ELECTROLYSIS
1. Fig. 1.1 shows an incomplete set-up used in the laboratory to decompose water by
electrolysis
(a) Complete Fig. 1.1, by drawing in the cell symbol. [1]
(b) Explain why the water is acidified during electrolysis.
© Describe the reaction that occurs at the cathode.
d) State the importance of using platinum electrodes in Fig. 1.1
2. Fig. 2.1 shows the electrolytic cell used to extract aluminium from its ore
(a) Suggest the name of waste gas C
(b) Name the aluminium ore
(c) Explain why aluminium is extracted using electrolysis rather than reduction by carbon
(d) Explain why aluminium is used in the manufacture of food containers.
3. Molten copper(II) chloride and aqueous copper(II) chloride can both be decomposed via
electrolysis
Identify the ions in molten copper(II) chloride and aqueous copper(II) chloride.
molten copper(II) chloride…………………………………………………………….
aqueous copper(II) chloride…………………………………………………
4. A student sets up the apparatus to carry out the electrolysis of concentrated sodium
chloride solution using carbon electrodes as shown in Fig. 4.1.
(a) Name all the positive ions present in aqueous sodium chloride
(b) Name gases C and D
(c) Explain why the solution formed is alkaline
5. Fig. 5.1 shows apparatus used to electroplate an iron nail with copper metal.
a) Name the cathode in Fig. 5.1.
b) The reaction that occurs at one of the electrodes is represented by the following
equation:
Explain oxidation using this equation
6. Copper is extracted from molten copper(II) chloride by electrolysis as shown in Fig. 6.1.
a) Name the product formed at the anode.
b) Name an ion found in the electrolyte.
c) State the name of the electrode where copper metal is formed.
d) Describe how copper metal is formed on this electrode
e) Explain why carbon is used as an electrode
7. Fig. 7.1 shows the apparatus needed for the electrolysis of dilute sulfuric acid
State the products formed at the:
Negative electrode……………………………………..
Positive electode ……………………………………….
8. Sodium chloride is an ionic compound.
(a) State and explain two properties of ionic compounds
(a) In an experiment, molten sodium chloride is electrolysed.
(i) Explain the meaning of electrolysis
(ii) (ii) Predict the products formed at each electrode during the electrolysis of molten
sodium chloride.
anode ................................................................................................................................
cathode ............................................................................................................................. [2]
(iii) Describe what happens, in terms of electrons, to the cations in sodium chloride during
electrolysis