Electrochemistry: past paper questions
Real questions on electrochemistry
The newest 20 of 139 written questions. Open one to see it on the real paper.
- 9701/41 · May/June 2026 · Q4b[2]
An electrochemical cell is set up using a V 3+ / V 2+ electrode and a Cu 2+ / Cu electrode, both under standard conditions. Write an equation for the cell reaction that occurs and calculate the value for E ⦵ cell . equation E = V
See it on the paper → - 9701/41 · May/June 2026 · Q4c[2]
Identify two atoms or ions from Table 4.1 that will reduce Fe 3+ to Fe 2+ under neutral conditions, but will not reduce Fe(OH) 3 to Fe(OH) 2 under alkaline conditions. and
See it on the paper → - 9701/41 · May/June 2026 · Q4e[3]
A dilute solution of NaOH(aq) is electrolysed using inert electrodes. A steady current of 2.40 A is passed for 2.00 hours. Calculate the mass, in g, of oxygen that is released at the anode. mass of oxygen = g
See it on the paper → - 9701/41 · October/November 2025 · Q2c(ii)[3]
[Fe(H 2 O) 4 (OH) 2 ] is a green precipitate that turns brown on standing in air. Table 2.1 shows electrode potentials for some electrode reactions. Table 2.1 E o / V electrode reaction Fe(H 2 O) 3 (OH) 3 + H 2 O + e – Fe(H 2 O) 4 (OH) 2 + OH – O 2 + 2H 2 O + 4e – 4OH – –0.56 +0.40 Use the information in Table 2.1 to e...
See it on the paper → - 9701/41 · October/November 2025 · Q2d[2]
The complex [Co(NH 3 ) 6 ] 2+ reacts with hydrogen peroxide as shown. reaction 1 2[Co(NH 3 ) 6 ] 2+ + H 2 O 2 2[Co(NH 3 ) 6 ] 3+ + 2OH – o E cell = +1.67 V Calculate ΔG o , in kJ mol –1 , for reaction 1. ΔG o = kJ mol –1
See it on the paper → - 9701/41 · October/November 2025 · Q4a[2]
o (a) Define standard cell potential, E cell . Include a description of standard conditions.
See it on the paper → - 9701/41 · October/November 2025 · Q4b(i)[3]
Draw a labelled diagram of this electrochemical cell. Include all necessary substances and relevant pieces of apparatus needed to measure o . the E cell It is not necessary to state the conditions used.
See it on the paper → - 9701/41 · October/November 2025 · Q4b(ii)[1]
State the charge carriers that transfer current through the solutions and through the wire. the solutions the wire
See it on the paper → - 9701/41 · October/November 2025 · Q4b(iii)[2]
The standard electrode potential, E o , for the Zn 2+ (aq) / Zn(s) electrode is –0.76 V. Water is added to a standard Zn 2+ (aq) / Zn(s) electrode. The new concentration of Zn 2+ (aq) is 0.25 mol dm –3 . Use the Nernst equation to calculate the electrode potential, E, for this new Zn 2+ (aq) / Zn(s) electrode. ĬÙĊ¾Ġ´íÈ...
See it on the paper → - 9701/41 · October/November 2025 · Q4c(i)[1]
Use this information to determine the change in oxidation state of manganese when this cell is discharging. from to
See it on the paper → - 9701/41 · October/November 2025 · Q4c(ii)[1]
Write the equation for the overall reaction that occurs when this cell is discharging.
See it on the paper → - 9701/41 · October/November 2025 · Q4c(iii)[1]
The E o for the ZnO / Zn electrode is –1.28 V. Calculate the standard electrode potential, E o , for the MnO 2 / Mn 2 O 3 electrode. E o (MnO 2 / Mn 2 O 3 ) = V
See it on the paper → - 9701/43 · October/November 2025 · Q1e(i)[2]
Write the expression for the solubility product, K sp , of Hg 2 F 2 . Include the units. K sp =
See it on the paper → - 9701/43 · October/November 2025 · Q1e(ii)[1]
The solubility of Hg 2 F 2 is 9.20 × 10 –3 mol dm –3 at 298 K. Calculate the value of K sp of Hg 2 F 2 at 298 K. K sp =
See it on the paper → - 9701/43 · October/November 2025 · Q2c(ii)[3]
[Fe(H 2 O) 4 (OH) 2 ] is a green precipitate that turns brown on standing in air. Table 2.1 shows electrode potentials for some electrode reactions. Table 2.1 E o / V electrode reaction Fe(H 2 O) 3 (OH) 3 + H 2 O + e – Fe(H 2 O) 4 (OH) 2 + OH – O 2 + 2H 2 O + 4e – 4OH – –0.56 +0.40 Use the information in Table 2.1 to e...
See it on the paper → - 9701/43 · October/November 2025 · Q2d[2]
The complex [Co(NH 3 ) 6 ] 2+ reacts with hydrogen peroxide as shown. reaction 1 2[Co(NH 3 ) 6 ] 2+ + H 2 O 2 2[Co(NH 3 ) 6 ] 3+ + 2OH – o E cell = +1.67 V Calculate ΔG o , in kJ mol –1 , for reaction 1. ΔG o = kJ mol –1
See it on the paper → - 9701/43 · October/November 2025 · Q4a[2]
o (a) Define standard cell potential, E cell . Include a description of standard conditions.
See it on the paper → - 9701/43 · October/November 2025 · Q4b(i)[3]
Draw a labelled diagram of this electrochemical cell. Include all necessary substances and relevant pieces of apparatus needed to measure o . the E cell It is not necessary to state the conditions used.
See it on the paper → - 9701/43 · October/November 2025 · Q4b(ii)[1]
State the charge carriers that transfer current through the solutions and through the wire. the solutions the wire
See it on the paper → - 9701/43 · October/November 2025 · Q4b(iii)[2]
The standard electrode potential, E o , for the Zn 2+ (aq) / Zn(s) electrode is –0.76 V. Water is added to a standard Zn 2+ (aq) / Zn(s) electrode. The new concentration of Zn 2+ (aq) is 0.25 mol dm –3 . Use the Nernst equation to calculate the electrode potential, E, for this new Zn 2+ (aq) / Zn(s) electrode. ĬÙĊ¾Ġ´íÈ...
See it on the paper →
What examiners said
Most candidates identified H2O2 as the positive half-cell but some incorrectly gave +1.77 V or +1.36 V.
— Examiner report, October/November 2023, 9701/41 Q3(e)(i) (Cambridge)
This question was well answered. Common errors included +421 (sign error) and –341.6 (use of 1.77 instead of 2.18 for the Ecell).
— Examiner report, October/November 2023, 9701/41 Q3(e)(ii) (Cambridge)
This question was found to be difficult. Many incorrect versions of the Nernst equation were seen. Some common errors were +1.94 and +1.76.
— Examiner report, October/November 2023, 9701/41 Q3(f)(i) (Cambridge)
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