9. Redox Processes HL

1.Aqueous solutions of AgNO3, Cu(NO3)2 and Cr(NO3)3 are electrolyzed using the same quantity of electricity. How do the number of moles of metal formed compare?

2. The standard electrode potentials for two half-cells involving iron are given below. Fe2+(aq) + 2e– → Fe(s)    Eο = –0.44 V Fe3+(aq) + e–→ Fe2+(aq)     Eο = +0.77 V What is the equation and the cell potential for the spontaneous reaction that occurs when the two half-cells are connected?

3. Metallic tin can be produced by the electrolysis of a molten salt containing Sn2+ ions. Which change(s) would double the amount of tin produced? I. Doubling the current passed during electrolysis II. Doubling the time used for electrolysis III.    Using Sn4+ ions instead of Sn2+ ions

4. Which of the following factors affect the amount of product formed during electrolysis? I. The current used II. The duration of electrolysis III.    The charge on the ion

5. The cyanide ion, CN–, can form two complex ions with iron ions. The formulas of these ions are [Fe(CN)6]4– and [Fe(CN)6]3–. What is the oxidation number of iron in the two complex ions?

	[Fe(CN)6]4–	[Fe(CN)6]3–
A.	–4	–3
B.	+2	+3
C.	+3	+2
D.	–3	–4

6. Consider the following reactions. Cu2+(aq) + 2e–  Cu(s)     Eο = +0.34 V Mg2+(aq) + 2e–  Mg(s)     Eο = –2.36 V Zn2+(aq) + 2e–  Zn(s)     Eο = –0.76 V Which statement is correct?

7. Consider the standard electrode potentials of the following reactions. Cr3+(aq) + 3e– →Cr(s)     –0.75 V Cd2+(aq) + 2e– → Cd(s)     –0.40 V What is the value of the cell potential (in V) for the following reaction? 2Cr(s) + 3Cd2+(aq) → 2Cr3+(aq) + 3Cd(s)

8. Aqueous solutions containing different concentrations of NaCl were electrolysed using platinum electrodes. What is the major product at the positive electrode in each case?

	0.001 mol dm–3 NaCl(aq)	1.0 mol dm–3 NaCl(aq)
A.	H2	Na
B.	H2	H2
C.	O2	Cl2
D.	Cl2	O2

9. Which is a feature of the standard hydrogen electrode?

10. Which pair of factors both affect the amount (in mol) of chlorine produced in the electrolysis of aqueous sodium chloride?

11. From the given standard electrode potentials which statement is correct? Ca2+(aq) + 2e–  Ca(s)    EӨ = –2.87 V Ni2+(aq) + 2e–  Ni(s)    EӨ = –0.23 V Fe3+(aq) + e–  Fe2+(aq)    EӨ = +0.77 V

12. Which statement is correct about the electrolysis of copper(II) sulfate solution using graphite electrodes?

13. A metallic object is electroplated with copper using a solution of copper(II) sulfate. Which statement is correct?

14. Two half-equations and their standard electrode potentials are shown in the table.

Half-equation	EӨ / V
Pb2+(aq) + 2e–  Pb(s)	–0.13
Ag2+(aq) + e–  Ag(s)	+0.80

What is the cell potential, in V, for the reaction below? Pb(s) + 2Ag+(aq) → Pb2+(aq) + 2Ag(s)

15. Two electrolytic cells are connected in series so that the same current flows through both cells for the same length of time.   The amount of tin deposited is 0.01 mol. How much copper is deposited?

16. Which are used for the electroplating of a metal spoon with copper? I. an electrolyte containing aqueous copper(II) ions II. a copper anode (positive electrode) III.    a copper cathode (negative electrode)

17. Consider these standard electrode potentials. Cu2+(aq) + e– → Cu+(aq)    EӨ = +0.15 V Cu+(aq) + e– → Cu(s)    EӨ = +0.52 V What is the standard cell potential when the two half-cells are connected?

18. Consider the standard electrode potentials of the following reactions: Sn4+(aq) + 2e– → Sn2+(aq)    +0.15 V Fe3+(aq) + e– → Fe2+(aq)    +0.77 V What is the value of the cell potential (in volts) for the spontaneous reaction?

19. In the electrolysis of acidified water, if 8.4 cm3 of hydrogen gas is evolved, what volume of oxygen gas is evolved?

20. Which factors affect the amount of metal formed during electrolysis? I. Charge on the metal ion II. Current III.    Time

21. Which changes lead to the production of more moles of metal during the electrolysis of a molten salt? I. using a metal ion with a higher charge II. increasing the current III.    using a longer time

22. Which equation represents the reduction process occurring in the standard hydrogen electrode?

23. Which statement is correct about the value of Eο?