Essential Chemistry for IGCSE - Electricity And Chemistry (Section 8)
1
Which of the following are common industrial applications of electrolysis? (Select all that apply)
2
What type of current is used in electroplating?
3
In the electrolysis of molten lead(II) bromide, what is the product formed at the cathode?
4
During electrolysis, what role does the power source play?
Answer(B)
It provides the energy needed for the non-spontaneous reaction.
5
In the electrolysis of copper sulfate solution using copper electrodes, which of the following statements is correct?
Answer(A)
The anode dissolves, and copper is deposited at the cathode.
6
What is the reason that the carbon anodes in the electrolysis cell are continually replaced?
Answer(C)
To replace the carbon consumed during the reaction with oxygen.
7
What process is used to purify the bauxite ore before extracting aluminum?
Answer(C)
Reaction with sodium hydroxide followed by filtration.
8
What would happen if, during the electrolysis of copper sulfate solution, the copper anode was replaced with a carbon (inert) anode?
Answer(B)
Oxygen would be produced at the anode.
9
What is a major use of electroplating?
Answer(C)
To protect metals from corrosion
10
The electrolysis of molten aluminum oxide uses carbon electrodes. What happens to the carbon anodes during electrolysis?
Answer(C)
They react with oxygen to form carbon dioxide.
11
During the extraction of aluminum, why is it important to keep the electrolyte at a high temperature for long periods of time?
Answer(B)
To ensure the aluminum oxide is molten.
12
Why is the electrolysis of aluminum oxide carried out at a temperature of around 900°C instead of 2040°C?
Answer(C)
To reduce energy consumption.
13
What is the function of a diaphragm in the electrolysis of brine to produce chlorine?
Answer(B)
To separate the chlorine gas from the other products
14
What is the name of the ore from which aluminum is extracted?
15
What occurs at the cathode during the electrolysis of molten sodium chloride (NaCl)?
16
What is the standard electrolyte used in the electroplating of copper?
17
During the electrolysis of acidified water, what will happen to the hydrogen ions?
Answer(B)
They will be reduced at the cathode.
18
In the electrolysis of a concentrated aqueous solution of sodium chloride, which product is formed at the anode?
19
What happens to the impurities during the refining of copper?
Answer(C)
They form a sludge (anode mud) at the bottom of the cell.
20
Why is high voltage used in transmission lines?
Answer(A)
To reduce power loss during transmission.
21
What is the role of the metal object being electroplated?
22
What happens to the concentration of the electrolyte during the electrolysis of copper sulfate with copper electrodes? (Select all that apply)
23
Which statements are true concerning the electrolysis of concentrated aqueous sodium chloride? (Select all that apply)
24
What is the purpose of electroplating in terms of protecting metals?
Answer(B)
To protect the metal from corrosion.
25
What happens to the mass of the cathode during the electroplating of copper?
26
What is the primary function of the electrolyte in the electrolytic cell used to extract aluminum?
Answer(B)
To conduct electricity by allowing ion movement.
27
Which of the following is/are a property of conductors?
28
Which of the following is a key advantage of using thick wires in high-voltage power lines?
Answer(A)
Reduced resistance, less heat loss, and ability to carry more current.
29
In the electroplating process, which of the following is NOT necessary?
Answer(D)
A direct current source and an AC source
30
During the electrolysis of molten aluminum oxide, what happens to the oxide ions?
Answer(C)
They lose electrons at the anode.
31
Which of the following are advantages of using thick wires over thin wires in high-voltage power lines?
32
Why is aluminium used in high-voltage power lines instead of copper?
Answer(B)
Because it is lighter and easier to transport.
33
Which of the following is NOT a common use of electroplating?
34
Why are the carbon anodes replaced during the electrolysis of aluminum oxide?
Answer(C)
Because they react with the oxygen produced, forming carbon dioxide.
35
In the electrolysis of molten lead(II) bromide (PbBr₂), what is the oxidation half-reaction?
36
In the electrolysis of copper sulfate solution with inert electrodes, what is formed at the cathode?
37
In an electric circuit, a thick wire is used in the place of a thin wire. Which of the following correctly describes the effect on the circuit?
38
Which of the following is/are an application(s) of electrochemistry? (Select all that apply)
39
What do you understand by the term insulator?
Answer(A)
A substance that resists the flow of an electric current
40
What is the purpose of the steel core in steel-cored aluminum cables used in high-voltage power lines?
Answer(B)
To increase the cable's tensile strength.
41
What are the main products of electrolysis of concentrated NaCl solution (brine)? (Select all that apply)
42
In the electrolysis of dilute sulfuric acid, which of the following products is formed at the cathode?
43
Which of the following is/are reasons why insulators are used?
44
Which of the following statements is true about the electrolysis of acidified water?
Answer(C)
The volume of hydrogen produced is twice the volume of oxygen produced.
45
What is the role of the sodium hydroxide in the purification of bauxite ore?
Answer(B)
To dissolve the aluminum oxide.
46
During electroplating of an iron spoon with silver, what should the electrolyte contain?
47
What are the two products formed during the electrolysis of aqueous sodium chloride (brine)?
48
What is the standard unit used to measure the electrical current during electrolysis?
49
Which of the following is a key application of electroplating?
Answer(B)
Protecting metals from corrosion
50
Which of the following metals is commonly used as the cathode in electroplating?
