Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit

Principles of Chemistry

991 practice questions

Start practising (991 questions)

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Practice questions

841–850 of 991

Question 841
4 marks · Normal
The diagram shows an apparatus used in the electrolysis of molten lead(II) iodide. The electrodes and power supply are labelled.
(a)
Explain what is meant by 'discharging an ion' during electrolysis.
[2 marks]
(b)
State what happens to the lead(II) ions at the cathode, referring to electron transfer.
[1 mark]
(c)
Write the ionic half-equation for the reaction at the anode.
[1 mark]
Answer and see the solution →
Question 842
3 marks · Normal
The electrolysis of molten potassium chloride (KCl) produces potassium metal and chlorine gas.
(a)
Write the half-equation for the reaction at the cathode.
[1 mark]
(b)
State whether the reaction at the cathode is oxidation or reduction.
[1 mark]
(c)
Explain your answer to part (b) in terms of electron transfer.
[1 mark]
Answer and see the solution →
Question 843
3 marks · Normal
A student wants to remember whether oxidation or reduction involves losing or gaining electrons.
(a)
State the mnemonic used to remember this.
[1 mark]
(b)
What does each letter in the mnemonic stand for?
[1 mark]
(c)
Explain, using the mnemonic, what happens to an ion that gains electrons.
[1 mark]
Answer and see the solution →
Question 844
4 marks · Normal
Table 1: Electrode Reactions
Ion Half-equation
Cl^- 2Cl^- \rightarrow Cl_2 + 2e^-
Ag^+ Ag^+ + e^- \rightarrow Ag
Fe^{3+} Fe^{3+} + 3e^- \rightarrow Fe
O^{2-} 2O^{2-} \rightarrow O_2 + 4e^-
Study Table 1. For each reaction below, state whether the ion is oxidised or reduced and explain why using electron transfer.
(a)
Cl^- \rightarrow Cl_2 + 2e^-
[1 mark]
(b)
Ag^+ + e^- \rightarrow Ag
[1 mark]
(c)
Fe^{3+} + 3e^- \rightarrow Fe
[1 mark]
(d)
O^{2-} \rightarrow O_2 + 4e^-
[1 mark]
Answer and see the solution →
Question 845
1 mark · Normal
In the electrolysis of molten zinc bromide, what does it mean to 'discharge' a zinc ion (Zn^{2+}) at the cathode?
1. A.Zinc ions lose electrons to form zinc atoms.
2. B.Zinc ions gain electrons to form zinc atoms.
3. C.Zinc atoms lose electrons to form zinc ions.
4. D.Zinc ions are removed from the solution by evaporation.
Answer and check →
Question 846
2 marks · Normal
For the electrolysis of molten calcium bromide (CaBr_2):
(a)
Which electrode (anode or cathode) is the site of oxidation?
[1 mark]
(b)
Which electrode reaction involves reduction?
[1 mark]
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Question 847
4 marks · Normal
You are asked to explain how the OILRIG mnemonic helps when deciding whether a reaction is oxidation or reduction.
(a)
Write what each letter in OILRIG stands for.
[2 marks]
(b)
Use the mnemonic to decide whether the following process is oxidation or reduction: Fe^{2+} gains 2 electrons to form Fe.
[1 mark]
(c)
State how the mnemonic helps you to answer part (b).
[1 mark]
Answer and see the solution →
Question 848
2 marks · Hard
Define oxidation and reduction in terms of electron transfer. Give your answers using complete sentences.
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Question 849
5 marks · Hard
The apparatus below is used to electrolyse molten tin(II) chloride (SnCl₂). Tin(II) ions (Sn²⁺) and chloride ions (Cl⁻) move towards the electrodes and react.
Electrolysis setup for molten tin(II) chloride
(a) State what is meant by 'discharging' a tin(II) ion during the electrolysis of molten tin(II) chloride.
(a)
State what is meant by 'discharging' a tin(II) ion during the electrolysis of molten tin(II) chloride.
[2 marks]
(b)
Explain, in terms of electron transfer, what happens to a tin(II) ion at the cathode in this process.
[2 marks]
(c)
Write a half-equation for the reaction involving tin(II) ions at the cathode.
[1 mark]
Answer and see the solution →
Question 850
2 marks · Hard
The electrolysis of molten iron(III) chloride (FeCl₃) involves reactions at both electrodes.
State which electrode reaction involves oxidation, and which involves reduction. Explain your answer with reference to loss or gain of electrons.
Answer and see the solution →

Ion	Half-equation
Cl^-	2Cl^- \rightarrow Cl_2 + 2e^-
Ag^+	Ag^+ + e^- \rightarrow Ag
Fe^{3+}	Fe^{3+} + 3e^- \rightarrow Fe
O^{2-}	2O^{2-} \rightarrow O_2 + 4e^-