Physical Sciences Grade 11 P2 2020 QP (Eng)

NATIONAL SENIOR CERTIFICATE GRADE 11 NOVEMBER 2020 PHYSICAL SCIENCES P2 (CHEMISTRY) EXEMPLAR MARKS: 150 TIME: 3 hours This question paper consists of 18 pages, including 4 data sheets.

2 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) INSTRUCTIONS AND INFORMATION 1. Write your full NAME and SURNAME in the appropriate spaces on the ANSWER BOOK. 2. This question paper consists of TEN questions. Answer ALL the questions in the ANSWER BOOK. 3. Start EACH question on a NEW page in the ANSWER BOOK. 4. Number the answers correctly according to the numbering system used in this question paper. 5. Leave ONE line between two subquestions, for example between QUESTION 2.1 and QUESTION 2.2. 6. You may use a non-programmable calculator. 7. You may use appropriate mathematical instruments. 8. Show ALL formulae and substitutions in ALL calculations. 9. Round off your FINAL numerical answers to a minimum of TWO decimal places. 10. Give brief motivations, discussions, et cetera where required 11. You are advised to use the attached DATA SHEETS. 12. Write neatly and legibly. Copyright reserved Please turn over

(EC/NOVEMBER 2020) PHYSICAL SCIENCES P2 3 QUESTION 1: MULTIPLE-CHOICE QUESTIONS Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A−D), next to the question numbers (1.1 to 1.10) in the ANSWER BOOK, for example 1.11 D. 1.1 The distance between the nuclei of two adjacent atoms when atoms bond is called … A bond length. B bond energy. C interatomic bond. D intermolecular forces. (2) 1.2 Which ONE of the following substances has ION-DIPOLE forces? A H2O (ℓ) B CO2 (g) C NaCℓ (aq) D NaCℓ (s) (2) 1.3 The geometrical shape of the PCℓ5 molecule according to VSEPR theory is … A linear. B trigonal planar. C tetrahedral. D trigonal bipyramidal. (2) 1.4 ONE mole of water (H2O) and ONE mole of carbon dioxide (CO2) will have the same… A mass. B molar mass. C number of molecules. D density. (2) Copyright reserved Please turn over

4 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) 1.5 A certain mass of oxygen is sealed in a syringe. The gas exerts a pressure p. If both the volume and the temperature are doubled, the new pressure of the gas will be … A p B ଵ p ଶ C 2p D 4p (2) 1.6 The relationship between pressure and volume of a fixed amount of gas at constant temperature is BEST described by … A B P P V V C D P P V (2) 1.7 Equal masses of each of the following gases He, O2, CH4 and N2 are placed in separate containers at the same temperature and pressure. Which ONE of the gases will have the LARGEST volume? A He B O2 C CH4 D N2 (2) Copyright reserved Please turn over

(EC/NOVEMBER 2020) PHYSICAL SCIENCES P2 5 1.8 Consider the reaction: NH3 (aq) + X → NH4+ (aq) + OH (aq) X represents … A H2O acting as an acid. B H2O acting as a base. C H3O+ acting as an acid. D H3O+ acting as a base. (2) 1.9 Consider the pairs of reactants given below. Which ONE of the following pairs of reactants will produce a salt, water and carbon dioxide? A Zn + H2SO4 B NaOH + HCℓ C CuO + H2SO4 D Na2CO3 + HCℓ (2) 1.10 Consider the following redox reaction: Cr2O7 2-(aq) + Fe2+(aq) + H+(aq) → Cr3+(aq) + Fe3+(aq) + H2O(ℓ) The product of the reduction half reaction in the equation is … A Fe3+ B Cr3+ C H2O D H+ (2) [20] Copyright reserved Please turn over

6 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) QUESTION 2 (Start on a NEW page.) Consider the following chemical equations: I: CH4 + 2 O2 → CO2 + 2 H2O II : NH3 + H+ → NH4+ 2.1 Define the term covalent bond. (2) 2.2 Write down the Lewis structure for the CH4 molecule. (2) 2.3 Consider the bonds C – H and O – H Which bond … 2.3.1 has a longer bond length? Give a reason for your answer. (2) 2.3.2 is stronger? (1) 2.4 How many lone pairs of electrons are in the central atom of the H2O molecule? (1) 2.5 Write down the formula of a substance in reaction II that has a dative covalent bond. (1) 2.6 The NH3 molecule is POLAR but the CH4 molecule is NON-POLAR. Explain this observation. (4) [13] Copyright reserved Please turn over

(EC/NOVEMBER 2020) PHYSICAL SCIENCES P2 7 QUESTION 3 (Start on a NEW page.) 3.1 The boiling points in the table below were obtained during an investigation carried out to compare the boiling points of group 7 hydrides. The hydrides, HCℓ and HBr, are labelled in the table as compounds A and B respectively. Compound Molecular mass Boiling point (g.mol-1) (o C) A HCℓ 36,6 - 85 B HBr 81 - 66 3.1.1 Define the term boiling point. (2) 3.1.2 In what phase are compounds (A and B) at 0 °C and 101 kPa of external pressure? (1) 3.1.3 Name the type of intermolecular force that exists between molecules of both compounds A and B due to the polar nature of these molecules. (1) 3.1.4 Which ONE of the compounds (A or B), has STRONGER London forces (dispersion forces)? Give a reason for your answer. (3) 3.1.5 Which compound (A or B), will have the higher vapour pressure? Give a reason for the answer by referring to the data in the table. (2) Compound C (HF), not shown in the table, has a smaller molecular size than both compounds A and B but has a relatively higher boiling point of 19,5 °C. 3.1.6 Explain why the boiling point of compound C is HIGHER than that of compounds A and B by referring to the TYPE and STRENGTH of intermolecular forces involved. (3) 3.2 Solid iodine (I2) is added to equal volumes of carbon tetrachloride (CCℓ4) and water in separate test tubes as shown in the diagram below. CCℓ4 H2O Iodine 3.2.1 In which liquid (CCℓ4 or H2O), will the iodine dissolve? (1) 3.2.2 Explain the answer to QUESTION 3.2.1 above by referring to the intermolecular forces involved. (3) [16] Copyright reserved Please turn over

8 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) QUESTION 4 (Start on a NEW page.) Grade 11 learners want to verify the relationship between temperature and volume of a gas. They used the following experimental set-up. Apparatus X 4.1 Write down the name of the gas law that is investigated. (1) 4.2 For this investigation write down the: 4.2.1 Investigative question (2) 4.2.2 Controlled variable (1) 4.3 Write down the name of apparatus X. (1) 4.4 The learners plot the results of their investigation on the graph below: 4.4.1 Determine, by calculation, the value of X. 132 g of CO2 gas was used in the above investigation. (4) 4.4.2 Calculate the pressure of the gas at 269 K. (5) Copyright reserved Please turn over

(EC/NOVEMBER 2020) PHYSICAL SCIENCES P2 9 4.5 Write down the TWO conditions of temperature and pressure at which real gases deviate from the ideal gas behaviour. (2) 4.6 The CO2 used in the investigation is replaced with an equal amount of H2 (g). Which gas (CO2 or H2) behaves more closely to an ideal gas? Give TWO reasons for your answer. (3) [19] Copyright reserved Please turn over

10 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) QUESTION 5 (Start on a NEW page.) Learners study ENDOTHERMIC and EXOTHERMIC reactions by conducting experiments I and II in which the reactions shown in the table below take place. EXPERIMENT BALANCED EQUATION I 2 H2O2 (ℓ) → 2 H2O (ℓ) + O2(g) II 2 H2O (ℓ) → 2 H2 (g) + O2 (g) The learners measured the initial and final temperatures of the reaction mixtures. They also obtained activation energies for the reactions from a data table. The learners represented their findings in a table as shown below. EXPERIMENT Initial (°C) Final (°C) Activation energy (kJ/mol) I 24 36 75 II 24 18 237 5.1 Define the term activation energy. (2) 5.2 In which experiment (I or II) is the reaction EXOTHERMIC? Explain your answer. (2) 5.3 Is the heat of the reaction, ΔH, POSITIVE or NEGATIVE for an EXOTHERMIC reaction? (1) 5.4 Write down the general name of a substance that can be added to the reaction mixture in experiment II to reduce the activation energy. (1) 5.5 Both reactions produce the same number of moles of oxygen gas. How does the mass of H2O2 used in experiment I compare to the mass of H2O used in experiment II? Write down only SMALLER THAN, LARGER THAN or THE SAME. (2) Copyright reserved Please turn over

(EC/NOVEMBER 2020) PHYSICAL SCIENCES P2 11 5.6 Draw a potential energy versus time graph for the reaction in experiment II. The following must be shown on the graph. x Heat of the reaction (ΔH) x Activation energy (Ea) (3) [11] QUESTION 6 (Start on a NEW page.) 6.1 Methyl propanoate is an organic compound with the following percentage composition: 54,55% C ; 9,09% H ; 36,36% O The molar mass of the compound is 88 g∙mol-1. 6.1.1 Define the term empirical formula. (2) 6.1.2 Determine, by calculation, the empirical formula. (6) 6.1.3 Determine the molecular formula. (2) 6.2 Learners prepare a solution of sodium hydroxide (NaOH) in water by placing 8 g of sodium hydroxide (NaOH) in a volumetric flask and adding water to produce 250 cm3 of solution after stirring. 6.2.1 Define concentration in words. (2) 6.2.2 Calculate the concentration of the sodium hydroxide (NaOH) solution. (4) 6.3 Sodium azide (NaN3) is used in car airbags. For the airbag to inflate the following reaction must take place: 2 NaN3 (s) → 2 Na (s) + 3 N2 (g) Calculate the volume of nitrogen gas (N2) that would be produced at STP if 55 g of sodium azide reacts completely. (5) [21] Copyright reserved Please turn over

12 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) QUESTION 7 (Start on a NEW page.) The fertiliser ammonium sulphate ((NH4)2SO4) is produced from the reaction of sulphuric acid (H2SO4) and ammonia (NH3) according to the balanced equation: H2SO4 + 2 NH3 (NH4)2SO4 2 kg of sulphuric acid and 58,82 moles of ammonia are available to produce the fertiliser. 7.1 Define the term limiting reagent. (2) 7.2 Calculate the maximum mass of ammonium sulphate that can be produced by the reaction. (7) [9] QUESTION 8 (Start on a NEW page.) 8.1 Consider the chemical reaction below: HPO42 (aq) + H2O (ℓ) → PO43 (aq) + H3O+ (aq) 8.1.1 Define a base according to a Lowry-Bronsted theory. (2) 8.1.2 Write down ONE conjugate acid-base pair in the equation. (1) 8.1.3 Is the reaction mixture ACIDIC or ALKALINE at the completion of the reaction? Give a reason for your answer. (2) 8.1.4 Write down the formula of a substance in the reaction, other than H2O, that can act as an ampholyte in some reactions. (2) 8.2 Copper (II) oxide (CuO) reacts with nitric acid. Write down a balanced equation for the reaction. (3) 8.3 40 g of IMPURE calcium carbonate reacts with a 200 cm3 of a dilute sulphuric acid with a concentration of 1,5 mol∙dm-3. All the calcium carbonate and sulphuric acid react completely leaving the impurities unreacted at the completion of the reaction. CaCO3 (s) + H2SO4 (aq) → CaSO4 (s) + CO2(g) + H2O (ℓ) 8.3.1 Calculate the percentage purity of the calcium carbonate. (6) To obtain the sulphuric acid solution of concentration 1,5 mol.dm -3 that reacted with the IMPURE calcium carbonate, 10 cm 3 of a concentrated sulphuric acid solution of concentration 9 mol∙dm-3 was added to water. 8.3.2 Calculate the volume of water required to dilute the concentrated sulphuric acid solution to a concentration of 1,5 mol∙dm-3. (4) [20] Copyright reserved Please turn over

(EC/NOVEMBER 2020) PHYSICAL SCIENCES P2 13 QUESTION 9 (Start on a NEW page.) 9.1 Consider the redox reaction given below. Fe3+ + Zn → Zn2+ + Fe2+ 9.1.1 Define oxidation reaction in terms of electron transfer. (2) Write down the: 9.1.2 Formula of the reducing agent (2) 9.1.3 Reduction half reaction (2) 9.2 Consider the redox reaction below: Ag (s) + NO3 (aq) → NO2 (g) + Ag+ (aq) 9.2.1 Determine the oxidation number of nitrogen (N) in NO3 . (2) 9.2.2 Balance the above chemical equation using the ion-electron method. (4) [12] QUESTION 10 (Start on a NEW page.) 10.1 The mining industry contributes towards the South African economy. Gold is one of the minerals that is being mined in South Africa. 10.1.1 Write down the name of the location of the major mining activity in South Africa. (1) The following chemical reaction occurs during the final steps in the recovery process of gold. Zn + 2 NaAu(CN)2 → 2 Au + Zn(CN)2 + 2 NaCN 10.1.2 Is gold OXIDISED or REDUCED during the reaction? Explain the answer by referring to the oxidation number. (3) 10.1.3 The NaCN is one of the products formed in the reaction. Give a reason why chemists MUST ensure that NaCN does not find its way to nearby water sources. (2) 10.1.4 Write down the name of the process that is followed after this reaction. (1) Copyright reserved Please turn over

14 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) 10.2 The burning of fossil fuels has a negative impact on the environment. Write down TWO negative impacts of the large-scale burning of fossil fuels. (2) [9] TOTAL: 150 Copyright reserved Please turn over

(EC/NOVEMBER 2020) PHYSICAL SCIENCES P2 15 NATIONAL SENIOR CERTIFICATE NASIONALE SENIOR SERTIFIKAAT DATA FOR PHYSICAL SCIENCES GRADE 11 PAPER 2 (CHEMISTRY) GEGEWENS VIR FISIESE WETENSKAPPE GRAAD 11 VRAESTEL 2 (CHEMIE) TABLE 1: PHYSICAL CONSTANTS/TABEL 1: FISIESE KONSTANTES NAAM/NAME SIMBOOL/SYMBOL WAARDE/VALUE Standard pressure pT 1,013 × 105 Pa Standaarddruk Molar gas volume at STP Vm 22,4 dm3∙mol-1 Molêre gasvolume teen STD Standard temperature Tθ 273 K Standaardtemperatuur Charge on electron e -1,6 × 10-19 C Lading op elektron Avogadro’s constant NA 6,02 × 1023 mol-1 Avogadro se konstante TABLE 2: FORMULAE/TABEL 2: FORMULES m n m n= or/of c= or/of c = pH= -log[H3O+] M V MV Kw = [H3O+][OH-] = 1x10-14 N ca Va na at /by 298K n= or/of = NA cb Vb nb V n= Vm Eθcell = Eθcathode–Eθanode / Eθsel = Eθkatode–Eθanode Eθcell = Eθreduction–Eθoxidation / Eθsel = Eθreduksie–Eθoksidasie Eθcell = Eθoxidising agent–Eθreducing agent / Eθsel = Eθoksideermiddel–Eθreduseermiddel Copyright reserved Please turn over

16 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) TABLE 3: THE PERIODIC TABLE OF ELEMENTS/TABEL 3: DIE PERIODIEKE TABEL VAN ELEMENTE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 (I) (II) Atoomgetal (III) (IV) (V) (VI) (VII) (VIII) KEY/ SLEUTEL Atomic number 1 2 H He 2,1 29 1 4 Elektronegatiwiteit Simbool 3 4 Cu 5 6 7 8 9 10 Electronegativity 1,9 Symbol Li Be 63,5 B C N O F Ne 1,0 1,5 2,0 2,5 3,0 3,5 4,0 7 9 11 12 14 16 19 20 11 12 13 14 15 16 17 18 Na Mg Benaderde relatiewe atoommassa Aℓ Si P S Cℓ Ar 0,9 1,2 Approximate relative atomic mass 1,5 1,8 2,1 2,5 3,0 23 24 27 28 31 32 35,5 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 0,8 1,0 1,3 1,5 1,6 1,6 1,5 1,8 1,8 1,8 1,9 1,6 1,6 1,8 2,0 2,4 2,8 39 40 45 48 51 52 55 56 59 59 63,5 65 70 73 75 79 80 84 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 0,8 1,0 1,2 1,4 1,8 1,9 2,2 2,2 2,2 1,9 1,7 1,7 1,8 1,9 2,1 2,5 86 88 89 91 92 96 101 103 106 108 112 115 119 122 128 127 131 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tℓ Pb Bi Po At Rn 0,7 133 0,9137 139 1,6 179 181 184 186 190 192 195 197 201 1,8204 1,8 207 1,9 209 2,0 2,5 87 88 89 Fr Ra Ac 0,7 0,9226 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 140 141 144 150 152 157 159 163 165 167 169 173 175 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr 232 238 Copyright reserved Please turn over

(EC/NOVEMBER 2020) PHYSICAL SCIENCES P2 17 TABLE 4A: STANDARD REDUCTION POTENTIALS TABEL 4A: STANDAARD REDUKSIEPOTENSIALE Half-reactions/Halfreaksies ' Ƌ (V) F2(g) + 2e ⇌ 2F + 2,87 Co3+ + e ⇌ Co2+ + 1,81 +  H2O2 + 2H +2e ⇌ 2H2O +1,77  2+ MnO 4 + 8H+ + 5e ⇌ Mn + 4H2O + 1,51   Cℓ2(g) + 2e ⇌ 2Cℓ + 1,36 2 3+ Cr2O 7 + 14H+ + 6e ⇌ 2Cr + 7H2O + 1,33 O2(g) + 4H+ + 4e ⇌ 2H2O + 1,23 +  Mn 2+ + 2H2O + 1,23 MnO2 + 4H + 2e ⇌ Pt2+ + 2e ⇌ Pt + 1,20 Br2(ℓ) + 2e ⇌ 2Br + 1,07  NO 3 + 4H+ + 3e ⇌ NO(g) + 2H2O + 0,96 Increasing reducing ability/Toenemende reduserende vermoë Increasing oxidising ability/Toenemende oksiderende vermoë Hg2+ + 2e ⇌ Hg(ℓ) + 0,85 Ag+ + e ⇌ Ag + 0,80  NO 3 + 2H+ + e ⇌ NO2(g) + H2O + 0,80 3+  2+ Fe +e ⇌ Fe + 0,77 O2(g) + 2H+ + 2e ⇌ H2O2 + 0,68   + 0,54 I2 + 2e ⇌ 2I Cu+ + e ⇌ Cu + 0,52 SO2 + 4H+ + 4e ⇌ S + 2H2O + 0,45   2H2O + O2 + 4e ⇌ 4OH + 0,40 2+  Cu + 2e ⇌ Cu + 0,34 2 SO 4 + 4H+ + 2e ⇌ SO2(g) + 2H2O + 0,17 2+  + Cu +e ⇌ Cu + 0,16 Sn4+ + 2e ⇌ Sn2+ + 0,15 +  H2S(g) + 0,14 S + 2H + 2e ⇌ 2H+ + 2e ⇌ H2(g) 0,00 Fe3+ + 3e ⇌ Fe  0,06 Pb 2+ + 2e  ⇌ Pb  0,13 Sn2+ + 2e ⇌ Sn  0,14 Ni2+ + 2e ⇌ Ni  0,27 Co2+ + 2e ⇌ Co  0,28 Cd 2+ + 2e  ⇌ Cd  0,40 Cr3+ + e ⇌ Cr2+  0,41 Fe2+ + 2e ⇌ Fe  0,44 Cr3+ + 3e ⇌ Cr  0,74 Zn 2+ + 2e  ⇌ Zn  0,76 2H2O + 2e ⇌ H2(g) + 2OH  0,83 Cr2+ + 2e ⇌ Cr  0,91 Mn2+ + 2e ⇌ Mn  1,18 Aℓ 3+ + 3e  ⇌ Aℓ  1,66 Mg2+ + 2e ⇌ Mg  2,36 Na+ + e ⇌ Na  2,71 Ca2+ + 2e ⇌ Ca  2,87 2+ Sr + 2e  ⇌ Sr  2,89 Ba2+ + 2e ⇌ Ba  2,90 Cs+ + e- ⇌ Cs - 2,92 K+ + e ⇌ K  2,93 + Li + e  ⇌ Li  3,05 Copyright reserved Please turn over

18 PHYSICAL SCIENCES P2 (EC/NOVEMBER 2020) TABLE 4B: STANDARD REDUCTION POTENTIALS TABEL 4B: STANDAARD REDUKSIEPOTENSIALE Half-reactions/Halfreaksies ' Ƌ (V) Li+ + e ⇌ Li  3,05 K+ + e ⇌ K  2,93 Cs+ + e ⇌ Cs  2,92 Ba2+ + 2e ⇌ Ba  2,90 Sr2+ + 2e ⇌ Sr  2,89 Ca2+ + 2e ⇌ Ca  2,87 Na+ + e ⇌ Na  2,71 Mg2+ + 2e ⇌ Mg  2,36 3+ Aℓ + 3e  ⇌ Aℓ  1,66 Mn2+ + 2e ⇌ Mn  1,18 Increasing reducing ability/Toenemende reduserende vermoë Cr2+ + 2e ⇌ Cr  0,91 2H2O + 2e ⇌ H2(g) + 2OH  0,83 Increasing oxidising ability/Toenemende oksiderende vermoë Zn2+ + 2e ⇌ Zn  0,76 Cr3+ + 3e ⇌ Cr  0,74 Fe2+ + 2e ⇌ Fe  0,44 3+ Cr + e  ⇌ Cr 2+  0,41 Cd2+ + 2e ⇌ Cd  0,40 Co2+ + 2e ⇌ Co  0,28 Ni2+ + 2e ⇌ Ni  0,27 Sn2+ + 2e ⇌ Sn  0,14 2+ Pb + 2e  ⇌ Pb  0,13 Fe3+ + 3e ⇌ Fe  0,06 2H+ + 2e ⇌ H2(g) 0,00 S + 2H+ + 2e ⇌ H2S(g) + 0,14 Sn4+ + 2e ⇌ Sn2+ + 0,15  2+ Cu + e ⇌ Cu+ + 0,16 2 SO 4 + 4H+ + 2e ⇌ SO2(g) + 2H2O + 0,17 Cu2+ + 2e ⇌ Cu + 0,34 2H2O + O2 + 4e ⇌ 4OH + 0,40 SO2 + 4H+ + 4e ⇌ S + 2H2O + 0,45 Cu+ + e ⇌ Cu + 0,52   I2 + 2e ⇌ 2I + 0,54 O2(g) + 2H+ + 2e ⇌ H2O2 + 0,68 Fe3+ + e ⇌ Fe2+ + 0,77  NO 3 + 2H+ + e ⇌ NO2(g) + H2O + 0,80 Ag+ + e ⇌ Ag + 0,80 2+  Hg + 2e ⇌ Hg(ℓ) + 0,85  NO 3 + 4H+ + 3e ⇌ NO(g) + 2H2O + 0,96   Br2(ℓ) + 2e ⇌ 2Br + 1,07 Pt2+ + 2 e ⇌ Pt + 1,20 MnO2 + 4H+ + 2e ⇌ Mn2+ + 2H2O + 1,23 O2(g) + 4H+ + 4e ⇌ 2H2O + 1,23 2 Cr2O 7 + 14H+ + 6e ⇌ 2Cr3+ + 7H2O + 1,33 Cℓ2(g) + 2e ⇌ 2Cℓ + 1,36  2+ MnO 4 + 8H+ + 5e ⇌ Mn + 4H2O + 1,51 +  H2O2 + 2H +2 e ⇌ 2H2O +1,77 Co3+ + e ⇌ Co2+ + 1,81 F2(g) + 2e ⇌ 2F + 2,87 Copyright reserved Please turn over