4. Electrochemistry
A section of Chemistry, 0620
Listing 10 of 500 questions
Copper is element 29 in the Periodic Table. Brass contains copper. Name the other metal in brass. State the term given to a mixture of a metal with another element. Copper can be stretched into wires. Copper wires conduct electricity. Name the property of metals which means that they can be stretched into wires. Name the particles responsible for the conduction of electricity in solid copper. Copper is a transition element. Some physical and chemical properties of transition elements are shown. physical properties: ● high density ● high strength chemical properties: ● form coloured compounds ● have ions with variable oxidation numbers State one other physical property of transition elements. State one other chemical property of transition elements. Hydrated copper(sulfate is a coloured compound. It exists as hydrated crystals which contain water molecules. State the term given to water molecules present in hydrated crystals. State the colour of hydrated copper(sulfate crystals. Write the formula of hydrated copper(sulfate. Copper(oxide is formed when copper(nitrate, Cu(NO3)2, is heated. 2Cu(NO3)2→ 2CuO+ 4NO2+ O2State the class of oxide to which copper(oxide belongs. State the meaning of the Roman numeral (in the name copper(oxide. 0.0200moles of Cu(NO3)2 is heated. Calculate the mass of 0.0200moles of Cu(NO3)2.  mass = g Calculate the total volume of gas, in dm3 at r.t.p., produced when 0.0200 moles of Cu(NO3)2 is heated.  volume = dm3 Powdered aluminium reduces copper(oxide. Write the symbol equation for this reaction. 
0620_m23_qp_42
THEORY
2023
Paper 4, Variant 2
View
Copper(sulfate is heated strongly. The products are copper(oxide and sulfur trioxide. heat CuSO4 → CuO + SO3 What type of reaction is this? Tick one box. addition neutralisation oxidation thermal decomposition Sulfur trioxide is an acidic gas. What precautions must be taken when heating copper(sulfate in the laboratory? The diagram below shows the arrangement of sulfur trioxide molecules at 30 °C. SO3 molecules key What is the state of sulfur trioxide at 30 °C? Use the information in the diagram to explain your answer. Sulfur trioxide dissolves in water to form sulfuric acid. Complete the symbol equation for this reaction. SO3 + H2O → Sulfuric acid is strongly acidic. Which one of the following pH values is strongly acidic? Put a ring around the correct answer. pH 1 pH 6 pH 7 pH 9 pH 13 Copper(oxide is a solid. An aqueous solution of copper(sulfate can be made by heating excess copper(oxide with dilute sulfuric acid. Draw a labelled diagram of the apparatus you would use to separate the excess copper(oxide from the solution. Anhydrous copper(sulfate can be used to test for water. CuSO4+ 5H2OCuSO4.5H2OWhat is the meaning of the symbol ? Give the colour change when water is added to anhydrous copper(sulfate. from to
0620_s15_qp_23
THEORY
2015
Paper 2, Variant 3
View
A teacher passed hydrogen gas over hot copper(oxide. CuO+ H2→Cu+ H2OWhich substance is reduced in this reaction? Explain your answer. 1 11 The diagram shows the apparatus used. dry hydrogen gas copper(oxide water ice bath The hydrogen was passed over the hot copper(oxide until the reaction was complete. As the experiment proceeds, suggest what happens to the mass of copper(oxide. Suggest why electrical heating is used in this experiment and not a Bunsen burner. Describe the chemical test for the presence of water. test result [ 1 11
0620_s16_qp_31
THEORY
2016
Paper 3, Variant 1
View
This question is about copper and copper compounds. Describe how you could prepare a pure sample of crystals of hydrated copper(sulfate using dilute sulfuricacid and an excess of copper(oxide. Anhydrous copper(sulfate is used to test for water. CuSO4 + 5H2O CuSO4.5H2O anhydrous hydrated copper(sulfate copper(sulfate What is meant by the symbol ? How can hydrated copper(sulfate be changed into anhydrous copper(sulfate? Complete the table to calculate the relative formula mass of anhydrous copper(sulfate, CuSO4. Use your Periodic Table to help you. type of atom number of atoms relative atomic mass copper 1 × 64 = 64 sulfur oxygen  relative formula mass =  Complete the table to show the number of electrons, protons and neutrons in the sulfur atom and copper ion shown. number of electrons number of neutrons number of protons 34S 63Cu2+  Alloys of copper are used to make coins. What is meant by the term alloy? Suggest why an alloy of copper is used to make coins instead of using pure copper. 
0620_s19_qp_31
THEORY
2019
Paper 3, Variant 1
View
Copper(sulfate crystals, CuSO4.5H2O, are hydrated. Copper(sulfate crystals are made by reacting copper(carbonate with dilute sulfuricacid. The equation for the overall process is shown. CuCO3 + H2SO4 + 4H2O CuSO4.5H2O + CO2 step 1 Powdered solid copper(carbonate is added to 50.0 cm3 of 0.05 mol / dm3 sulfuricacid until the copper(carbonate is in excess. step 2 The excess of copper(carbonate is separated from the aqueous copper(sulfate. step 3 The aqueous copper(sulfate is heated until the solution is saturated. step 4 The solution is allowed to cool and crystallise. step 5 The crystals are removed and dried. Calculate the maximum mass of the copper(sulfate crystals, CuSO4.5H2O, that can form using the following steps. ● ● Calculate the number of moles of H2SO4 in 50.0 cm3 of 0.05 mol / dm3 H2SO4.  mol ● ● Determine the number of moles of CuSO4.5H2O that can form.  mol ● ● The Mr of CuSO4.5H2O is 250. Calculate the maximum mass of CuSO4.5H2O that can form.  g  Steps 1–5 were done correctly but the mass of crystals obtained was less than the maximum mass. Explain why. State two observations that would indicate that the copper(carbonate is in excess in step1.  When the reaction in step1 is done using lumps of copper(carbonate instead of powder, the rate of reaction decreases. All other conditions are kept the same. Give a reason for this. Explain your answer in terms of particles. Name a different substance, other than copper(carbonate, that could be added to dilute sulfuricacid to produce copper(sulfate in step1. Name the process used to separate the aqueous copper(sulfate from the excess of copper(carbonate in step2. The solution of aqueous copper(sulfate was heated until it was saturated in step3. Suggest what is meant by the term saturated solution. What evidence would show that the solution was saturated in step3? Why should the aqueous copper(sulfate not be heated to dryness in step3? 
0620_s19_qp_42
THEORY
2019
Paper 4, Variant 2
View
Questions Discovered
500