Exam code: 5070
A student was investigating the electrolysis of zinc chloride.
What is the correct reason for electrolysis not working?
Solid zinc chloride has been used
The electrodes don't conduct electricity
The power supply is not connected properly
The crucible is too small to allow ions to flow
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Solid lead(II) bromide is heated until it is molten. The molten lead(II) bromide then undergoes electrolysis.
Which substances are formed at each electrode?
| anode | cathode |
A | bromine | lead |
B | lead | bromine |
C | bromine | hydrogen |
D | hydrogen | lead |
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The electrolysis of concentrated hydrochloric acid is shown.
Which statement describes what happens to the electrons during the electrolysis?
They are added to chloride ions.
They are added to hydrogen ions.
They move through the circuit from negative to positive.
They move through the solution from negative to positive.
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Concentrated aqueous sodium chloride can be electrolysed.
Which statement is correct?
Hydrogen gas is formed at the anode, and chlorine gas is formed at the cathode.
Hydrogen gas is formed at the cathode, and chlorine gas is formed at the anode.
Sodium metal is formed at the anode, and chlorine gas is formed at the cathode.
Sodium metal is formed at the cathode, and chlorine gas is formed at the anode.
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The diagram shows the electrolysis of concentrated hydrochloric acid and concentrated aqueous sodium chloride using carbon electrodes.
At which electrode(s) is hydrogen produced?
Electrode 1 only
Electrodes 1 and 3
Electrode 2 only
Electrodes 2 and 4
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Which metal could not be used for electroplating by using an aqueous solution?
Chromium
Copper
Silver
Sodium
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During electroplating what are the correct anode (positive electrode) and cathode (negative electrode) products when aqueous copper(II) sulfate is electrolysed using copper electrodes?
| Anode product | Cathode product |
A | copper(II) ions | copper metal |
B | copper(II) ions | hydrogen gas |
C | oxygen gas | copper metal |
D | oxygen gas | hydrogen gas |
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A student sets up the following equipment to investigate electroplating.
What would they see occur during the electroplating process?
The anode would be covered with an orange-pink coating
The cathode would be covered with a silver coating
The cathode would be covered with an orange-pink coating
The anode would be covered with a silver coating
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Which statement about electrolysis is correct?
Electrons move through the electrolyte from the cathode to the anode.
Electrons move towards the cathode in the external circuit.
Negative ions move towards the anode in the external circuit.
Positive ions move through the electrolyte towards the anode during electrolysis.
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Dilute sulfuric acid is electrolysed using inert electrodes.
What are the products of this electrolysis?
| cathode | anode |
A | oxygen | sulfur |
B | hydrogen | sulfur dioxide |
C | oxygen | hydrogen |
D | hydrogen | oxygen |
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Electricity is passed through concentrated aqueous sodium chloride. Inert electrodes are used.
Which products are formed at the electrodes?
| cathode | anode |
A | hydrogen | chlorine |
B | hydrogen | oxygen |
C | sodium | chlorine |
D | sodium | oxygen |
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The diagram shows the electrolysis of aqueous copper(II) sulfate.
Which statement is correct?
Copper metal is deposited at the positive electrode.
In the external circuit the electrons move from negative to positive.
In the solution the electrons move from positive to negative.
Oxygen gas is produced at the positive electrode.
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Concentrated aqueous potassium bromide solution is electrolysed using inert electrodes. The ions present in the solution are K+, Br–, H+ and OH–.
To which electrodes are the ions attracted during this electrolysis?
| attracted to anode | attracted to cathode |
A | Br– and K+ | H+ and OH– |
B | Br– and OH– | H+ and K+ |
C | H+ and K+ | Br– and OH– |
D | H+ and OH– | Br– and K+ |
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Which is the correct equation for the formation of chlorine gas at the anode during the electrolysis of concentrated sodium chloride solution?
Cl + e- → Cl-
2Cl- + 2e- → Cl2
2Cl- → Cl2 + 2e-
Cl- → Cl + e-
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The diagram shows a failed attempt to copper-plate a pan.
Which can be done to plate the pan with copper?
Cool the copper sulfate solution in an ice bath.
Heat the copper sulfate solution to boiling point.
Increase the voltage from 3 V to 6 V.
Make the pan the cathode and the copper the anode.
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The diagram shows a simple cell.
Which statement about the process occurring when the cell is in operation is correct?
Cu2+ ions are formed in solution.
Electrons travel through the solution.
The reaction Zn → Zn2+ + 2e– occurs.
The zinc electrode increases in mass
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A students wants to electroplate an iron spoon with silver using an aqueous silver salt as the electrolyte.
Which set of conditions is used?
| Iron spoon | Other electrode |
A | cathode | silver |
B | anode | silver |
C | cathode | carbon |
D | anode | carbon |
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An aqueous mixture of copper(II) nitrate and silver nitrate is electrolysed with pure copper electrodes.
Which half-equation correctly describes the change occurring at the anode?
Cu → Cu2+ + 2e–
Cu2+ + 2e– → Cu
Ag → Ag+ + e–
Ag+ + e– → Ag
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The diagram shows the electrolysis of concentrated and dilute aqueous sodium chloride using inert electrodes. Gases are produced and collected in each of the test-tubes W, X, Y and Z.
Which statements are correct?
Approximately equal volumes of gas are produced and collected in test-tubes W and X.
Approximately equal volumes of gas are produced and collected in test-tubes Y and Z.
Three different gases are produced in the experiment.
1, 2 and 3
1 and 2 only
2 and 3 only
1 and 3 only
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Which positive ions are present in aqueous copper(II) sulfate?
copper(II) ions only
copper(II) ions and hydrogen ions
sulfate ions only
sulfate ions and hydroxide ions
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Which reactions take place during the extraction of aluminium from aluminium oxide using carbon electrodes?
2O2– → O2 + 4e–
C + O2 → CO2
Al2+ + 2e– → Al
1 only
1 and 2 only
2 and 3 only
1, 2 and 3
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Carbon electrodes are used to electrolyse aqueous copper(II) sulfate.
Which observations are made?
| at the anode | electrolyte | at the cathode |
A | colourless gas forms | blue colour fades | pink solid forms |
B | colourless gas forms | blue colour fades | colourless gas forms |
C | electrode increases in mass | blue colour fades | pink solid forms |
D | electrode increases in mass | no change | pink solid forms |
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Electrolysis is used to plate a metal coin with silver.
The coin is used as an electrode in a suitable electrolyte.
Which row is correct?
| coin | electrolyte |
A | anode | AgCl(aq) |
B | anode | AgNO3(aq) |
C | cathode | AgCl(aq) |
D | cathode | AgNO3(aq) |
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The diagram shows the electrolysis of concentrated aqueous sodium chloride.
What is the colour of the litmus at each electrode after five minutes?
| colour at anode | colour at cathode |
A | blue | red |
B | red | blue |
C | red | colourless |
D | colourless | blue |
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Four substances are electrolysed. The substances are concentrated aqueous sodium chloride, concentrated hydrochloric acid, molten lead(II) bromide and molten sodium oxide.
Which statement about these electrolysis reactions is correct?
A colourless gas is formed at the anode when molten sodium oxide is electrolysed.
A green gas is formed at the cathode when concentrated hydrochloric acid is electrolysed.
A metal is formed at the anode when molten lead(II) bromide is electrolysed.
A metal is formed at the cathode when concentrated aqueous sodium chloride is electrolysed.
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Four solutions are separately electrolysed.
experiment | solution | electrodes |
1 | dilute aqueous sodium chloride | carbon |
2 | aqueous copper(II) sulfate | copper |
3 | concentrated hydrochloric acid | carbon |
4 | dilute sulfuric acid | carbon |
In which two experiments is a colourless gas evolved at the anode?
1 & 2
1 & 4
2 & 3
3 & 4
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During electrolysis of brine, a gas is produced at the cathode. What is the half-equation for the reaction on the cathode?
2Cl- → Cl2 + 2e-
2Cl- + 2e- → Cl2
2H+ + 2e- → H2
2H+ → H2 + 2e-
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The amount of gases P and Q are formed when substance X is electrolysed.
What is substance X?
molten zinc bromide
dilute sulfuric acid
concentrated aqueous sodium bromide
concentrated hydrochloric acid
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Concentrated aqueous sodium chloride, dilute sulfuric acid and molten lead bromide were electrolysed separately in experiments 1, 2 and 3.
Which statement about the electrode products is correct?
Metals were formed at the anode in experiments 1 and 3 only
Metals were formed at the cathode in experiments 1 and 3 only
Gases are given off at the cathode in experiments 1 and 2 only
Gases are given off at the anode in experiments 2 and 3 only
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A student wants to identify the gas produced at the negative electrode during the electrolysis of aqueous sodium chloride.
What is the correct test for the gas produced?
A glowing splint will relight
A burning splint gives a squeaky pop sound
Damp litmus paper bleaches
Damp red litmus paper turns blue
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A student wishes to electroplate an object with copper.
Which row is correct?
| object is made at the | a suitable electrolyte is |
A | anode | CuO(s) |
B | anode | CuSO4(aq) |
C | cathode | CuO(s) |
D | cathode | CuSO4(aq) |
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Winston Churchill, a British Prime Minister, had his false teeth electroplated with gold.
The teeth were coated with a thin layer of carbon and were then placed in the apparatus shown.
| terminal X is | the carbon powder could be |
A | negative | diamond |
B | negative | graphite |
C | positive | diamond |
D | positive | graphite |
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The diagram shows an electrolysis experiment using X and Y as electrodes.
Copper is used to coat the other metal.
Which metal becomes coated and which solution is used?
| aqueous solution | metal |
A | CoCl3 | Y |
B | CuCl2 | Y |
C | CuCl2 | X |
D | CoCl3 | X |
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The following apparatus for plating a spoon with silver is shown.
Which statements are correct?
1 The metal electrode would be connected to the negative terminal of the power supply
2 The spoon would be connected to the negative terminal of the power supply
3 At the cathode, silver ions lose electrons to form silver atoms
4 At the anode, silver atoms lose electrons to form silver ions
2 only
1 and 4 only
2 and 4 only
1, 2 and 3
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