AQA AS CHEMISTRY Paper 1 Inorganic and Physical Chemistry MAY 2023

AQA AS CHEMISTRY Paper 1 Inorganic and Physical Chemistry Tuesday 16 May 2023 Morning Time allowed: 1 hour 30 minutes Materials For this paper you must have: • the Periodic Table/Data Sheet, provided as an insert (enclosed) • a ruler with millimetre measurements • a scientific calculator, which you are expected to use where appropriate. Instructions • Use black ink or black ball-point pen. • Fill in the boxes at the top of this page. • Answer all questions. • You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • All working must be shown. • Do all rough work in this book. Cross through any work you do not want to be marked. Information • The marks for questions are shown in brackets. • The maximum mark for this paper is 80. Advice You are advised to spend about 65 minutes on Section A and 25 minutes on Section B. Section A Answer all questions in this section. box This question is about the elements in Period 3. . Give the full electron configuration of the element in Period 3 with the highest first ionisation energy. [1 mark] . Give an equation, including state symbols, to represent the process that occurs when the second ionisation energy of sodium is measured. [1 mark] . Table 1 shows some successive ionisation energies for an element in Period 3. Table 1 Ionisation number 1 2 3 4 5 6 7 8 Ionisation energy / kJ mol–1 1000 2260 3390 4540 6990 8490 27 100 31 700 Identify the Period 3 element. Explain your answer. [3 marks] Element Explanation This question is about the elements in Group 2. box . Describe the structure and bonding in magnesium. [2 marks] 0 2 . 2 State the trend in the atomic radius of the elements down Group 2 from Mg to Ba Give a reason for this trend. [2 marks] Trend Reason 0 2 . 3 Give an equation, including state symbols, for the reaction of magnesium with steam. State two observations for this reaction. [3 marks] Equation Observation 1 Observation 2 Question 2 continues on the next page Turn over ► box 0 2 . 5 A sample of strontium is made up of only three isotopes: 86Sr, 87Sr and 88Sr This sample contains 83.00% by mass of 88Sr This sample of strontium has Ar = 87.73 Calculate the percentage abundance of each of the other two isotopes in this sample. [4 marks] % abundance 87Sr = % abundance 86Sr = . Mg(OH)2 is used as an antacid to treat indigestion. A student does an experiment to determine the percentage by mass of Mg(OH)2 in an indigestion tablet. 40.0 cm3 of 0.200 mol dm–3 HCl (an excess) is added to 0.200 g of a powdered tablet. The mixture is swirled thoroughly. All of the Mg(OH)2 reacts with HCl as shown. Mg(OH)2 + 2 HCl → MgCl2 + 2 H2O The amount of HCl remaining after this reaction is determined by titration with 0.100 mol dm–3 NaOH 29.25 cm3 of 0.100 mol dm–3 NaOH are needed. box Calculate the percentage by mass of Mg(OH)2 in the indigestion tablet. [6 marks] Percentage by mass Turn over ► A student uses this method to prepare a standard solution of sodium carbonate. 1. Weigh a clean, dry, empty container on a balance that reads to 2 decimal places. 2. Add about 2.5 g of solid sodium carbonate to the container. 3. Tip the solid into a beaker. 4. Add approximately 100 cm3 of distilled water to the beaker and stir until all the solid has dissolved. 5. Pour the solution into a 250 cm3 volumetric flask. 6. Add distilled water until the top of the meniscus is level with the graduation mark. box 0 3 . 1 Suggest three improvements to this method. [3 marks] 1 2 3 . A different student uses the correct method to prepare 250 cm3 of sodium carbonate solution in a volumetric flask. The uncertainty for the volumetric flask is ±0.20 cm3 Calculate the percentage uncertainty in the volume of this sodium carbonate solution. [1 mark] Percentage uncertainty box *07* Turn over ► This question is about the shapes of molecules. Discuss the difference between the shapes of CF4 and XeF4 In your answer you should: • name the shape of each molecule • explain the shape of each molecule • explain the bond angle(s) in each molecule. [6 marks] box box Turn over ► This question is about halogens and halide ions. . Explain why the electronegativity of the halogens decreases down the group. [2 marks] box Concentrated sulfuric acid reacts with solid sodium chloride and with solid sodium bromide. 0 6 . 2 State one similarity in, and one difference between, these reactions. [2 marks] Similarity Difference 0 6 . 3 Solid sodium iodide reacts with concentrated sulfuric acid to form hydrogen sulfide. Give a half-equation to show the oxidation of iodide ions. Give a half-equation to show the reduction of concentrated sulfuric acid to hydrogen sulfide. Use your half-equations to deduce an overall equation for this reaction. [3 marks] Half-equation 1 Half-equation 2 Overall equation Turn over for the next question DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED box Turn over ► This question is about time of flight (TOF) mass spectrometry. box 0 7 . 1 Compound X is dissolved in a polar, volatile solvent and is ionised by electrospray ionisation. Each ion is accelerated so that it has a kinetic energy of 1.36 × 10 –16 J The kinetic energy of an ion is given by the equation KE = 1 mv2 2 where: KE = kinetic energy / J m = mass / kg v = speed / m s–1 The time of flight along the 0.750 m flight tube is 2.48 × 10 –5 s Determine the mass, in g, of one mole of X. The Avogadro constant, L = 6.022 × 1023 mol–1 [5 marks]