Lesson 14.1.1

14.1.1 Standard electrode potentials and the hydrogen electrode Quiz: Pearson Edexcel Chemistry, Unit 14

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 14.1.1, Standard electrode potentials and the hydrogen electrode: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 14: Redox II, written with Revision Ninja.

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The 20 questions

  1. What is the standard hydrogen electrode?

    • Hydrogen gas at 100 kPa over copper in pure water, assigned E = 0.00 V
    • Hydrogen gas at 1.00 mol dm-3 pressure over platinum at 373 K
    • Oxygen gas at 100 kPa over zinc at 298 K, assigned E = 0.00 V
    • Hydrogen gas at 100 kPa over platinum in 1.00 mol dm-3 H+ solution at 298 K, assigned E = 0.00 V

  2. Why is a reference electrode necessary when measuring standard electrode potentials?

    • Electrode potentials are always measured against a calcium electrode
    • The hydrogen electrode is the only electrode that generates electricity
    • Reference electrodes change the pH of the solution being measured
    • Absolute electrode potentials cannot be measured

  3. Which conditions define a standard electrode potential?

    • 373 K, 100 kPa and 2.00 mol dm-3
    • 298 K, 100 kPa for gases
    • 273 K, 101.3 kPa and 0.10 mol dm-3
    • 298 K, 50 kPa and 0.50 mol dm-3

  4. What is the standard electrode potential, E-zero, of a half-cell?

    • The potential difference between two identical half-cells connected through a salt bridge at 298 K
    • The electrode potential measured under standard conditions relative to the standard hydrogen electrode
    • The voltage of a cell when all ion concentrations are set to zero, which is the basis of the E-zero value
    • The potential of the electrode measured at its melting temperature, when the metal changes phase

  5. What does a more negative standard electrode potential indicate?

    • The electrode is in equilibrium with hydrogen gas at 298 K
    • The ion is a stronger oxidising agent than the more positive species
    • The reduced form is a stronger reducing agent, and the ion is a weaker oxidising agent
    • The reaction is faster than the one at the standard hydrogen electrode

  6. Which metal is the strongest reducing agent among magnesium (E-zero -2.37 V), zinc (-0.76 V) and copper (+0.34 V)?

    • Copper, because it has the most positive standard electrode potential
    • Magnesium, because it has the most negative standard electrode potential
    • Silver, because it is the least reactive of the four
    • Zinc, because it lies between the other two metals

  7. What is the standard electrode potential of the standard hydrogen electrode?

    • -0.76 V, the Zn2+/Zn value
    • 0.00 V, by definition
    • +1.00 V, a concentration reference
    • +0.34 V, the Cu2+/Cu value

  8. What is the standard cell emf for a Zn/Zn2+ half-cell (E-zero -0.76 V) connected to a Cu2+/Cu half-cell (E-zero +0.34 V), with Cu2+ reduced?

    • +0.42 V
    • +1.10 V
    • +0.76 V
    • -1.10 V

  9. Will chlorine oxidise Fe2+ to Fe3+ under standard conditions? (E-zero Cl2/Cl- = +1.36 V, Fe3+/Fe2+ = +0.77 V)

    • Yes, because E-zero cell = +0.59 V, which is positive
    • Yes, because E-zero cell = +2.13 V
    • No, because E-zero cell = -0.59 V
    • No, because both E-zero values are positive

  10. Which cell diagram corresponds to the cell formed from Zn2+/Zn and Cu2+/Cu with Zn as the negative electrode?

    • Zn(s) | Zn2+(aq) || Cu2+(aq) | Cu(s)
    • Zn2+(aq) | Zn(s) || Cu(s) | Cu2+(aq)
    • Cu(s) | Cu2+(aq) || Zn2+(aq) | Zn(s)
    • Zn(s) | Cu2+(aq) || Zn2+(aq) | Cu(s)

  11. Using E-zero Mg2+/Mg = -2.37 V and Ag+/Ag = +0.80 V, what is the standard emf of Mg + 2Ag+ gives Mg2+ + 2Ag?

    • -1.57 V
    • +3.17 V
    • -3.17 V
    • +1.57 V

  12. Why might a reaction with a positive E-zero cell not be observed in practice?

    • Kinetic inhibition, because the activation energy is high and the reaction is slow
    • The reaction is endothermic, so E-zero must be negative for reactions to occur
    • A positive E-zero means the reaction produces hydrogen gas
    • E-zero values are only valid at 0 K, so measured reactions are always different

  13. How does increasing the concentration of Zn2+ ions affect the electrode potential of the Zn2+/Zn half-cell?

    • It makes the electrode potential more positive, since the ion is more likely to be reduced
    • It has no effect, because only standard electrode potentials matter
    • It makes the potential zero, because the concentration cancels out
    • It makes the potential more negative, since more ions are available to be oxidised

  14. E-zero for Fe2+/Fe is -0.44 V. Which metal will displace iron from an aqueous Fe2+ solution?

    • Lead, since Pb2+/Pb (-0.13 V) is more negative than Fe2+/Fe
    • Copper, since Cu2+/Cu (+0.34 V) is more negative than Fe2+/Fe
    • Silver, since Ag+/Ag (+0.80 V) is more negative than Fe2+/Fe
    • Zinc, since Zn2+/Zn (-0.76 V) is more negative than Fe2+/Fe (-0.44 V)

  15. What is the standard emf of a Zn/Zn2+ half-cell (E-zero -0.76 V) connected to Ag+/Ag (E-zero +0.80 V)?

    • +1.56 V
    • +0.04 V
    • +0.76 V
    • -1.56 V

  16. Why is platinum used in the standard hydrogen electrode?

    • Platinum is inert and provides a surface for the H2/H+ equilibrium without taking part in the reaction
    • Platinum keeps the hydrogen pressure at exactly zero, so that no gas is present at the electrode surface
    • Platinum reacts with hydrogen gas to give a solid platinum hydride electrode with a fixed potential
    • Platinum is the only metal that can form H+ ions in aqueous solution, so it is the only reference choice

  17. Sn2+/Sn has E-zero -0.14 V and Pb2+/Pb has E-zero -0.13 V. Which statement about the cell Sn | Sn2+ || Pb2+ | Pb is correct?

    • E-zero cell = 0.00 V, so no electron transfer occurs
    • E-zero cell = -0.27 V, so the reaction is not feasible
    • E-zero cell = +0.27 V, so the reaction is strongly feasible
    • E-zero cell = +0.01 V, so the cell is feasible but its emf is very small

  18. A student uses a standard half-cell at 0.10 mol dm-3 rather than 1.00 mol dm-3 and measures a different potential. What is the best explanation?

    • The standard hydrogen electrode changes its potential with the concentration of platinum
    • E-zero depends only on temperature, not on concentration
    • Concentration does not affect any electrode potential
    • Electrode potential depends on ion concentration

  19. Why are standard electrode potentials written as reduction half-equations?

    • Because reduction always occurs at the anode, so the reduction potentials are measured at the negative terminal
    • Because oxidation potentials are defined as zero, which makes the reduction values relative to the anode
    • Because all E-zero values are positive by definition, so that cell emfs are always quoted as positive numbers
    • By convention, so all values can be combined consistently in cell calculations

  20. What is the standard emf for Mg (anode, E-zero -2.37 V) and Zn2+/Zn (cathode, -0.76 V) with the magnesium oxidised?

    • +1.61 V
    • +3.13 V
    • -1.61 V
    • +0.61 V

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