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November 2021: Paper 1, Periodic table, elements and physical chemistry

100 marks · 55 question parts · Paper, mark scheme and report on OCR's site · An autumn series, sat in place of the cancelled summer exams · Have OCR's Data Sheet beside you

Question by question

QTopicMarksAOType
1 Bonding, structure and shapes of molecules 1Multiple choice
2 Redox and oxidation numbers 1Multiple choice
3 Formulae and equations, Redox titrations and electrode potentials 1Multiple choice
4 Amount of substance (moles) 1Multiple choice
5 Amount of substance (moles), Formulae and equations 1Multiple choice
6 Amount of substance (moles) 1Multiple choice
7 Periodicity and ionisation energy 1Multiple choice
8 Enthalpy changes and Hess’ law 1Multiple choice
9 Chemical equilibrium and Kc, Equilibrium constants Kc and Kp 1Multiple choice
10 Acids, bases, pH and buffers 1Multiple choice
11 Entropy and free energy 1Multiple choice
12 Redox titrations and electrode potentials 1Multiple choice
13 The halogens, Bonding, structure and shapes of molecules 1Multiple choice
14 Bonding, structure and shapes of molecules 1Multiple choice
15 Qualitative analysis: tests for ions, Transition elements 1Multiple choice
16(a) Periodicity and ionisation energy 3Short answer
16(b)(i) Periodicity and ionisation energy 1AO1Equation writing
16(b)(ii) Periodicity and ionisation energy 1AO1Short answer
16(b)(iii) Electron structure and orbitals 1AO2Complete table/diagram
16(c)(i) Lattice enthalpy and Born–Haber cycles 1AO1Short answer
16(c)(ii) Lattice enthalpy and Born–Haber cycles 2AO2Short answer
16(c)(iii) Lattice enthalpy and Born–Haber cycles 1AO2Calculation
16(c)(iv) Lattice enthalpy and Born–Haber cycles 4AO1, 3Short answer
17(a) Transition elements, Periodicity and ionisation energy 4AO1Short answer
17(b)(i) Transition elements 1AO1Short answer
17(b)(ii) Amount of substance (moles), Transition elements 6AO2, 3Level of response
18(a) Acids, bases and titrations, Formulae and equations 2AO1, 2Equation writing
18(b) Transition elements, Redox titrations and electrode potentials 1AO2Equation writing
18(c) Redox titrations and electrode potentials 1AO1Short answer
18(d) Redox titrations and electrode potentials, Amount of substance (moles) 4AO2Calculation
18(e)(i) Practical skills: planning, analysis and evaluation 1AO3Short answer
18(e)(ii) Practical skills: planning, analysis and evaluation 1AO3Short answer
18(f) Practical skills: planning, analysis and evaluation, Acids, bases and titrations 2AO3Short answer
19(a)(i) Redox titrations and electrode potentials 3AO1Drawing / labelling
19(a)(ii) Redox titrations and electrode potentials 1AO2Equation writing
19(b)(i) Redox and oxidation numbers, The halogens 2AO2Short answer
19(b)(ii) Redox titrations and electrode potentials 2AO3Data interpretation
19(c)(i) Redox titrations and electrode potentials 1AO2Equation writing
19(c)(ii) Redox titrations and electrode potentials 1AO1Calculation
19(c)(iii) Redox titrations and electrode potentials 1AO1Short answer
20(a) Chemical equilibrium and Kc 1AO1Short answer
20(b)(i) Entropy and free energy 2AO2Short answer
20(b)(ii) Entropy and free energy 1AO2Calculation
20(c)(i) Equilibrium constants Kc and Kp 4AO2Calculation
20(c)(ii) Equilibrium constants Kc and Kp, Reaction rates and the Boltzmann distribution, Chemical equilibrium and Kc 3AO1Complete table/diagram
21(a)(i) Rates: orders, rate equations and the Arrhenius equation 2AO3Short answer
21(a)(ii) Rates: orders, rate equations and the Arrhenius equation 2AO3Short answer
21(b)(i) Rates: orders, rate equations and the Arrhenius equation 3AO2Calculation
21(b)(ii) Rates: orders, rate equations and the Arrhenius equation 1AO3Short answer
21(b)(iii) Rates: orders, rate equations and the Arrhenius equation 2AO3Calculation
22(a) Acids, bases, pH and buffers 2AO2Calculation
22(b)(i) Amount of substance (moles) 2AO2Short answer
22(b)(ii) Enthalpy changes and Hess’ law 4AO2Calculation
22(b)(iii) Enthalpy changes and Hess’ law 2AO3Short answer
22(c) Acids, bases, pH and buffers, Amount of substance (moles) 6AO1, 2, 3Level of response

The questions

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November 2021 · Paper 1 · Q1 1 mark Multiple choice bonding and structure
1 Which statement describes electronegativity? A A measure of the reactivity of an element. B The ability of an atom to attract an electron to become a 1– ion. C The attraction of a bonded atom for the electrons in a covalent bond. D The attraction of an atom for a lone pair of electrons. Your answer [1]
November 2021 · Paper 1 · Q2 1 mark Multiple choice redox
2 A chlorate(VII) ion has a 1– charge. What is the formula for sodium chlorate(VII)? A NaCl O3 B NaCl O4 C NaCl O7 D NaCl O8 Your answer [1]
November 2021 · Paper 1 · Q3 1 mark Multiple choice formulae and equationsredox and electrode potentials
3 The unbalanced equation for the reaction of silver with concentrated nitric acid is shown below. ….. Ag(s) + ….. NO3 –(aq) + ….. H+(aq) → ….. Ag+(aq) + .…. NO(g) + ..… H2O(l) Which numbers for Ag and H2O will balance the equation? Ag(s) H2O(l) A 1 2 B 2 3 C 3 1 D 3 2 Your answer [1]
November 2021 · Paper 1 · Q4 1 mark Multiple choice amount of substance
4 Which sample contains the greatest number of molecules? A 140.0 g C2H2 B 180.0 g C2H6 C 240.0 g C4H10 D 400.0 g C6H6 Your answer [1]
November 2021 · Paper 1 · Q5 1 mark Multiple choice amount of substanceformulae and equations
5 Chromium(III) oxide, Cr2O3, is reduced to chromium by heating with magnesium. What is the minimum mass of Mg required to reduce 11.4 g of chromium(III) oxide? A 0.61 g B 0.91 g C 3.65 g D 5.47 g Your answer [1]
November 2021 · Paper 1 · Q6 1 mark Multiple choice amount of substance
6 A student is supplied with 100.0 cm3 of a solution of 0.400 mol dm–3 magnesium iodide, MgI2. A student plans to dilute this solution so that the iodide concentration is 0.250 mol dm–3. What volume of water, in cm3, does the student need to add? A 60.0 B 160.0 C 220.0 D 320.0 Your answer [1]
November 2021 · Paper 1 · Q7 1 mark Multiple choice periodicity
7 Which row shows elements in order of increasing first ionisation energy? A Ca < Si < P < N B N < P < Si < Ca C Ca < N < P <Si D C < Si < P < Ca Your answer [1]
November 2021 · Paper 1 · Q8 1 mark Multiple choice enthalpy changes
8 Bond enthalpies are given in the table. Bond H–S O=O S=O O–H Bond enthalpy +346 +498 +531 +464 / kJ mol–1 What is the enthalpy change, in kJ mol–1, for the reaction below? 2H2S(g) + 3O2(g) → 2SO2(g) + 2H2O(g) A –174 B –1102 C –1794 D –2098 Your answer [1]
November 2021 · Paper 1 · Q9 1 mark Multiple choice chemical equilibriumequilibrium constants
9 An equilibrium system is shown below. CO(g) + NO2(g) CO2(g) + NO(g) Different amounts of CO, NO2, CO2 and NO are added to four containers, as shown below. Container CO / mol NO2 / mol CO2 / mol NO / mol A 1 1 0 0 B 1 0 1 1 C 1 1 1 0 D 0 1 1 1 Which container would have the largest concentration of CO(g) at equilibrium? Your answer [1]
November 2021 · Paper 1 · Q10 1 mark Multiple choice acids bases and buffers
10 An aqueous solution of ethanoic acid, CH3COOH, has a concentration of 0.50 mol dm–3. pKa for CH3COOH = 4.76 at 25 °C. What is the pH of the ethanoic acid solution at 25 °C? A 2.53 B 2.68 C 4.91 D 5.06 Your answer [1]
November 2021 · Paper 1 · Q11 1 mark Multiple choice entropy and free energy
11 The feasibility of a chemical reaction depends on the temperature and the signs of ΔH and ΔS. Which row has signs for ΔH and ΔS for a reaction that is feasible at high temperatures but is not feasible at low temperatures? ΔH ΔS A + + B + – C – + D – – Your answer [1]
November 2021 · Paper 1 · Q12 1 mark Multiple choice redox and electrode potentials
12 Two redox systems are shown below. Fe2+(aq) + 2e– Fe(s) E o– = –0.44 V Cu2+(aq) + 2e– Cu(s) E o– = +0.34 V Which species in the two redox systems is the strongest oxidising agent? A Fe2+(aq) B Fe(s) C Cu2+(aq) D Cu(s) Your answer [1]
November 2021 · Paper 1 · Q13 1 mark Multiple choice halogensbonding and structure
13 Which statement(s) explain(s) the trend in boiling points down the halogens group? 1: The induced dipole–dipole interactions (London forces) become stronger. 2: The covalent bonds become stronger. 3: The permanent dipole–dipole interactions become stronger. A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
November 2021 · Paper 1 · Q14 1 mark Multiple choice bonding and structure
14 Which statement(s) about a molecule of Cl–N=O is/are correct? 1: It is a polar molecule. 2: It contains 6 lone pairs of electrons. 3: It has a bond angle of 180°. A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
November 2021 · Paper 1 · Q15 1 mark Multiple choice qualitative analysistransition elements
15 NH4Fe(SO4)2•12H2O is a hydrated ‘double salt’. A student analyses this double salt using test tube tests. Which row(s) gives/give correct result(s) for the stated test? Test Results 1 Reaction with cold NaOH(aq) Green precipitate 2 Reaction with Ba(NO3)2(aq) White precipitate 3 Reaction with warm NaOH(aq) Red-brown precipitate and an alkaline gas A 1, 2 and 3 B Only 1 and 2 C Only 2 and 3 D Only 1 Your answer [1]
November 2021 · Paper 1 · Q16(a) 3 marks Short answer periodicity
SECTION B Answer all the questions. 16 This question is about magnesium and magnesium halides. (a) Magnesium has metallic bonding and is a good conductor of electricity. Describe, with the aid of a labelled diagram, the metallic bonding in magnesium and explain why magnesium conducts electricity. Include the correct charges on the particles in your diagram. ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [3]
November 2021 · Paper 1 · Q16(b)(i) 1 mark AO1 Equation writing periodicity
(b) The 12 successive ionisation energies of magnesium are shown in Table 16.1. Ionisation Ionisation energy / kJ mol–1 number 1 738 2 1451 3 7733 4 10 541 5 13 629 6 17 995 7 21 704 8 25 657 9 31 644 10 35 463 11 169 996 12 189 371 Table 16.1 (i) Write an equation to represent the fourth ionisation energy of magnesium. Include state symbols. ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q16(b)(ii) 1 mark AO1 Short answer periodicity
Earlier part of question 16 that this part usesEarlier part of November 2021 Paper 1 question 16
(ii) Explain how the successive ionisation energies provide evidence that magnesium is in Group 2 of the periodic table. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q16(b)(iii) 1 mark AO2 Complete table/diagram electron structure
Earlier part of question 16 that this part usesEarlier part of November 2021 Paper 1 question 16
(iii) Electrons occupy orbitals. In Table 16.2 below, add a tick (✓) below the ionisation numbers that are responsible for removing an electron from a full orbital in a magnesium atom. Ionisation 1 2 3 4 5 6 7 8 9 10 11 12 number Table 16.2 [1]
November 2021 · Paper 1 · Q16(c)(i) 1 mark AO1 Short answer lattice enthalpy
(c) The enthalpy change of solution for magnesium fluoride, MgF2, can be determined indirectly using an energy cycle based on the enthalpy changes below. Enthalpy change Energy / kJ mol–1 Lattice enthalpy of magnesium fluoride –2926 Hydration of magnesium ions –1920 Hydration of fluoride ions –506 (i) Explain what is meant by enthalpy change of solution. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q16(c)(ii) 2 marks AO2 Short answer lattice enthalpy
Earlier part of question 16 that this part usesEarlier part of November 2021 Paper 1 question 16
(ii) On the dotted lines, add the species present, including state symbols. Mg2+(g) + 2F–(g) .................................................... MgF2(s) .................................................... [2]
November 2021 · Paper 1 · Q16(c)(iii) 1 mark AO2 Calculation Medium lattice enthalpy
Earlier parts of question 16 that this part usesEarlier part of November 2021 Paper 1 question 16Earlier part of November 2021 Paper 1 question 16
(iii) Calculate the enthalpy change of solution of MgF2. enthalpy change of solution = ............................................ kJ mol–1 [1]
November 2021 · Paper 1 · Q16(c)(iv) 4 marks AO1, 3 Short answer Medium lattice enthalpy
Earlier part of question 16 that this part usesEarlier part of November 2021 Paper 1 question 16
(iv) The enthalpy changes of solution of the magnesium halides show a trend from MgF2 to MgI2. Explain why it is difficult to predict whether the enthalpy change of solution becomes more exothermic or less exothermic down the group from MgF2 to MgI2. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [4]
November 2021 · Paper 1 · Q17(a) 4 marks AO1 Short answer Medium transition elementsperiodicity
17 This question is about d-block elements. (a) Most d-block elements are also classified as transition elements. Explain why scandium and zinc are classified as d-block elements but are not also transition elements. Your explanations should include full electron configurations. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [4]
November 2021 · Paper 1 · Q17(b)(i) 1 mark AO1 Short answer transition elements
(b) Compound A is a hydrated chromium(III) salt with a molar mass of 608.3 g mol–1 and the following percentage composition by mass: Cr, 17.10%; H, 3.94%; O, 63.13%; S, 15.83%. A student dissolves compound A in water. The resulting solution contains the complex ion [Cr(H2O)6]3+. The student mixes this solution with aqueous sodium ethanedioate, Na2C2O4. A ligand substitution reaction takes place forming a solution containing three stereoisomers of a complex ion B of chromium(III). Complex ion B is six-coordinate and contains two ethanedioate ligands and two water ligands. The ethanedioate ion is the bidentate ligand shown below. O O –O O– Ethanedioate ligand (i) What is meant by a bidentate ligand? ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q17(b)(ii) 6 marks AO2, 3 6-mark level of response amount of substancetransition elements
Earlier part of question 17 that this part usesEarlier part of November 2021 Paper 1 question 17
(ii)* Determine the formulae of A and B. Write the ionic equation for the ligand substitution and show 3D structures for the three stereoisomers of B. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [6] Additional answer space if required. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...........................................................................................................................................
November 2021 · Paper 1 · Q18(a) 2 marks AO1, 2 Equation writing acids and titrationsformulae and equations
18 A student carries out an experiment to determine the percentage by mass of copper in an ore containing copper in its +2 oxidation state. The student is provided with a sample of the copper ore, 1 mol dm–3 potassium iodide, KI(aq), and 0.0200 mol dm–3 sodium thiosulfate, Na2S2O3. The student’s method is outlined below. Step 1 Add an excess of warm nitric acid to 2.50 g of the ore. The copper(II) compounds in the ore react, forming aqueous copper(II) nitrate. Step 2 Filter the mixture to remove the unreacted rock. Neutralise the filtrate. Step 3 Add an excess of aqueous potassium iodide, KI(aq). A precipitate of copper(I) iodide and a solution of iodine, I2(aq), forms. Step 4 Titrate the mixture from Step 3 using 0.0200 mol dm–3 sodium thiosulfate, Na2S2O3 in the burette. I2(aq) + 2S2O3 2–(aq) → 2I–(aq) + S4O6 2–(aq) 26.55 cm3 of 0.0200 mol dm–3 Na2S2O3 are required to reach the end point. (a) In Step 1, the student observed that bubbles of gas were produced. Suggest the formula of the copper(II) compound which reacted with HNO3 to form the gas, and write a full equation for the reaction. Formula: .................................................................................................................................... Equation: .............................................................................................................................. [2]
November 2021 · Paper 1 · Q18(b) 1 mark AO2 Equation writing transition elementsredox and electrode potentials
Earlier part of question 18 that this part usesEarlier part of November 2021 Paper 1 question 18
(b) Write an ionic equation, including state symbols, for the reaction in Step 3. .............................................................................................................................................. [1]
November 2021 · Paper 1 · Q18(c) 1 mark AO1 Short answer redox and electrode potentials
Earlier part of question 18 that this part usesEarlier part of November 2021 Paper 1 question 18
(c) Suggest a suitable indicator for this titration and state the colour change at the end point in Step 4. Indicator: ................................................................................................................................... Colour from ................................................ to ..................................................................... [1]
November 2021 · Paper 1 · Q18(d) 4 marks AO2 Calculation Medium redox and electrode potentialsamount of substance
Earlier parts of question 18 that this part usesEarlier part of November 2021 Paper 1 question 18Earlier part of November 2021 Paper 1 question 18
(d) Determine the percentage, by mass, of copper in the copper ore. Give your answer to an appropriate number of significant figures. percentage = ..................................................... % [4]
November 2021 · Paper 1 · Q18(e)(i) 1 mark AO3 Short answer practical skills
Earlier part of question 18 that this part usesEarlier part of November 2021 Paper 1 question 18
(e) Explain whether the calculated percentage by mass of copper would be higher, lower or the same if the following changes were made to the method. (i) The potassium iodide was not in excess, in Step 3. ........................................................................................................................................... ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q18(e)(ii) 1 mark AO3 Short answer practical skills
Earlier part of question 18 that this part usesEarlier part of November 2021 Paper 1 question 18
(ii) The burette readings were read from the top of the meniscus, in Step 4. ........................................................................................................................................... ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q18(f) 2 marks AO3 Short answer practical skillsacids and titrations
Earlier part of question 18 that this part usesEarlier part of November 2021 Paper 1 question 18
(f) The student then modifies the method in order to obtain a more accurate value for the percentage by mass of copper in the ore. The student decides to use 25.00 g of the copper ore in Step 1. What further modifications should the student make to produce a more accurate value for the percentage by mass of copper in the ore? ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2]
November 2021 · Paper 1 · Q19(a)(i) 3 marks AO1 Drawing / labelling Medium redox and electrode potentials
19 Storage cells and fuels cells are types of electrochemical cell. The electrode potentials for five redox systems are shown in Table 19.1. Redox Half-equation E – ө – / V system 1 Cr3+(aq) + 3e– Cr(s) –0.74 2 O2(g) + 2H2O(l) + 4e– 4OH–(aq) +0.40 3 MnO4 –(aq) + e– MnO4 2–(aq) +0.56 4 MnO4 –(aq) + 8H+ (aq) + 5e– Mn2+(aq) + 4H2O(l) +1.51 5 MnO4 2–(aq) + 4H+(aq) + 2e– MnO2(s) + 2H2O(l) +1.70 Table 19.1 (a) A student sets up an electrochemical cell based on redox systems 1 and 4 in Table 19.1. (i) Draw a labelled diagram to show how this cell could be set up in the laboratory. [3]
November 2021 · Paper 1 · Q19(a)(ii) 1 mark AO2 Equation writing redox and electrode potentials
Earlier part of question 19 that this part usesEarlier part of November 2021 Paper 1 question 19
(ii) Construct the equation for the overall cell reaction. ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q19(b)(i) 2 marks AO2 Short answer redoxhalogens
Earlier part of question 19 that this part usesEarlier part of November 2021 Paper 1 question 19
(b) In acid conditions, MnO4 2–(aq) disproportionates to form MnO2(s) and MnO4 –(aq). (i) Explain, in terms of oxidation numbers, why disproportionation has taken place. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
November 2021 · Paper 1 · Q19(b)(ii) 2 marks AO3 Data interpretation Hard redox and electrode potentials
Earlier parts of question 19 that this part usesEarlier part of November 2021 Paper 1 question 19Earlier part of November 2021 Paper 1 question 19
(ii) Explain, in terms of electrode potentials and equilibrium shifts why MnO4 2–(aq) disproportionates in acid conditions. Use the information in Table 19.1. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
November 2021 · Paper 1 · Q19(c)(i) 1 mark AO2 Equation writing redox and electrode potentials
Earlier part of question 19 that this part usesEarlier part of November 2021 Paper 1 question 19
(c) An alkaline hydrogen-oxygen fuel cell is set up. The overall equation for the cell reaction is shown below. 2H2(g) + O2(g) → 2H2O(l) Redox system 2 in Table 19.1 is the positive electrode of this cell. (i) Write the half-equation at the negative electrode. ........................................................................................................................................... ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q19(c)(ii) 1 mark AO1 Calculation redox and electrode potentials
Earlier parts of question 19 that this part usesEarlier part of November 2021 Paper 1 question 19Earlier part of November 2021 Paper 1 question 19
(ii) The cell potential is 1.23 V. Calculate the electrode potential of the negative electrode. electrode potential = .................... V [1]
November 2021 · Paper 1 · Q19(c)(iii) 1 mark AO1 Short answer redox and electrode potentials
(iii) State one important feature of a fuel cell that is different from a conventional storage cell. ........................................................................................................................................... ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q20(a) 1 mark AO1 Short answer chemical equilibrium
20 This question is about chemical equilibrium. Nitrogen monoxide, NO, and oxygen, O2, react to form nitrogen dioxide, NO2, in the reversible reaction shown in Equilibrium 20.1. Equilibrium 20.1 2NO(g) + O2(g) 2NO2(g) ΔH = –114 kJ mol–1 ΔS = –147 J mol–1 K–1 (a) A dynamic equilibrium exists in a closed system. State one other feature of a dynamic equilibrium. ................................................................................................................................................... .............................................................................................................................................. [1]
November 2021 · Paper 1 · Q20(b)(i) 2 marks AO2 Short answer entropy and free energy
Earlier part of question 20 that this part usesEarlier part of November 2021 Paper 1 question 20
(b) (i) Show that the formation of NO2 in Equilibrium 20.1 is feasible at 25 °C. [2]
November 2021 · Paper 1 · Q20(b)(ii) 1 mark AO2 Calculation entropy and free energy
Earlier parts of question 20 that this part usesEarlier part of November 2021 Paper 1 question 20Earlier part of November 2021 Paper 1 question 20
(ii) Determine the maximum temperature, in K, for feasibility. Give your answer to an appropriate number of significant figures. maximum temperature = .................... K [1]
November 2021 · Paper 1 · Q20(c)(i) 4 marks AO2 Calculation Medium equilibrium constants
Earlier part of question 20 that this part usesEarlier part of November 2021 Paper 1 question 20
(c) A chemist investigates the equilibrium shown in Equilibrium 20.1. The chemist mixes together 1.60 mol of NO(g) and 1.50 mol of O2(g) in a container and the mixture is allowed to reach equilibrium. At equilibrium: • 75% of the NO(g) has been converted to NO2(g) • the total pressure is 1.21 MPa. (i) Calculate Kp, in MPa–1, for Equilibrium 20.1. Give your answer to 3 significant figures. Kp = .............................................. MPa–1 [4]
November 2021 · Paper 1 · Q20(c)(ii) 3 marks AO1 Complete table/diagram Medium equilibrium constantsreaction rateschemical equilibrium
Earlier parts of question 20 that this part usesEarlier part of November 2021 Paper 1 question 20Earlier part of November 2021 Paper 1 question 20
(ii) The chemist then repeats the experiment three times. In each experiment, the chemist makes one change but uses the same initial amounts of NO and O2. Complete the table to show the predicted effect of each change compared with the original experiment. Only use the words greater, smaller or same. Equilibrium amount Change Kp Initial rate of NO2(g) Temperature increase Pressure increase Catalyst added [3]
November 2021 · Paper 1 · Q21(a)(i) 2 marks AO3 Short answer Medium rate equations
21 This question is about how the rate of reaction is affected by changes in conditions. A student carries out two investigations using the reaction between aqueous thiosulfate ions, S2O3 2–(aq), and aqueous hydrogen ions, H+(aq). Reaction 21.1 S2O3 2–(aq) + 2H+(aq) → S(s) + SO2(g) + H2O(l) (a) In Investigation 1, the student determines how the rate of Reaction 21.1 is affected by changes in concentration. The results are shown in the table. Experiment [S2O3 2–(aq)] [H+(aq)] initial rate / mol dm–3 / mol dm–3 / mol dm–3 s–1 1 0.16 1.00 0.0120 2 0.08 1.00 0.0060 3 0.02 0.50 0.0015 From the results, the student concludes that the rate equation is rate = k [S2O3 2–(aq)] (i) Explain how the student’s results support this rate equation. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
November 2021 · Paper 1 · Q21(a)(ii) 2 marks AO3 Short answer rate equations
Earlier part of question 21 that this part usesEarlier part of November 2021 Paper 1 question 21
(ii) Predict a possible two-step mechanism for Reaction 21.1. The first step is the rate-determining step. Step 1 ............................................................................................................................... Step 2 .......................................................................................................................... [2]
November 2021 · Paper 1 · Q21(b)(i) 3 marks AO2 Calculation Medium rate equations
Earlier part of question 21 that this part usesEarlier part of November 2021 Paper 1 question 21
(b) In Investigation 2 the student determines the rate constant k of Reaction 21.1 at different temperatures, T. From the results, the student plots a graph of ln k against 1 / T as shown below. 1 / T / 10–3 K–1 3.00 3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45 –1.50 –2.00 –2.50 In k –3.00 –3.50 – 4.00 – 4.50 Graph 21.2 (i) Calculate the activation energy, Ea, for Reaction 21.1, in kJ mol–1. Give your answer to 3 significant figures. Ea = ............................................ kJ mol–1 [3]
November 2021 · Paper 1 · Q21(b)(ii) 1 mark AO3 Short answer rate equations
Earlier part of question 21 that this part usesEarlier part of November 2021 Paper 1 question 21
(ii) From the graph the student estimates the value of ln A as –2.00. (A is the pre-exponential factor.) Explain what mistake the student has made. ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [1]
November 2021 · Paper 1 · Q21(b)(iii) 2 marks AO3 Calculation rate equations
Earlier parts of question 21 that this part usesEarlier part of November 2021 Paper 1 question 21Earlier part of November 2021 Paper 1 question 21
(iii) The student calculates the value of k in Investigation 1 as 0.075 s–1. Using Graph 21.2, determine the temperature, in °C, at which Investigation 1 was carried out. temperature = .................................................... °C [2]
November 2021 · Paper 1 · Q22(a) 2 marks AO2 Calculation acids bases and buffers
22 This question is about acids, bases and buffers. (a) Sodium hydroxide, NaOH, is a strong base. Calculate the pH of 0.140 mol dm–3 NaOH(aq) at 298 K. Give your answer to 2 decimal places. pH = ......................................................... [2]
November 2021 · Paper 1 · Q22(b)(i) 2 marks AO2 Short answer amount of substance
(b) Sulfuric acid reacts with sodium hydroxide as shown in Equation 22.1. Equation 22.1 H2SO4(aq) + 2NaOH(aq) → Na2SO4(aq) + 2H2O(l) ΔH1 This is a neutralisation reaction. A student carries out an experiment to determine the enthalpy change ΔH1 and uses this value to deduce the enthalpy change of neutralisation, ΔneutH . The student measures out two solutions: • 25.0 cm3 of 1.60 mol dm–3 H2SO4(aq) • 55.0 cm3 of 1.50 mol dm–3 NaOH(aq) (an excess). The temperature of each solution is the same. The student mixes the two solutions. The temperature increases by 13.0 °C. (i) Show that NaOH is in excess. [2]
November 2021 · Paper 1 · Q22(b)(ii) 4 marks AO2 Calculation Medium enthalpy changes
Earlier part of question 22 that this part usesEarlier part of November 2021 Paper 1 question 22
(ii) Calculate the enthalpy change, ΔH1, for Equation 22.1, and deduce the value for the enthalpy change of neutralisation, ∆neutH, in kJ mol–1. Assume that the densities of all solutions and the specific heat capacity, c, of the reaction mixture are the same as for water. enthalpy change, ΔH1 = ........................................... kJ mol–1 enthalpy change of neutralisation, ΔneutH = ............................................ kJ mol–1 [4]
November 2021 · Paper 1 · Q22(b)(iii) 2 marks AO3 Short answer enthalpy changes
Earlier parts of question 22 that this part usesEarlier part of November 2021 Paper 1 question 22Earlier part of November 2021 Paper 1 question 22
(iii) The student repeats the experiment using 50.0 cm3 of 1.60 mol dm–3 H2SO4 and 110.0 cm3 of 1.50 mol dm–3 NaOH. Predict the increase in temperature. Explain your reasoning. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2]
November 2021 · Paper 1 · Q22(c) 6 marks AO1, 2, 3 6-mark level of response acids bases and buffersamount of substance
(c)* Nitrous acid, HNO2, is a weak Brønsted–Lowry acid with a pKa value of 3.34 at room temperature. HNO2 can be prepared by reacting N2O3 with water. HNO2 is the only product. A chemist makes up a buffer solution by the following method. Step 1 The chemist weighs a sample of N2O3. Water is then added to form 100 cm3 of 0.500 mol dm–3 HNO2(aq). Step 2 The chemist adds 100 cm3 of 0.150 mol dm–3 NaOH(aq) to the 100 cm3 solution of 0.500 mol dm–3 solution of HNO2(aq). The resulting solution is made up to 1.00 dm3. Explain why a buffer solution forms in Step 2. Determine the pH of this buffer solution and the mass of N2O3 that was used in Step 1. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [6] Additional answer space if required. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................

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