4.1. Electrolysis
A subsection of Chemistry, 0620, through 4. Electrochemistry
Listing 10 of 449 questions
The diagram shows part of the structures of sodiumchloride and pentane at room temperature and pressure. represents pentane, CH3CH2CH2CH2CH3 Na+ Cl – Na+ Cl – Na+ Cl – Na+ Cl – Cl – Na+ Na+ Cl – Describe the differences in the physical properties of these substances in terms of: ● volatility sodium chloride pentane ● solubility in water sodium chloride pentane ● electrical conductivity when molten . sodium chloride pentane  Concentrated aqueous sodiumchloride is electrolysed using carbon electrodes. Name the gas produced at the positive electrode. Pentane is a fuel. Under some conditions pentane forms carbonmonoxide. State the condition under which pentane forms carbonmonoxide. State one adverse effect of carbonmonoxide on health. 
0620_w21_qp_33
THEORY
2021
Paper 3, Variant 3
View
Lead is a metallic element in GroupIV. One of the ores of lead is galena, which is an impure form of lead(sulfide, PbS. Lead also occurs in the ore cerussite, which contains lead(carbonate, PbCO3. Calculate the relative formula mass, Mr, of PbCO3.  Mr of PbCO3 = The Mr of PbS is 239. Calculate the percentage of lead by mass in PbS.  percentage of lead by mass in PbS = The percentage of lead by mass in PbCO3 is 77.5%. Use this information and your answer to to suggest whether it would be better to extract lead from PbCO3 or PbS. Give a reason for your answer. When lead(carbonate is heated it decomposes into lead(oxide, PbO, and carbondioxide. Write a chemical equation for this reaction. Lead(carbonate reacts with dilute nitricacid. One of the products is aqueous lead(nitrate, Pb(NO3)2. Write a chemical equation for this reaction. Lead(oxide and carbondioxide are oxides of GroupIV elements. Complete the diagram to show the electron arrangement in one molecule of CO2. Show only the outer electrons. O O C  The melting points of lead(oxide and carbondioxide are shown. melting point / °C lead(oxide carbon dioxide –56 Use your knowledge of structure and bonding to explain why lead(oxide has a much higher melting point than carbondioxide. Your answer should refer to: ● the types of particles involved ● the relative strength of the forces of attraction between the particles. Part of the reactivity series is shown. magnesium most reactive lead copper least reactive Aqueous lead(nitrate contains Pb2+ ions. Two experiments are carried out. In Experiment1, magnesium is added to aqueous lead(nitrate. In Experiment2, copper is added to aqueous lead(nitrate. Write an ionic equation for any reaction that occurs in each experiment. If no reaction occurs write ‘no reaction’. Experiment 1 Experiment 2  When lead(nitrate is heated it decomposes to produce the same gaseous products as when copper(nitrate is heated. One of the gaseous products is oxygen. Describe a test for oxygen. test observations  Name the other gaseous product. 
0620_w21_qp_43
THEORY
2021
Paper 4, Variant 3
View
Zincchloride is an ionic compound. Ionic compounds are good electrical conductors when molten or in aqueous solution. Describe one other physical property of ionic compounds. Complete Fig.8.1 to show: ● the electronic configuration of a chloride ion ● the charge on the ion. Cl  Deduce the number of protons and neutrons in the zinc ion shown. 67Zn2+ number of protons number of neutrons  Complete this sentence about positive ions. Positive ions are known as . Molten zincchloride is electrolysed using graphite electrodes. State the names of the products at each electrode and give the observations at the positive electrode. product at the negative electrode product at the positive electrode observations at the positive electrode  Graphite electrodes conduct electricity. State one other property that the electrode should have. Choose the correct statement about the structure and bonding in graphite. Tick (✓) one box. simple ionic simple covalent giant ionic giant covalent  State one use of graphite other than as an electrode. 
0620_w23_qp_32
THEORY
2023
Paper 3, Variant 2
View
This question is about lead(chloride, PbCl 2. A student prepares a sample of insoluble lead(chloride, PbCl 2, by mixing aqueous solutions of two salts in a beaker. Identify two soluble salts suitable for making lead(chloride when mixed together. Write the ionic equation for the formation of lead(chloride by mixing aqueous solutions. Include state symbols. List the steps the student should take in preparing a pure sample of lead(chloride from the mixture in the beaker. The student carries out an electrolysis experiment on molten lead(chloride using the apparatus shown in Fig.4.1. Chlorine gas forms at the anode and escapes from the apparatus. power supply molten lead(chloride Explain why lead(chloride needs to be molten before it will conduct electricity. Write the ionic half-equation for the reaction occurring at the anode. State the test for chlorine gas. test observations  Describe what is observed at the cathode. 
0620_w23_qp_42
THEORY
2023
Paper 4, Variant 2
View
A student investigates the reaction of small pieces of zinc with excess dilute sulfuric acid of three different concentrations. The time taken for each reaction to finish is recorded. The three concentrations of the acid are: ● 0.2 mol / dm3 ● 0.4 mol / dm3 ● 0.8 mol / dm3. All other conditions stay the same. Table 8.1 shows the time taken for each reaction to finish. Table 8.1 concentration of dilute sulfuric acid in mol / dm3 time taken for the reaction to finish in s Complete Table 8.1 by writing the concentrations in the first column. Describe the effect on the time taken for the reaction to finish when the reaction is carried out in the presence of a catalyst. All other conditions stay the same. Describe the effect on the time taken for the reaction to finish when larger pieces of zinc are used instead of small pieces of zinc. All other conditions stay the same. Dilute sulfuric acid is electrolysed using inert electrodes. Name the products at the positive and negative electrodes. product at the positive electrode product at the negative electrode Choose from the list the metal used as an inert electrode. Draw a circle around your chosen answer. calcium magnesium platinum sodium Zinc is a solid at room temperature. Describe the arrangement and separation of the particles in solid zinc. arrangement separation
0620_w24_qp_31
THEORY
2024
Paper 3, Variant 1
View
A student investigates the reaction of small pieces of calcium carbonate with excess dilute hydrochloric acid of three different concentrations. The time taken for each reaction to finish is recorded. The three concentrations of acid are: ● 0.5 mol / dm3 ● 1.0 mol / dm3 ● 2.0 mol / dm3. All other conditions stay the same. Table 8.1 shows the time taken for each reaction to finish. Table 8.1 concentration of dilute hydrochloric acid in mol / dm3 time taken for the reaction to finish in s Complete Table 8.1 by writing the concentrations in the first column. Describe the effect on the time taken for the reaction to finish when the reaction is carried out at a lower temperature. All other conditions stay the same. Describe the effect on the time taken for the reaction to finish when powdered calcium carbonate is used instead of small pieces of calcium carbonate. All other conditions stay the same. Molten calcium chloride is electrolysed using inert electrodes. Name the products at the positive and negative electrodes. product at the positive electrode product at the negative electrode Choose from the list the substance that is used as an inert electrode. Draw a circle around your chosen answer. graphite iodine magnesium phosphorus Carbon dioxide is a gas at room temperature. Describe the motion and separation of the particles in carbon dioxide gas. motion separation
0620_w24_qp_32
THEORY
2024
Paper 3, Variant 2
View
A student investigates the reaction of small pieces of magnesium oxide with excess dilute hydrochloric acid of three different concentrations. The time taken for each reaction to finish is recorded. The three concentrations of the acid are: ● 0.4 mol / dm3 ● 0.8 mol / dm3 ● 1.6 mol / dm3. All other conditions stay the same. Table 8.1 shows the time taken for each reaction to finish. Table 8.1 concentration of dilute hydrochloric acid in mol / dm3 time taken for the reaction to finish in s Complete Table 8.1 by writing the concentrations in the first column. Describe the effect on the time taken for the reaction to finish when the reaction is carried out at a lower temperature. All other conditions stay the same. Describe the effect on the time taken for the reaction to finish when large pieces of magnesium oxide are used instead of small pieces of magnesium oxide. All other conditions stay the same. Molten magnesium chloride is electrolysed using inert electrodes. Name the products at the positive and negative electrodes. product at the positive electrode product at the negative electrode Describe the arrangement, motion and separation of the particles in liquid magnesium chloride. arrangement motion separation
0620_w24_qp_33
THEORY
2024
Paper 3, Variant 3
View
Questions Discovered
449