Electrode potentials and cells: AQA A‑Level Chemistry questions

AQA A-Level Chemistry past-paper questions on 3.1.11.1 Electrode potentials and cells, 2008–2025, with mark schemes and examiner’s reports where available.

All 107 questions on Electrode potentials and cells, as a list

June 2025, Paper 1, Q07.4 (2 marks): Table 6 shows some electrode half-equations and their standard electrode potentials. Table 6 Electrode half-equation E o / V VO2+(aq) + 2 H+(aq) + e− → VO2+(aq)
June 2025, Paper 3, Q03.1 (3 marks): Figure 1 shows three mistakes made by the student. Identify each mistake and the change needed to correct it. [3 marks] Mistake 1 Change 1 Mistake 2 Change 2 Mi
June 2025, Paper 3, Q03.2 (1 mark): What feature of the voltmeter ensures that the voltmeter measures the cell EMF? [1 mark] Tick () one box. Low resistance Variable resistance High resistance
June 2025, Paper 3, Q03.3 (1 mark): The Fe3+/Fe2+ electrode is the positive electrode when the cell is set up correctly at 298 K Give the redox equation for the overall reaction that occurs in the
June 2025, Paper 3, Q03.4 (6 marks): Table 4 shows some standard electrode potentials. Table 4 Half-equation E o / V Fe2+(aq) + 2 e– → Fe(s) –0.44 Cu2+(aq) + e– → Cu+(aq) +0.15 Cu2+(aq) + 2 e– → Cu
June 2024, Paper 1, Q06.1 (2 marks): Use the data in Table 3 to explain why Zn reduces an aqueous solution of VO2+ ions to V2+ ions, but does not reduce it any further. [2 marks]
June 2024, Paper 1, Q06.2 (1 mark): Identify the species in Table 3 that can reduce an aqueous solution of VO2+ to V [1 mark]
June 2024, Paper 1, Q06.3 (3 marks): Two half-cells Fe2+(aq) / Fe(s) and VO2+(aq) / V3+(aq) are connected. Calculate the EMF of this cell. Give the conventional representation for this cell. Give a
June 2024, Paper 3, Q17 (1 mark): A cell with EMF = +2.15 V is made from two electrodes. The half-equations for the two electrodes are shown. positive electrode: PbO2(s) + 3 H+(aq) + HSO4–(aq) +
June 2023, Paper 1, Q02.1 (2 marks): State the purpose of the salt bridge. Identify an ionic compound that could be used in the salt bridge. [2 marks] Purpose Identity
June 2023, Paper 1, Q02.2 (1 mark): State how, if at all, the EMF of this cell will change if the surface area of the platinum electrode is increased. [1 mark]
June 2023, Paper 1, Q02.3 (1 mark): Water is added to the beaker containing the magnesium chloride solution. What is the effect on the magnitude of the EMF of the cell? [1 mark] Tick () one box.
June 2023, Paper 1, Q02.4 (1 mark): The voltmeter V shown in Figure 1 is replaced by a bulb. Give an equation for the overall reaction that occurs when the cell is operating. [1 mark]
June 2022, Paper 1, Q08.1 (1 mark): The half-equations for two electrodes that combine to make a non-rechargeable cell are Zn2+(aq) + 2e− → Zn(s) E o = −0.76 V 2 MnO2(s) + 2 NH4+(aq) + 2e– → Mn2O3
June 2022, Paper 3, Q11 (1 mark): Which change to a hydrogen electrode has no effect on the electrode potential? [1 mark] A the concentration of the hydrogen ions B the pressure of the hydrogen
June 2022, Paper 3, Q12 (1 mark): Some electrode potential data are shown. Zn2+(aq) + 2 e− → Zn(s) E ɵ = − 0.76 V Pb2+(aq) + 2 e− → Pb(s) E ɵ = − 0.13 V Which is a correct statement about this c
November 2021, Paper 1, Q08.1 (1 mark): State the meaning of the term electrochemical series. [1 mark]
November 2021, Paper 1, Q08.2 (1 mark): State two conditions needed for the following half-cell to have E o = 0.00 V H+(aq) + e– → 1 2 H2(g) [1 mark]
November 2021, Paper 1, Q08.3 (1 mark): Identify the weakest reducing agent in Table 8. [1 mark]
November 2021, Paper 1, Q08.4 (2 marks): Use half-equations from Table 8 to deduce an equation for the reduction of VO2+ to form VO2+ in aqueous solution by iron. [2 marks]
November 2021, Paper 1, Q08.5 (2 marks): Use data from Table 8 to explain why [Co(H2O)6]3+(aq) will undergo a redox reaction with [Fe(H2O)6]2+(aq) Give an equation for this reaction. [2 marks] Explanat
November 2021, Paper 1, Q08.6 (1 mark): Suggest why the two cobalt(III) complex ions in Table 8 have different electrode potentials. [1 mark]
November 2021, Paper 1, Q09.1 (2 marks): Use data in Table 9 to explain why an aqueous electrolyte is not used for a lithium cell. [2 marks]
November 2021, Paper 1, Q09.2 (1 mark): In the 1970s lithium-iodine cells became a common power source for heart pacemakers. Lithium iodide is the final product of the cell reaction. Use the data in T
November 2021, Paper 1, Q09.3 (1 mark): An EMF value for a commercial lithium-iodine cell is 2.80 V Suggest why this value is different from the value calculated in Question 09.2. [1 mark]
November 2020, Paper 1, Q11.4 (2 marks): The negative electrode is made of carbon and the positive electrode is made of platinum. Give the conventional representation for the glucose–oxygen fuel cell.
November 2020, Paper 3, Q06.1 (3 marks): State the substances and conditions needed in a standard hydrogen electrode. [3 marks]
November 2020, Paper 3, Q06.2 (6 marks): Describe an experiment the student does to show that the standard electrode potential for the TiO2+(aq) / Ti(s) electrode is −0.88 V The student is provided wit
November 2020, Paper 3, Q06.3 (1 mark): Give the half-equation for the electrode reaction in the TiO2+(aq) / Ti(s) electrode in acidic conditions. [1 mark]
November 2020, Paper 3, Q06.4 (3 marks): Table 2 shows some electrode potential data. Table 2 Electrode reaction Eo / V 2 H+(aq) + 2 e− → H2(g) 0.00 Cu2+(aq) + 2 e− → Cu(s) +0.34 NO3−(aq) + 4 H+(aq) +
June 2019, Paper 3, Q03.1 (1 mark): Name the piece of apparatus labelled A. [1 mark]
June 2019, Paper 3, Q03.2 (1 mark): State the purpose of A. [1 mark]
June 2019, Paper 3, Q03.3 (1 mark): Name the substance used as electrode B in Figure 1. [1 mark]
June 2019, Paper 3, Q03.4 (4 marks): Complete Table 1 to identify C, D and E from Figure 1. Include the essential conditions for each. [4 marks] Table 1 Identity Conditions C D E
June 2019, Paper 3, Q03.5 (2 marks): The standard electrode potential, Eo, for the Fe3+/Fe2+ electrode is +0.77 V Give the ionic equation for the overall reaction in the cell in Figure 1. State the
June 2019, Paper 3, Q03.6 (3 marks): A student sets up a cell as shown in the cell representation. Zn(s)|Zn2+(aq)||Cu2+(aq)|Cu(s) The student measures the cell EMF, Ecell, with several different co
June 2019, Paper 3, Q03.7 (3 marks): This equation shows how Ecell varies with concentration for this reaction. This equation is in the form of the equation for a straight line, y = mx + c Calculat
June 2019, Paper 3, Q03.8 (2 marks): In experiment 2 in Table 2 the electrode potential of the Cu2+/Cu electrode is +0.33 V Use data from Table 2 in question 03.6 to calculate the electrode potenti
June 2019, Paper 3, Q13 (1 mark): The Eo values for two electrodes are shown. Fe2+(aq) + 2 e– → Fe(s) Eo= –0.44 V Cu2+(aq) + 2 e– → Cu(s) Eo= +0.34 V What is the EMF of the cell Fe(s)|Fe2+(aq)||
June 2018, Paper 1, Q06.1 (1 mark): Explain how the salt bridge provides an electrical connection between the two solutions. [1 mark]
June 2018, Paper 1, Q06.2 (1 mark): The standard electrode potential for the Cu2+/Cu electrode is Cu2+(aq) + 2e– → Cu(s) Eo = + 0.34 V Calculate the electrode potential of the left-hand electrode
June 2018, Paper 1, Q06.3 (1 mark): Both electrodes contain a strip of copper metal in a solution of aqueous Cu2+ ions. State why the left-hand electrode does not have an electrode potential of +0
June 2018, Paper 1, Q06.4 (1 mark): Give the conventional representation for the cell in Figure 2. Include all state symbols. [1 mark]
June 2018, Paper 1, Q06.5 (2 marks): When the voltmeter is replaced by a bulb, the EMF of the cell in Figure 2 decreases over time to 0 V Suggest how the concentration of copper(II) ions in the lef
June 2018, Paper 1, Q09.1 (2 marks): Use data from Table 4 to identify the species that can be used to reduce VO2 + ions to VO2+ in aqueous solution and no further. Explain your answer. Table 4 Ele
June 2017, Paper 1, Q10.2 (1 mark): State the weakest reducing agent in Table 4. [1 mark]
June 2017, Paper 1, Q10.3 (2 marks): Write the conventional representation of the cell that has an EMF of +0.43 V [2 marks]
June 2017, Paper 1, Q10.4 (4 marks): Use data from Table 4 to identify an acid that will oxidise copper. Explain your choice of acid. Use these data to suggest a possible equation for the reaction.
Specimen, Paper 1, Q03.1 (2 marks): 3 Fuel cells are an increasingly important energy source for vehicles. Standard electrode potentials are used in understanding some familiar chemical reactions
Specimen, Paper 1, Q03.2 (1 mark): Use data from Table 1 to deduce the halide ion that is the weakest reducing agent. [1 mark] 0 3 . 2
Specimen, Paper 1, Q03.3 (1 mark): Use data from Table 1 to justify why sulfate ions should not be capable of oxidising bromide ions. [1 mark] 0 3 . 3
Specimen, Paper 1, Q03.4 (1 mark): EMF = V
Specimen, Paper 3, Q18 (1 mark): The following cell has an EMF of +0.46 V. Cu Cu2+ Ag+ Ag Which statement is correct about the operation of the cell? [1 mark] A Metallic copper is oxidised by A
June 2016, CHEM5 (old spec), Q4(a)(i) (1 mark): Identify the weakest oxidising agent in Table 2. [1 mark]
June 2016, CHEM5 (old spec), Q4(a)(ii) (2 marks): Give the conditions under which the electrode potential of the Zn2+/Zn electrode is –0.76 V. [2 marks]
June 2016, CHEM5 (old spec), Q4(b) (3 marks): Two half-cells, involving species in Table 2, are connected together to give a cell with an e.m.f. = +0.48 V. Use data from Table 2 to deduce the conventional r
June 2016, CHEM5 (old spec), Q4(c) (3 marks): Use data from Table 2 to identify a cobalt species that can react with water. Write an equation for the redox reaction that occurs and identify the oxidation pr
June 2016, CHEM5 (old spec), Q4(d) (2 marks): Use data from Table 2 to explain why gold jewellery is unreactive in moist air. [2 marks]
June 2016, CHEM5 (old spec), Q5(a)(ii) (2 marks): State and explain the effect, if any, of increasing the pressure of oxygen on the e.m.f of this cell. [2 marks] Effect on e.m.f. Explanation
June 2015, CHEM5 (old spec), Q6(b) (2 marks): Identify the weakest oxidising agent in Table 6. Explain your choice. [2 marks] Weakest oxidising agent Explanation
June 2015, CHEM5 (old spec), Q6(c) (4 marks): Write the conventional representation of the cell used to measure the standard electrode potential for the Ag+/Ag electrode. State the conditions necessary when
June 2015, CHEM5 (old spec), Q6(d) (4 marks): Use data from Table 6 to explain, in terms of redox, what happens when a soluble gold(I) compound containing Au+ ions is added to water. State what you would ob
June 2015, CHEM5 (old spec), Q6(e)(i) (1 mark): Calculate the e.m.f. of this cell. [1 mark] Answer =
June 2015, CHEM5 (old spec), Q6(e)(ii) (1 mark): Suggest why potassium chloride would not be suitable for use in the salt bridge of this cell. [1 mark]
June 2015, CHEM5 (old spec), Q6(f) (2 marks): Use data from Table 6 to explain what happens when a solution of iron(II) chloride is exposed to the air. [2 marks]
June 2014, CHEM5 (old spec), Q5(a) (2 marks): Give the conventional representation of the cell that is used to measure the standard electrode potential of iron as shown in Table 3. [2 marks]
June 2014, CHEM5 (old spec), Q5(c) (2 marks): Identify the weakest reducing agent from the species in Table 3. Explain how you deduced your answer. [2 marks] Species Explanation
June 2014, CHEM5 (old spec), Q5(e) (2 marks): Using the information given in Table 3, deduce an equation for the redox reaction that would occur when hydroxide ions are added to HOCl [2 marks] Question 5 co
June 2014, CHEM5 (old spec), Q5(f)(i) (1 mark): Use data from Table 3 to calculate the e.m.f. of this cell. [1 mark] Answer =
June 2014, CHEM5 (old spec), Q5(f)(ii) (1 mark): Use half-equations from Table 3 to construct an overall equation for the cell reaction. [1 mark]
June 2014, CHEM5 (old spec), Q5(f)(iii) (2 marks): Identify which of A or B, in Figure 1, is the positive electrode. Give a reason for your answer. [2 marks] Positive electrode Reason
June 2013, CHEM5 (old spec), Q5(a) (1 mark): Explain how the salt bridge D provides an electrical connection between the two electrodes. (1 mark)
June 2013, CHEM5 (old spec), Q5(b) (1 mark): Suggest why potassium chloride would not be a suitable salt for the salt bridge in this cell. (1 mark)
June 2013, CHEM5 (old spec), Q5(c) (2 marks): In the external circuit of this cell, the electrons flow through the ammeter from right to left. Suggest why the electrons move in this direction.
June 2013, CHEM5 (old spec), Q5(d) (1 mark): Explain why the current in the external circuit of this cell falls to zero after the cell has operated for some time. (1 mark)
June 2013, CHEM5 (old spec), Q5(e)(i) (1 mark): The e.m.f. of this cell is 2.90 V. Use this information to calculate a value for the electrode potential of electrode B. (1 mark)
January 2013, CHEM5 (old spec), Q7(a) (5 marks): Draw a labelled diagram of the apparatus that could be connected to a standard hydrogen electrode in order to measure the standard electrode potential of the Fe
January 2013, CHEM5 (old spec), Q7(b) (4 marks): Use data from the table to deduce the equation for the overall cell reaction of a cell that has an e.m.f. of 0.78 V. Give the conventional cell representation f
January 2013, CHEM5 (old spec), Q7(c) (3 marks): Use data from the table to explain why Au+ ions are not normally found in aqueous solution. Write an equation to show how Au+ ions would react with water.
January 2013, CHEM5 (old spec), Q7(d) (3 marks): Use data from the table to predict and explain the redox reactions that occur when iron powder is added to an excess of aqueous silver nitrate.
June 2012, CHEM5 (old spec), Q5(b) (2 marks): Deduce the identity of the weakest oxidising agent in the table. Explain how E values can be used to make this deduction. Weakest oxidising agent Explanation (2
June 2012, CHEM5 (old spec), Q5(c)(i) (1 mark): Calculate the e.m.f. of this cell. (1 mark)
June 2012, CHEM5 (old spec), Q5(e)(iii) (1 mark): The e.m.f. of an ethanol–oxygen fuel cell is 1.00 V. Use data from the table on page 10 to calculate a value for the electrode potential of the ethanol electrod
June 2012, CHEM5 (old spec), Q7(d) (7 marks): The chromium(II) ion [Cr(H2O)6]2+ has different properties from the [Cr(H2O)6]3+ ion. Use data from the table on page 16 to explain why, in an open container, [
January 2012, CHEM5 (old spec), Q4(a) (3 marks): Identify solution A and give its concentration. State the other essential conditions for the operation of the standard electrode that forms the left-hand side o
January 2012, CHEM5 (old spec), Q4(b) (3 marks): Identify the material from which electrodes B are made. Give two reasons why this material is suitable for its purpose. Material Reason 1 Reason 2
January 2012, CHEM5 (old spec), Q4(c) (3 marks): Identify a solution that could be used in C to complete the circuit. Give two reasons why this solution is suitable for its purpose. Solution Reason 1 Reason 2
January 2012, CHEM5 (old spec), Q4(d) (1 mark): Write the conventional representation for this cell. (1 mark)
January 2012, CHEM5 (old spec), Q4(e)(i) (1 mark): Write an equation for the overall cell reaction that would occur. (1 mark)
January 2012, CHEM5 (old spec), Q4(e)(ii) (1 mark): Explain why the ammeter reading would fall to zero after a time. (1 mark)
January 2012, CHEM5 (old spec), Q5(a) (1 mark): Identify the most powerful reducing agent from all the species in the table. (1 mark)
January 2012, CHEM5 (old spec), Q5(b) (2 marks): Use data from the table to explain why chlorine should undergo a redox reaction with water. Write an equation for this reaction. Explanation Equation
January 2012, CHEM5 (old spec), Q5(c) (1 mark): Suggest one reason why the redox reaction between chlorine and water does not normally occur in the absence of light. (1 mark)
January 2012, CHEM5 (old spec), Q5(e) (2 marks): Use data from the table to explain why one molecule of hydrogen peroxide can oxidise another molecule of hydrogen peroxide. Write an equation for the redox reac
June 2011, CHEM5 (old spec), Q5(b) (2 marks): Use the table above to identify the strongest reducing agent from the species in the table. Explain how you deduced your answer. Strongest reducing agent Explan
June 2011, CHEM5 (old spec), Q5(c) (3 marks): Use data from the table to explain why fluorine reacts with water. Write an equation for the reaction that occurs. Explanation Equation
June 2011, CHEM5 (old spec), Q5(d)(i) (2 marks): Give the conventional representation for this cell. (2 marks)
June 2011, CHEM5 (old spec), Q5(d)(ii) (1 mark): Calculate the e.m.f. of the cell. (1 mark)
January 2011, CHEM5 (old spec), Q5(b)(i) (2 marks): Write the conventional representation for the cell using platinum contacts. (2 marks)
January 2011, CHEM5 (old spec), Q5(b)(ii) (3 marks): Write an overall equation for the cell reaction and identify the oxidising and reducing agents. Overall equation Oxidising agent
June 2010, CHEM5 (old spec), Q7(a) (4 marks): Describe a standard hydrogen electrode.
June 2010, CHEM5 (old spec), Q7(b) (2 marks): A conventional representation of a lithium cell is given below. This cell has an e.m.f. of +2.91 V Li(s) | Li+(aq) || Li+(aq) | MnO2(s) , LiMnO2(s) | Pt(s) Writ
June 2010, CHEM5 (old spec), Q7(c) (2 marks): Suggest what reactions occur, if any, when hydrogen gas is bubbled into a solution containing a mixture of iron(II) and iron(III) ions. Explain your answer.
January 2010, CHEM5 (old spec), Q3(a) (1 mark): State why the electrode potential for the standard hydrogen electrode is equal to 0.00V. (1 mark)
January 2010, CHEM5 (old spec), Q3(c) (2 marks): Write the conventional representation for an alkaline hydrogen–oxygen fuel cell. (2 marks)
June 2008, CHM5 (2008 spec), Q4(a) (6 marks): 4 (a) The cell shown below can be used to measure the electrode potential of magnesium. V X W Hydrogen Z Y 4 (a) (i) Identify possible chemical substances for W
June 2008, CHM6W (2008 spec), Q20 (1 mark): 20 Consider the half-equations given below. E /V VO+ 2(aq) + 2H+(aq) + e– →VO2+(aq) + H2O(l) +1.00 Cr2O2 7 –(aq) + 14H+(aq) + 6e– →2Cr3+(aq) + 7H2O(l) +1.33 Co3

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