Lesson 12.3.2

12.3.2 Buffer solutions Quiz: Pearson Edexcel Chemistry, Unit 12

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 12.3.2, Buffer solutions: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 12: Acid-base Equilibria, written with Revision Ninja.

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The 20 questions

  1. Which statement describes the defining property of a buffer solution?

    • Increases H+ concentration
    • Maintains pH 7
    • Prevents temperature change
    • Resists pH change

  2. Which pair of substances forms an acidic buffer solution?

    • NaOH and Na2SO4
    • NH3 and NH4Cl
    • CH3COOH and CH3COONa
    • HCl and NaCl

  3. Which species reacts with added H+ ions in an ethanoic acid buffer?

    • Ethanoate ions
    • Water molecules
    • Sodium ions
    • Ethanoic acid

  4. Which species reacts with added OH- ions in an ethanoic acid buffer?

    • Ethanoic acid
    • Ethanoate ions
    • Sodium ions
    • Hydrogen ions

  5. Which salt would be used with ethanoic acid to make a buffer?

    • Sodium chloride
    • Sodium ethanoate
    • Sodium hydroxide
    • Sodium nitrate

  6. Which component of an acidic buffer neutralises added hydroxide ions?

    • Weak acid
    • Water
    • Sodium ion
    • Conjugate base

  7. Which species removes added H+ ions in an ammonia and ammonium chloride buffer?

    • Water
    • Chloride ions
    • Ammonium ions
    • Ammonia

  8. Which expression correctly calculates the pH of an acidic buffer solution?

    • pH = pKa x log10([A-]/[HA])
    • pH = pKa - log10([A-]/[HA])
    • pH = pKa + log10([A-]/[HA])
    • pH = Ka + log10([HA]/[A-])

  9. A buffer contains 0.20 mol dm-3 HA and 0.10 mol dm-3 A- with Ka = 1.8 x 10^-5 mol dm-3. What is its pH?

    • 5.44
    • 3.44
    • 4.44
    • 4.74

  10. What is the pH of a buffer with equal concentrations of a weak acid and its salt, where the acid has pKa 4.76?

    • 9.52
    • 4.76
    • 2.38
    • 7.00

  11. A buffer must have pH 5.00 with pKa 4.76. What is the required ratio [A-]/[HA]?

    • 5.00
    • 10.0
    • 0.57
    • 1.74

  12. How many moles of sodium ethanoate must be added to 100 cm3 of 0.10 mol dm-3 ethanoic acid to make a buffer of pH 5.00 (pKa 4.76), assuming no volume change?

    • 0.0174 mol
    • 0.0100 mol
    • 0.0240 mol
    • 0.00574 mol

  13. What species is formed alongside water when ethanoic acid neutralises hydroxide ions in a buffer?

    • Ethanoate ions
    • Ethanol
    • Ethane
    • Hydrogen gas

  14. How can buffer capacity be increased without changing the buffer pH?

    • Decrease salt concentration
    • Increase acid ratio
    • Increase component concentrations
    • Add pure water

  15. A buffer has 0.10 mol HA and 0.10 mol A- in 1.0 dm3 (pKa 4.76). If 0.010 mol NaOH is added, what is the new pH?

    • 4.67
    • 9.13
    • 4.76
    • 4.85

  16. A buffer is made by mixing 40.0 cm3 of 0.200 mol dm-3 ethanoic acid with 10.0 cm3 of 0.200 mol dm-3 NaOH (pKa 4.76). What is the pH of the buffer?

    • 3.76
    • 4.76
    • 4.28
    • 5.24

  17. What happens to the pH of a buffer solution when diluted with water?

    • Becomes exactly 7.0
    • Increases significantly
    • Stays almost constant
    • Decreases significantly

  18. The most effective buffer range is about pKa plus or minus 1 pH unit. What is the effective range for a buffer with pKa 4.76?

    • About pH 0.8 to 2.8
    • About pH 3.8 to 5.8
    • About pH 6.8 to 8.8
    • About pH 4.2 to 4.4

  19. What is the pH of a buffer made from equal concentrations of ammonia and ammonium chloride, given that the pKa of NH4+ is 9.25?

    • 7.00
    • 11.10
    • 9.25
    • 4.75

  20. Why does a mixture of hydrochloric acid and sodium chloride fail to act as a buffer?

    • NaCl is acidic
    • Cl- cannot accept H+
    • Cl- neutralises OH-
    • HCl is insoluble

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