1 1 Limestone rock is mainly calcium carbonate, CaCO3. The ‘limestone cycle’ is shown. Each step is numbered. limestone step 1 heat calcium carbonate lime Calcium oxide ................................... Cao ................................... CaCO3(s) step 2 add limited water step 4 add CO2 limewater slaked lime calcium hydroxide calcium hydroxide Ca(OH)2(aq) step 3 add an excess of water Ca(OH)2(s) (a) Complete the box to give the chemical name and formula of lime. [2] (b) Which step involves a physical change? step 3 ........................................................................................................................................... [1] (c) What type of reaction is step 1? ........................................................................................................................................... [1] (d) Suggest how step 2 could be reversed. ........................................................................................................................................... [1] (e) Write a chemical equation for step 4. ........................................................................................................................................... (f) [1] Explain why step 4 is a neutralisation reaction. Refer to the substances reacting in your answer. Co2-acidic and Ca(OH)2 basic ........................................................................................................................................... [2] [Total: 8] 2 Element X can undergo the following physical changes. 2 gaseous X boiling or evaporation 2 4 liquid X 3 1 solid X (a) Give the scientific name for each of the numbered physical changes. 1 ........................................................................................................................................ 2 ........................................................................................................................................ 3 ........................................................................................................................................ 4 ........................................................................................................................................ [4] (b) Explain why the changes shown are physical changes. ........................................................................................................................................... ........................................................................................................................................... [1] (c) One difference between boiling and evaporation is the rate at which the processes occur. State one other difference between boiling and evaporation. ........................................................................................................................................... ........................................................................................................................................... [1] [Total: 6] 3 3 Substance Y undergoes physical and chemical changes. Which two of the following are physical changes? Explain your answer. A Substance Y dissolves easily in water. B An aqueous solution of substance Y gives a white precipitate with acidified aqueous silver nitrate. C Substance Y melts at 801 °C. D Substance Y reacts with concentrated sulfuric acid. .................................................................................................................................................. .................................................................................................................................................. .................................................................................................................................................. [3] [Total: 3] 4 4 Substance P undergoes physical and chemical changes. Which two of the following are physical changes? Explain your answer. A Substance P reacts with concentrated sulfuric acid. B Iodine forms when chlorine is added to an aqueous solution of substance P. C Substance P boils at 1330°C. D Substance P dissolves easily in water. .................................................................................................................................................. .................................................................................................................................................. .................................................................................................................................................. [3] [Total: 3] 5 Aqueous chlorine reacts with aqueous sodium iodide. Cl2 + 2NaI → I2 + 2NaCl (a) How does this reaction show that chlorine is more reactive than iodine? ........................................................................................................................................... [1] (b) What colour is iodine in aqueous solution? ........................................................................................................................................... [1] [Total: 2] 6 The equation shows the effect of heat on anhydrous zinc sulfate. ZnSO4 → ZnO + SO3 5 (a) What type of chemical reaction is this? Tick one box. addition decomposition displacement oxidation [1] (b) When 12.60 g of anhydrous zinc sulfate is heated, the mass of zinc oxide formed is 6.34 g. Calculate the mass of zinc oxide formed when 63.0 g of anhydrous zinc sulfate is heated. 31.7 mass of zinc oxide = ........................... g [1] [Total: 2] 7 Balance the chemical equation for the complete combustion of ethanol. C2H5OH + 3O2 → ....... CO2 + ......... H2O [2] [Total: 2] 8 Solutions of ionic compounds can be broken down by electrolysis. Concentrated aqueous copper(II) chloride was electrolysed using the apparatus shown. 6 power supply – + cathode made of platinum anode made of platinum concentrated aqueous copper(II) chloride The ionic half-equations for the reactions at the electrodes are shown. 2+ negative electrode: Cu (aq) + 2e – – → Cu(s) positive electrode: 2Cl (aq) → Cl2(g) + 2e – (a) Platinum is a solid which is a good conductor of electricity. State one other property of platinum which makes it suitable for use as electrodes. ........................................................................................................................................... ........................................................................................................................................... [1] (b) State what would be seen at the positive electrode during this electrolysis. ........................................................................................................................................... ........................................................................................................................................... [1] (c) State and explain what would happen to the mass of the negative electrode during this electrolysis. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... [2] 7 (d) The concentrated aqueous copper(II) chloride electrolyte is green. Suggest what would happen to the colour of the electrolyte during this electrolysis. Explain your answer. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... [2] (e) Identify the species that is oxidised during this electrolysis. Explain your answer. species that is oxidised ..................................................................................................... explanation ....................................................................................................................... ........................................................................................................................................... [2] [Total: 8] 9 Aqueous potassium iodide reacts with aqueous copper(II) sulfate to produce iodine. (a) Balance the chemical equation for this reaction. KI + CuSO4 → CuI + I2 + K2SO4 [2] (b) Deduce the charge on the copper ion in CuI. ........................................................................................................................................... [1] (c) In terms of electron transfer, explain why copper is reduced in this reaction. ........................................................................................................................................... [1] (d) Identify the reducing agent. ........................................................................................................................................... [1] [Total: 5] 10 When aqueous sodium hydroxide is added to aqueous iron(II) sulfate, a precipitate forms. (a) What colour is this precipitate? ........................................................................................................................................... [1] (b) Write the ionic equation for this reaction. Include state symbols. ........................................................................................................................................... [3] [Total: 4] 8 11 Aqueous sodium hydroxide, aqueous potassium iodide and aqueous acidified potassium manganate(VII) are added to aqueous solutions of iron(II) sulfate and iron(III) sulfate. 2+ ● Iron(II) ions, Fe , are reducing agents in aqueous solution. 3+ ● Iron(III) ions, Fe , are oxidising agents in aqueous solution. Complete the table. reagent observations with aqueous iron(II) sulfate aqueous sodium hydroxide green precipitate observations with aqueous iron(III) sulfate aqueous potassium iodide aqueous acidified potassium manganate(VII) no change [4] [Total: 4] 12 Iron can be obtained by heating iron(III) oxide with zinc powder. Fe2O3 + 3Zn → 2Fe + 3ZnO (a) What can be deduced about the reactivity of zinc from this reaction? ........................................................................................................................................... [1] (b) The ionic equation for this reaction is shown. 3+ 2Fe 2+ + 3Zn → 2Fe + 3Zn Identify the oxidising agent in this reaction. Explain your answer in terms of electron transfer. oxidising agent .................................................................................................................. explanation ....................................................................................................................... ........................................................................................................................................... [2] [Total: 3]
