Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Principles of Chemistry
991 practice questions
Topics covered
- States of Matter102 practice questions
- Elements, Compounds and Mixtures69 practice questions
- Atomic Structure108 practice questions
- The Periodic Table103 practice questions
- Chemical Formulae, Equations and Calculations Part 119 practice questions
- Chemical Formulae, Equations and Calculations Part 2144 practice questions
- Ionic Bonding143 practice questions
- Covalent Bonding68 practice questions
- Metallic Bonding19 practice questions
- Electrolysis198 practice questions
Practice questions
961–970 of 991
Question 961
5 marks · Hard
Answer and see the solution →A student investigates the electrical conductivity of three white solids: compound A, compound B and compound C. The student tests each substance (i) as a solid, (ii) after dissolving it in water, and (iii) after melting it. The observations are recorded below:
Conductivity results for three compounds Substance Solid Aqueous solution Molten Compound A Does not conduct Does not conduct Does not conduct Compound B Does not conduct Conducts Conducts Compound C Does not conduct Does not conduct Conducts (a)[4 marks]For each compound (A, B and C), state whether it is ionic, covalent (non-electrolyte), or another type. Give a reason for each answer.
(b)[1 mark]Suggest a familiar example of a substance that would behave in the same way as compound A.
Question 962
2 marks · Hard
Answer and see the solution →A student is investigating whether a white crystalline solid is an ionic compound or a covalent compound. The student finds that the solid does not conduct electricity, and that dissolving the solid in water still does not allow the solution to conduct electricity. State what type of compound the solid is and explain your reasoning.
Question 963
5 marks · Easy
Answer and see the solution →The table shows some properties of substances at room temperature.
(a)Substance Properties Substance Type of Bonding Solid? (yes/no) Molten? (yes/no) In solution? (yes/no) Conducts electricity? (yes/no) Copper Metallic Yes No No Yes Sodium chloride (NaCl) Ionic Yes Yes Yes No Methane (CH4) Covalent Yes No No No (i)[1 mark]State one reason why copper conducts electricity as a solid.
(ii)[1 mark]Give one reason why solid sodium chloride does not conduct electricity.
(iii)[1 mark]Explain how sodium chloride can be made to conduct electricity.
(b)You pass electricity through molten sodium chloride using a simple cell and two inert (carbon) electrodes.
(i)[1 mark]In this experiment, what is the name given to the liquid sodium chloride?
(ii)[1 mark]State the name given to the positive electrode and the negative electrode.
Question 964
5 marks · Easy
Answer and see the solution →A student compares the electrolysis of molten lead(II) bromide with the electrolysis of aqueous sodium chloride solution.
(a)[2 marks]State the product formed at the cathode during the electrolysis of molten lead(II) bromide. Explain your answer briefly.
(b)[3 marks]Describe how to set up the apparatus to investigate the electrolysis of an aqueous sodium chloride solution. State one safety precaution.
Question 965
5 marks · Easy
Answer and see the solution →This question is about balancing half-equations for the electrolysis of ionic compounds.
(a)[2 marks]Write the balanced ionic half-equation (including state symbols) for the reaction at the anode during the electrolysis of molten zinc(II) chloride.
(b)[2 marks]State the product formed at the anode and the product formed at the cathode during the electrolysis of concentrated aqueous sodium chloride solution.
(c)[1 mark]Explain why less chlorine gas is collected at the anode than expected, even if the reaction has gone to completion.
Question 966
5 marks · Easy
Answer and see the solution →A student investigates the electrolysis of two different substances using graphite electrodes:
(a)[2 marks]Molten lead(II) bromide (PbBr₂) is electrolysed. Predict which element forms at the cathode and which at the anode. Explain how you know.
(b)The student now electrolyses concentrated aqueous magnesium chloride (MgCl₂(aq)). After testing the gases, they find the volume of chlorine gas collected at the anode is much less than the volume of hydrogen collected at the cathode.
(i)[1 mark]Explain why hydrogen, and not magnesium, is formed at the cathode.
(ii)[2 marks]Give a reason why less chlorine gas is collected at the anode than expected.
Question 967
6 marks · Normal
Answer and see the solution →Potassium iodide (KI) is an ionic compound. When heated until molten and electrolysed using inert electrodes, iodine gas is produced at one electrode and potassium metal at the other.
(a)[1 mark]State the ions present in molten potassium iodide.
(b)[1 mark]Write the half-equation for the reaction occurring at the cathode.
(c)[1 mark]Write the half-equation for the reaction occurring at the anode.
(d)[2 marks]State, in terms of electron transfer, which reaction involves reduction and which involves oxidation.
(e)[1 mark]Explain how you can use the mnemonic OILRIG to identify which reaction at the electrodes is oxidation and which is reduction.
Question 968
6 marks · Normal
Answer and see the solution →A student carries out the electrolysis of molten calcium chloride (CaCl2) in a laboratory using inert carbon electrodes.
(a)[2 marks]State what is meant by 'discharging an ion' during electrolysis.
(b)[1 mark]Identify the ions in molten calcium chloride and their movement during electrolysis.
(c)[1 mark]Write the half-equation for the discharge of chloride ions at the anode.
(d)[2 marks]Explain, using electron transfer, what happens to a calcium ion during electrolysis.
Question 969
6 marks · Normal
Answer and see the solution →A student sets up an electrolysis experiment using molten potassium iodide (KI). An external circuit with a bulb lights up when the current is switched on.
(a)[2 marks]State the ions present in molten potassium iodide. Identify which ions move towards the cathode and which move towards the anode during electrolysis.
(b)[1 mark]Write the ionic half-equation for the reaction occurring at the cathode.
(c)[1 mark]Write the ionic half-equation for the reaction occurring at the anode.
(d)[2 marks]For the electrode reaction at the cathode, state whether it is an oxidation or a reduction. Justify your answer using the concept of electron transfer.
Question 970
6 marks · Normal
Answer and see the solution →During the electrolysis of molten calcium chloride (CaCl2), calcium forms at one electrode and chlorine gas is released at the other.
(a)[2 marks]Write the balanced ionic half-equation for the reaction at the electrode where chlorine gas is produced.
(b)[2 marks]Explain what is meant by the term 'discharging an ion' using Ca^2+ or Cl^- as an example from this electrolysis process.
(c)[2 marks]Recall the meaning of the mnemonic OILRIG and use it to decide whether the reaction at the chlorine-producing electrode is an oxidation or a reduction.