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 define a buffer by what it contains: large amounts of both members of a weak conjugate acid–base pair. (Guide: “What a buffer is”; Practice Q1)
- I can say which buffer member removes added acid and which removes added base. (Guide: “The two reactions that do the work”; Practice Q2)
- I can explain why a buffer’s pH sits near the pK_a of its weak acid rather than at 7. (Guide: “What a buffer is”; Revision notes)
Skills
- I can write the net ionic equation for the reaction of a buffer with added H₃O⁺ or OH⁻, for both HA / A⁻ and B / BH⁺ buffers. (Guide: Worked example 1; Practice Q2, Q5)
- I can calculate the amounts of both buffer members after a small amount of strong acid or base is added. (Guide: Figure 1; Practice Q4, Q5)
- I can work out what remains when a weak acid or base is mixed with a strong base or acid, and decide whether the result is a buffer. (Guide: Worked example 2; Practice Q3)
- I can find the largest amount of acid or base a buffer can react with before one member runs out. (Practice Q5(c))
Reasoning
- I can explain at the particle level why added acid or base changes the pH of a buffer much less than the pH of water. (Guide: “Why this keeps the pH steady”; Practice Q6)
- I can explain why a strong acid with its salt, or a weak acid on its own, is not a buffer. (Guide: “How buffers are made”; Practice Q7)
- I can use measured pH data to support a claim that a solution is buffered. (Practice Q6)
All ticked? Move on to Topic 8.9, the Henderson–Hasselbalch Equation, or return to the course roadmap.