Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Electrolysis
198 practice questions
Topics covered
- Why things conduct electricity17 practice questions
- Passing electricity through compounds: electrolysis20 practice questions
- The electrolysis of molten compounds19 practice questions
- Electrolysis and redox19 practice questions
- The electrolysis of other molten substances19 practice questions
- The electrolysis of aqueous solutions18 practice questions
- The electrolysis of sodium chloride solution19 practice questions
- The electrolysis of copper(ii) sulfate solution using inert electrodes18 practice questions
- The electrolysis of some other solutions using inert electrodes19 practice questions
- What would happen with non-electrolytes?19 practice questions
Practice questions
181–190 of 198
Question 181
1 mark · Normal
Answer and check →The student sets up an apparatus to test substance X for electrical conductivity. The bulb stays off, and even after substance X is dissolved in water, there is still no current. What does this suggest about substance X?
- A.It is an ionic compound that conducts electricity when solid.
- B.It is a covalent compound that forms ions in water.
- C.It is a non-electrolyte and does not produce ions in solution.
- D.It is an acid and must form ions in solution.
Question 182
2 marks · Normal
Answer and see the solution →Explain why potassium iodide (KI) will conduct electricity when molten but not as a solid.
Question 183
4 marks · Normal
Answer and see the solution →You are given a white solid (substance Y) that is soluble in water. You need to determine whether it is an ionic compound, a covalent compound, or a non-electrolyte.
(a)[2 marks]Describe an experiment you could do to determine the type of substance.
(b)[2 marks]State what you would observe if substance Y is an ionic compound and explain your answer.
Question 184
3 marks · Normal
Answer and see the solution →A student wants to find out whether substance X is an ionic compound, a covalent compound (non-electrolyte), or an acid using an experiment. She sets up the following experiment in which two carbon electrodes are placed in a solution of substance X, connected to a power supply and a bulb, as shown in the diagram:
Apparatus for testing conductivity. In three separate experiments she uses:
Test Substance in solution Observation A X dissolved in water Bulb does not light up B Molten X Bulb lights up C Aqueous acid Bulb lights up Using the data above, calculate whether substance X is ionic, covalent (non-electrolyte), or an acid. Explain your reasoning.
Question 185
2 marks · Hard
Answer and see the solution →A student tries to electrolyse solid iodine and observes no current flows through the circuit. The student then dissolves the iodine in water and tries again, but the bulb still does not light. State and explain what these results show about the electrical properties and bonding type of iodine.
Question 186
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 187
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 188
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 189
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 190
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.