R3.1 Proton transfer reactions (HL)
15 revision questions with answers for R3.1 Proton transfer reactions (HL). Read them here, or play the set as a class game on the projector. Free to host, and students join with a code.
pOH of a solution with pH 3 at 298 K?
- 3
- 11Right answer
- 7
- 17
What this set covers
Acids and bases at HL: pOH, Ka, Kb and pKa, the link Ka × Kb = Kw, pH of weak acid solutions, titration curves, salt hydrolysis, indicator choice, and buffer pH using the ratio [A⁻]/[HA].
- Common mix-up
- Students often assume every equivalence point is at pH 7: a weak acid with a strong base ends above 7, and aqueous ammonium chloride is below 7.
- Revision tip
- Sketch a weak acid titration curve and mark the half-equivalence point where pH equals pKa, then place the equivalence point and choose the indicator.
All 15 questions and answers
pOH of a solution with pH 3 at 298 K?
Answer: 11
Expression for Ka of a weak acid HA?
Answer: [H⁺][A⁻]/[HA]
Expression for Kb of ammonia?
Answer: [NH₄⁺][OH⁻]/[NH₃]
pKa is defined as…?
Answer: −log Ka
Of two weak acids, the stronger one has the…pKa?
Answer: Smaller
Ka × Kb for a conjugate acid–base pair equals…?
Answer: Kw
pKa + pKb for a conjugate acid–base pair at 298 K?
Answer: 14
pH of 0.10 mol dm⁻³ weak acid with Ka = 1.0 × 10⁻⁵?
Answer: 3
At the half-equivalence point of a weak acid–strong base titration, pH equals…?
Answer: pKa
pH at the equivalence point of a weak acid–strong base titration?
Answer: Above 7
pH of aqueous ammonium chloride at 298 K is…?
Answer: Below 7
Suitable indicator for a weak acid–strong base titration?
Answer: Phenolphthalein
Solution that resists pH change when small amounts of acid or base are added?
Answer: Buffer
Pair of substances that forms an acidic buffer?
Answer: CH₃COOH and CH₃COONa
pH of a buffer with [A⁻]/[HA] = 10 and pKa = 4.0?
Answer: 5.0
Play it as a class game
Play this set opens it in splycr, where you can host it for your class straight away. Hosting needs no account: put the room code on the projector, and students join from a phone with the code and their first name. Each question plays as multiple choice, and the three wrong options were written for that question.