Lesson 12.4.1

12.4.1 Enthalpy of neutralisation and carbonic acid buffering Quiz: Pearson Edexcel Chemistry, Unit 12

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 12.4.1, Enthalpy of neutralisation and carbonic acid buffering: 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. Standard enthalpy of neutralisation is defined per mole of which substance formed?

    • Salt
    • Water
    • Carbon dioxide
    • Hydrogen ions

  2. What is the typical enthalpy of neutralisation for a strong acid reacting with a strong alkali?

    • About +57 kJ mol-1
    • About -114 kJ mol-1
    • About -10 kJ mol-1
    • About -57 kJ mol-1

  3. Why is the enthalpy of neutralisation for a weak acid less exothermic than a strong acid?

    • Dissociation absorbs energy
    • Products are unstable
    • Water does not form
    • Neutralisation is endothermic

  4. Which species form the main buffer system in human blood?

    • HCO3- and CO32-
    • H2CO3 and CO32-
    • H2SO4 and HSO4-
    • H2CO3 and HCO3-

  5. What is the normal pH range of human blood?

    • About 7.35 to 7.45
    • About 5.00 to 5.50
    • About 6.00 to 6.50
    • About 8.00 to 8.50

  6. What species forms when hydrogencarbonate ions react with added H+ ions in blood?

    • CO32-
    • H2CO3
    • CO2
    • H2O

  7. What products form when carbonic acid decomposes in the lungs?

    • HCO3- and H+
    • CO2 and H2O
    • CO2 and H2
    • CO and H2O

  8. A reaction of 50.0 cm3 of 1.0 mol dm-3 HCl with 50.0 cm3 of 1.0 mol dm-3 NaOH gives a temperature rise of 6.8 C. Using c = 4.18 J g-1 K-1 and 100 g of solution, what is the enthalpy of neutralisation?

    • +57 kJ mol-1
    • -57 kJ mol-1
    • -2.8 kJ mol-1
    • -114 kJ mol-1

  9. If the ratio [HCO3-]/[H2CO3] in blood is 20:1 and the apparent pKa is 6.1, what is the blood pH?

    • 7.00
    • 8.10
    • 6.10
    • 7.40

  10. What happens to blood pH when the [HCO3-]/[H2CO3] ratio decreases?

    • It increases
    • It decreases
    • It doubles
    • It remains unchanged

  11. Why is the enthalpy of neutralisation for weak acids less exothermic than strong acids?

    • Energy breaks bonds
    • Energy ionises acid
    • Energy evaporates water
    • Energy forms solids

  12. What is log10(20) to two decimal places?

    • 0.30
    • 1.30
    • 2.00
    • 1.00

  13. What happens to carbonic acid concentration in blood when CO2 is exhaled?

    • It remains unchanged
    • It increases
    • It fluctuates
    • It decreases

  14. Which condition is caused by an increase in blood pH during hyperventilation?

    • Metabolic acidosis
    • Respiratory alkalosis
    • Renal failure
    • Respiratory acidosis

  15. What ratio [HCO3-]/[H2CO3] gives a blood pH of 7.40, using an apparent pKa of 6.1?

    • 20:1
    • 10:1
    • 1:20
    • 2:1

  16. The enthalpy of neutralisation of a weak acid with NaOH is -55 kJ mol-1, and that of a strong acid is -57 kJ mol-1. What is the implied enthalpy change for dissociating the weak acid?

    • +2 kJ mol-1
    • +55 kJ mol-1
    • -2 kJ mol-1
    • +112 kJ mol-1

  17. What is the ratio of [HCO3-] to [H2CO3] in healthy human blood?

    • 1:20
    • 10:1
    • 20:1
    • 1:1

  18. A 25.0 cm3 sample of 1.00 mol dm-3 HCl is neutralised by excess NaOH. The solution has mass 50.0 g, a temperature rise of 5.0 C and c = 4.18 J g-1 K-1. What is the enthalpy of neutralisation?

    • +41.8 kJ mol-1
    • -4.2 kJ mol-1
    • -41.8 kJ mol-1
    • -83.6 kJ mol-1

  19. Which organ controls hydrogencarbonate ion concentration in human blood?

    • Lungs
    • Kidneys
    • Liver
    • Heart

  20. At what pH value is a buffer solution most effective?

    • Near its pKa
    • At pH 14.0
    • At pH 7.0
    • Near its Ka

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