whether you can really do it.

Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.

Understanding

  • I can state the three kinds of ion that make a salt’s solubility depend on pH: a weak base, a weak acid or hydroxide. (Guide: “Which salts are sensitive to pH?”)
  • I can explain why salts such as AgCl, AgBr and AgI do not respond to acid. (Guide: Worked example 1; Practice Q1)
  • I can explain that K_sp stays constant when the pH changes, and that only the solubility changes. (Guide: “Removing an ion makes more solid dissolve”; Practice Q2)
  • I can say that this topic is qualitative: I will not be asked to calculate solubility at a given pH. (Guide: “What you will not be asked to do”)

Skills

  • I can write the equation for H₃O⁺ removing a basic anion or OH⁻, and the overall equation for a salt dissolving in acid. (Guide: Worked example 1; Practice Q6)
  • I can predict that a salt with a weakly acidic cation dissolves more as the pH rises, and write the reaction with OH⁻. (Practice Q3)
  • I can use pH and pK_a to decide whether an ion will be removed at a given pH. (Guide: “How much does the pH have to change?”; Practice Q4)
  • I can read solubility data collected at different pH values and decide whether a difference is larger than the precision of the measurement. (Guide: Worked example 2; Practice Q5)

Reasoning

  • I can explain a pH effect on solubility in three steps: the ion removed, Q compared with K_sp, and the direction of the shift. (Practice Q2, Q5, Q6)
  • I can tell a pH effect apart from the common-ion effect, for example when HCl is added to a chloride or NaOH to a hydroxide. (Guide: Worked example 1(e); Practice Q7)
  • I can explain why a solubility experiment needs a buffer with no common ion. (Guide: Worked example 2; Practice Q5)
  • I can plan a separation of two solids that uses a pH-sensitive solubility, and justify each step. (Practice Q7)

All ticked? Unit 8 is complete. Move on to Topic 9.1, Introduction to Entropy, or return to the course roadmap.

AP® and Advanced Placement® are trademarks registered by the College Board, which is not affiliated with, and does not endorse, this website. Marlbridge is an independent tuition provider. It is not an authorized AP course provider, an AP school or an exam centre, and these resources are not official College Board materials. Reading them or doing simulations does not meet the laboratory requirement of an AP science course.