Target: 10 Questions in 10 minutes

An IB Chemistry data booklet is helpful

1. Which of the following statements is/are true for the electrolysis of molten NaCl vs. the electrolysis of saturated NaCl solution?

I. Sodium is produced at the cathode for both electrolysis.
II. Chlorine is produced at the anode for both electrolysis.
III. In the electrolysis of saturated NaCl solution, the volume ratio of gases produced on the anode to cathode is 1:1.
 
  • A.   II only
  • B.   I and II only
  • C.   I and III only
  • D.   II and III only
2. How many of the aqueous solutions of MgCl2, CuSO4, HNO3, and KOH produce gas on the anode when they are electrolysed using inert graphite electrodes?
  • A.   4
  • B.   3
  • C.   2
  • D.   1

3. In the electrolysis of aqueous calcium fluoride using inert graphite electrodes, what is the correct combination of half-equations at the electrodes?
  Cathode Anode
A. Ca2+(aq) + 2e- → Ca(s) 2F-(aq) → F2(g) + 2e-
B. Ca2+(aq) + 2e- → Ca(s) 2H2O(l)  →  O2(g) + 4H+(aq) + 4e-
C. H2O(l) + e- → H2(g) + OH- (aq) 2H2O(l)  →  O2(g) + 4H+(aq) + 4e-
D. H2O(l) + e- → H2(g) + OH- (aq) 2F-(aq) → F2(g) + 2e-
4. In the electrolysis of dilute sulphuric acid H2SO4 using inert electrodes, which of the following statements is true?
  • A.   Hydrogen gas is produced on the anode.
  • B.   Water is oxidised on the anode.
  • C.   Sulphur dioxide gas is released on the cathode.
  • D.   The solution becomes less acidic as electrolysis proceeds.
5. Which of the following equations describe the overall process in the electrolysis of 1 mol dm-3 potassium bromide solution KBr(aq)?
  • A.   2KBr(aq) → 2K(s) + Br2(g)
  • B.   2H2O(l) → 2H2(g) + O2(g)
  • C.   4KBr(aq) + 2H2O(l) → 4K(s) + O2(g) + 4HBr(aq)
  • D.   2KBr(aq) + 2H2O(l) → 2KOH(aq) + Br2(g) + H2(g)
6. During the electroplating of a metal spoon with silver, which of the following should be used as the anode?
  • A.   The metal spoon
  • B.   A piece of silver
  • C.   A solution of silver nitrate
  • D.   An inert graphite electrode
7. Why is it not advisable to use aluminium electrodes for the electrolysis of water?
  • A.   Aluminium is more likely to be oxidised than water on the anode.
  • B.   Aluminium is covered by a layer of impermeable aluminium oxide.
  • C.   Aluminium is more likely to be reduced than water on the cathode.
  • D.   Aluminium hydroxide is not soluble.

8. A coin is being electroplated with copper. Which of the following statements is/are correct?

I. The coin should be placed on the cathode.
II. Copper carbonate is a suitable electrolyte for the process.
III. The mass of the anode decreases during the electroplating.
  • A.   I and II only
  • B.   I and III only
  • C.   II and III only
  • D.   I, II and III

9. Two electrolytic cells are connected in series as shown in the diagram. The same amount of current flows through the cells for the same amount of time. All the electrodes are made from inert graphite.

2 x electrolytic cells in series

What is the ratio of volumes of gases produced on electrode 1 to electrode 4?
  • A.   4:1
  • B.   2:1
  • C.   1:1
  • D.   1:2

10. Three electrolytic cells are connected in series as shown in the diagram, containing aqueous solutions of AgNO3, CuCl2 and NiSO4.

3 x electrolytic cells in series

Which graphite electrode becomes coated with the highest mass of metals, if the same amount of current flows through the cells for the same amount of time?

  • A.   Electrode 1
  • B.   Electrode 2
  • C.   Electrode 3
  • D.   None of the above