Physical Sciences Grade 12 P2 NSC June 2018 QP (Eng)

Downloaded from hlayiso.com SENIOR CERTIFICATE EXAMINATIONS PHYSICAL SCIENCES: CHEMISTRY (P2) 2018 MARKS: 150 TIME: 3 hours This question paper consists of 16 pages and 4 data sheets. Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 2 DBE/2018 SCE INSTRUCTIONS AND INFORMATION 1. Write your centre number and examination number 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. You are advised to use the attached DATA SHEETS. 9. Show ALL formulae and substitutions in ALL calculations. 10. Round off your final numerical answers to a minimum of TWO decimal places. 11. Give brief motivations, discussions, et cetera where required. 12. Write neatly and legibly. Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 3 DBE/2018 SCE QUESTION 1: MULTIPLE-CHOICE QUESTIONS Various options are provided as possible answers to the following questions. Choose the answer and write down only the letter (A–D) next to the question numbers (1.1 to 1.10) in the ANSWER BOOK, e.g. 1.11 D. 1.1 An example of a saturated organic compound is … A ethyne. B propene. C but-2-ene. D 2-chloropropane. (2) 1.2 When ethene reacts with hydrogen gas in the presence of a catalyst, the product is … A ethane. B ethyne. C ethanol. D ethanal. (2) 1.3 Study the structural formula of the functional group below. O C C C The structure above is the functional group of … A esters. B ketones. C aldehydes. D carboxylic acids. (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 4 DBE/2018 SCE 1.4 The potential energy graph for a hypothetical chemical reaction is shown below. Potential energy (kJ∙mol-1) c products b reactants a Course of reaction What type of reaction is taking place and what are the correct methods to calculate H and E a ? TYPE OF H Ea REACTION A Exothermic b−a c−b B Endothermic b−a c−a C Endothermic a−b a−c D Exothermic a−b b−c (2) 1.5 Study the hypothetical reaction below: 2P(g) + 3Q(g) → 4R(g) + 2Z(g) The rate of the reaction in terms of the number of moles of substance P used up, is 1 x 10-3 mol∙dm-3∙s-1. What is the rate (in mol∙dm-3∙s-1) at which product R is formed? A 1× 10 −3 B 4(1 × 10 −3 ) C 1× 10 −3 2 D 2(1× 10 −3 ) (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 5 DBE/2018 SCE 1.6 Study the following reaction at equilibrium at a certain temperature. 2SO 3 (g) ⇌ O 2 (g) + 2SO 2 (g) H > 0 Which ONE of the following factors will change the K c value? A Adding more SO 2 (g). B Adding a catalyst. C Increasing the temperature. D Increasing the pressure by decreasing the volume. (2) 1.7 Which ONE of the following represents the products formed during the hydrolysis of NH +4 (aq)? A NH 3 (aq) + H 2 O(ℓ) B NH 3 (aq) + H 3 O+(aq) C NH 3 (aq) + OH–(aq) D NH 3 (aq) + OH–(aq) + H 2 O(ℓ) (2) 1.8 Potassium nitrate is used as an electrolyte in the salt bridge of a copper-zinc cell. Which ONE of the following CORRECTLY shows the direction of migration of potassium and nitrate ions in the cell? POTASSIUM IONS NITRATE IONS TO THE: TO THE: A Anode Cathode B Negative electrode Positive electrode C Zinc electrode Copper electrode D Copper electrode Zinc electrode (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 6 DBE/2018 SCE 1.9 Which ONE of the following shows the electrode where the electrons are gained in an electrolytic cell and the chemical change that occurs at this electrode? ELECTRODE WHERE CHEMICAL CHANGE ELECTRONS ARE GAINED A Anode Oxidation B Anode Reduction C Cathode Oxidation D Cathode Reduction (2) 1.10 The industrial preparation of nitric acid is known as the … A Haber process. B contact process. C Ostwald process. D catalytic oxidation of ammonia. (2) [20] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 7 DBE/2018 SCE QUESTION 2 (Start on a new page.) Next to each letter, A to F, in the table below is the molecular formula of an organic compound. A C 2 H 5 Br B C2H4 C C 4 H 10 D C2H6O E C3H6O F C3H6O2 2.1 Choose a molecular formula above that represents an organic compound below. Write down only the letter (A to F) next to the question numbers (2.1.1 to 2.1.5), e.g. 2.1.6 G. 2.1.1 A haloalkane (1) 2.1.2 An alcohol (1) 2.1.3 An unsaturated hydrocarbon (1) 2.1.4 An aldehyde (1) 2.1.5 A product of thermal cracking of compound C (1) 2.2 If compound F is a carboxylic acid, write down the following: 2.2.1 The structural formula of a FUNCTIONAL isomer of F (2) 2.2.2 The IUPAC name of a FUNCTIONAL isomer of F (2) 2.3 Compound B is a monomer used to make a polymer. Write down the: 2.3.1 Definition of a polymer (2) 2.3.2 IUPAC name of the polymer (1) 2.3.3 Balanced equation for the polymerisation reaction (3) 2.4 Compound A is used as a reactant in the production of compound D. Name the type of reaction that takes place. (1) 2.5 State TWO changes that can be made to the reaction conditions in QUESTION 2.4 to obtain compound B, instead of D, as product. (2) [18] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 8 DBE/2018 SCE QUESTION 3 (Start on a new page.) The boiling points of straight-chain alkanes and straight-chain alcohols are compared in the table below. NUMBER OF BOILING POINTS BOILING POINTS OF CARBON ATOMS OF ALKANES (°C) ALCOHOLS (°C) 1 - 162 64 2 - 89 78 3 - 42 98 4 - 0,5 118 3.1 Explain the increase in boiling points of the alkanes, as indicated in the table. (3) 3.2 Explain the difference between the boiling points of an alkane and an alcohol, each having THREE carbon atoms per molecule, by referring to the TYPE of intermolecular forces. (4) 3.3 Does the vapour pressure of the alcohols INCREASE or DECREASE with an increase in the number of carbon atoms? (1) 3.4 How will the boiling point of 2-methylpropane compare to that of its chain isomer? Write down HIGHER THAN, LOWER THAN or EQUAL TO. Give a reason for the answer by referring to the structural differences between the two compounds. (2) [10] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 9 DBE/2018 SCE QUESTION 4 (Start on a new page.) Propan-1-ol can undergo a number of organic reactions, as indicated by the letters A to D in the diagram below. CH3CHCH2 Reaction D Reaction B Reaction C Reaction A CH3CH2CH2OOCCH3 Propan-1-ol CH3CH2CH2Br H2SO4 4.1 Write down the type of reaction represented by: 4.1.1 A (1) 4.1.2 B (1) 4.1.3 C (1) 4.1.4 D (1) 4.2 For reaction C, write down the: 4.2.1 Function of H 2 SO 4 (1) 4.2.2 IUPAC name of the organic product (2) 4.2.3 Structural formula of the other organic reactant (2) 4.3 Use STRUCTURAL FORMULAE for all organic reactants and products to write a balanced equation for reaction A. (5) [14] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 10 DBE/2018 SCE QUESTION 5 (Start on a new page.) Two experiments are carried out to investigate one of the factors that affects the reaction rate between magnesium and dilute hydrochloric acid. The balanced equation below represents the reaction that takes place. Mg(s) + 2HCℓ(aq) → MgCℓ 2 (aq) + H 2 (g) In experiment 1 a certain mass of magnesium ribbon reacts with excess dilute hydrochloric acid. In experiment 2 magnesium powder of the same mass as the magnesium ribbon, reacts with the same volume of excess dilute hydrochloric acid. The concentration of the acid is the same in both experiments. The apparatus below is used for the investigation. Cotton wool plug Dilute hydrochloric acid Gas bubbles Magnesium Balance 5.1 Define reaction rate. (2) 5.2 For this investigation, write down the: 5.2.1 Independent variable (1) 5.2.2 Control variable (1) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 11 DBE/2018 SCE The change in mass of magnesium is calculated and recorded in 2-minute intervals for both experiments. The results obtained are shown in the graph below (NOT drawn to scale). Mass of magnesium (g) 2,6 Exp. 1 Exp. 2 0,2 0 2 10 16 Time (minutes) 5.3 Use the information on the graph to: 5.3.1 Calculate the volume of hydrogen gas produced in experiment 1 from t = 2 minutes to t = 10 minutes Take the molar gas volume as 25 dm3∙mol-1. (5) 5.3.2 Calculate the initial mass of magnesium used if the average rate of formation of hydrogen gas in experiment 2 was 2,08 x 10-4 mol∙s-1 (5) 5.4 Use the collision theory to explain why the curve of experiment 2 is steeper than that of experiment 1. (3) [17] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 12 DBE/2018 SCE QUESTION 6 (Start on a new page.) The equation below represents a hypothetical reaction that reaches equilibrium in a closed container after 2 minutes at room temperature. The letters x, y and z represent the number of moles in the balanced equation. xA(aq) + yB(aq) ⇌ zC(aq) The graph below shows the change in the number of moles of reactants and products versus time during the reaction. Graph of number of moles of reactants and products versus time 16 Number of reactants and products (mol) C 12 A 8 B 4 0 1 2 3 4 5 6 7 8 Time (minutes) 6.1 Define a dynamic equilibrium. (2) 6.2 Use the information in the graph and write down the value of: 6.2.1 x (1) 6.2.2 y (1) 6.2.3 z (1) 6.3 Calculate the equilibrium constant, K c , for this hypothetical reaction at room temperature if the volume of the closed container is 3 dm3. (7) 6.4 At t = 4 minutes, the temperature of the system was increased to 60 °C. Is the REVERSE reaction EXOTHERMIC or ENDOTHERMIC? Explain how you arrived at the answer. (3) [15] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 13 DBE/2018 SCE QUESTION 7 (Start on a new page.) The reaction between a sulphuric acid (H 2 SO 4 ) solution and a sodium hydroxide (NaOH) solution is investigated using the apparatus illustrated below. Retort stand Burette H2SO4(aq) Erlenmeyer flask NaOH(aq) 7.1 Write down the name of the experimental procedure illustrated above. (1) 7.2 What is the function of the burette? (1) 7.3 Define an acid in terms of the Arrhenius theory. (2) 7.4 Give a reason why sulphuric acid is regarded as a strong acid. (1) 7.5 Bromothymol blue is used as indicator. Write down the colour change that will take place in the Erlenmeyer flask on reaching the endpoint of the titration. Choose from the following: BLUE TO YELLOW YELLOW TO BLUE GREEN TO YELLOW (1) During the titration a learner adds 25 cm3 of NaOH(aq) of concentration 0,1 mol·dm-3 to an Erlenmeyer flask and titrates this solution with H 2 SO 4 (aq) of concentration 0,1 mol·dm-3. The balanced equation for the reaction that takes place is: 2NaOH(aq) + H 2 SO 4 (aq) → Na 2 SO 4 (aq) + 2H 2 O(ℓ) 7.6 Determine the volume of H 2 SO 4 (aq) which must be added to neutralise the NaOH(aq) in the Erlenmeyer flask completely. (4) 7.7 If the learner passes the endpoint by adding 5 cm3 of the same H 2 SO 4 (aq) in excess, calculate the pH of the solution in the flask. (7) [17] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 14 DBE/2018 SCE QUESTION 8 (Start on a new page.) 8.1 Consider the electrochemical cell represented by the cell notation below, where X is an unknown metal: Pt(s) | Fe2+(aq), Fe3+(aq) || X+(aq) | X(s) The cell potential of this cell was found to be 0,03 V. 8.1.1 Write down the type of electrochemical cell illustrated above. (1) 8.1.2 What does the single line (|) in the above cell notation represent? (1) 8.1.3 Write down the half-reaction that takes place at the anode in the above cell. (2) 8.1.4 Identify X with the aid of a calculation. (5) 8.2 A Pt(s) | Fe2+(aq), Fe3+(aq) half-cell is connected to a Cu(s) | Cu2+(aq) half- cell. Write down the: 8.2.1 Chemical symbol for the electrode in the cathode half-cell (1) 8.2.2 NAME of the oxidising agent (1) 8.2.3 Overall balanced cell reaction that takes place in this cell (3) [14] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 15 DBE/2018 SCE QUESTION 9 (Start on a new page.) The diagram below shows an electrolytic cell used to electroplate an iron rod with COPPER. Solution X is made up of an unknown NITRATE. Power source Iron rod A Solution X 9.1 Solutions, such as solution X, are always used in electrochemical cells. 9.1.1 Write down the general term used to describe these solutions. (1) 9.1.2 What is the function of these solutions in electrochemical cells? (1) 9.2 Write down the FORMULA of solution X. (1) 9.3 Which electrode (A or IRON ROD) is the negative electrode? Give a reason for the answer. (2) 9.4 Write down the half-reaction that takes place at electrode A. (2) 9.5 Electrode A is now replaced by a silver rod without making any other changes to the cell. After a while, TWO metallic ions are found to be present in the solution. 9.5.1 Name the TWO metallic ions present in the solution. (2) 9.5.2 Refer to the relative strengths of oxidising agents to explain which ONE of the two ions will preferably be involved in the plating process. (2) [11] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 16 DBE/2018 SCE QUESTION 10 (Start on a new page.) The flow diagram below shows the steps used to prepare fertilisers X and Y. Labels I and II represent types of chemical reactions and P is a compound. P + H2(g) H2SO4 I Fertiliser X Ammonia NO (g) Brown gas Liquid C II Fertiliser Y 10.1 Write down the NAME of the reaction labelled: 10.1.1 I (1) 10.1.2 II (1) 10.2 Write down the NAME or FORMULA of: 10.2.1 Compound P (1) 10.2.2 The brown gas (1) 10.2.3 Liquid C (1) 10.3 Write down a balanced equation for: 10.3.1 The preparation of fertiliser X (3) 10.3.2 Reaction I (3) 10.4 Fertiliser Y is ammonium nitrate. Calculate the mass percentage of nitrogen in fertiliser Y. (3) [14] TOTAL: 150 Copyright reserved

Downloaded from hlayiso.com Physical Sciences/P2 1 DBE/2018 SCE DATA FOR PHYSICAL SCIENCES GRADE 12 PAPER 2 (CHEMISTRY) GEGEWENS VIR FISIESE WETENSKAPPE GRAAD 12 VRAESTEL 2 (CHEMIE) TABLE 1: PHYSICAL CONSTANTS/TABEL 1: FISIESE KONSTANTES NAME/NAAM SYMBOL/SIMBOOL VALUE/WAARDE Standard pressure pθ 1,013 x 105 Pa Standaarddruk Molar gas volume at STP Vm 22,4 dm3∙mol-1 Molêre gasvolume by STD Standard temperature Tθ 273 K Standaardtemperatuur Charge on electron e -1,6 x 10-19 C Lading op elektron Avogadro's constant NA 6,02 x 1023 mol-1 Avogadro-konstante TABLE 2: FORMULAE/TABEL 2: FORMULES m N n= n= M NA n m V c= or/of c= n= V MV Vm c a v a na = pH = -log[H 3 O+] c b v b nb K w = [H 3 O+][OH-] = 1 x 10-14 at/by 298 K Eθcell = Eθcathode − Eθanode / E θsel = E katode θ − E θanode or/of E θcell = E reduction θ − E θoxidation / E θsel = E reduksie θ − E θoksidasie or/of E θcell = E oxidising θ θ agent − E reducing agent / E sel = E oksideermiddel − E reduseermiddel θ θ θ Copyright reserved Please turn over

Physical Sciences/P2 Downloaded from hlayiso.com 2 DBE/2018 SCE 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) (III) (IV) (V) (VI) (VII) (VIII) Atomic number 1 KEY/SLEUTEL Atoomgetal 2 2,1 H He 1 29 4 3 4 Electronegativity Symbol 5 6 7 8 9 10 1,9 Cu 1,0 Li 1,5 Be Elektronegatiwiteit 63,5 Simbool 2,0 B 2,5 C 3,0 N 3,5 O 4,0 F Ne 7 9 11 12 14 16 19 20 11 12 13 14 15 16 17 18 0,9 Na 1,2 Mg Approximate relative atomic mass 1,5 Aℓ 1,8 Si 2,1 P 2,5 S 3,0 Cℓ Ar 23 24 Benaderde relatiewe atoommassa 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 0,8 K 1,0 Ca 1,3 Sc 1,5 Ti 1,6 V 1,6 Cr 1,5 Mn 1,8 Fe 1,8 Co 1,8 Ni 1,9 Cu 1,6 Zn 1,6 Ga 1,8 Ge 2,0 As 2,4 Se 2,8 Br Kr 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 0,8 Rb 1,0 Sr 1,2 Y 1,4 Zr Nb 1,8 Mo 1,9 Tc 2,2 Ru 2,2 Rh 2,2 Pd 1,9 Ag 1,7 Cd 1,7 In 1,8 Sn 1,9 Sb 2,1 Te 2,5 I Xe 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 0,7 Cs 0,9 Ba La 1,6 Hf Ta W Re Os Ir Pt Au Hg 1,8 Tℓ 1,8 Pb 1,9 Bi 2,0 Po 2,5 At Rn 133 137 139 179 181 184 186 190 192 195 197 201 204 207 209 87 88 89 0,7 Fr 0,9 Ra Ac 58 59 60 61 62 63 64 65 66 67 68 69 70 71 226 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

Downloaded from hlayiso.com Physical Sciences/P2 3 DBE/2018 SCE TABLE 4A: STANDARD REDUCTION POTENTIALS TABEL 4A: STANDAARD-REDUKSIEPOTENSIALE θ Half-reactions/Halfreaksies E (V) − − F 2 (g) + 2e ⇌ 2F + 2,87 3+ − 2+ Co +e ⇌ Co + 1,81 + H 2 O 2 + 2H +2e− ⇌ 2H 2 O +1,77 − + 2+ MnO 4 + 8H + 5e− ⇌ Mn + 4H 2 O + 1,51 − − Cℓ 2 (g) + 2e ⇌ 2Cℓ + 1,36 2− + 3+ Cr 2 O 7 + 14H + 6e− ⇌ 2Cr + 7H 2 O + 1,33 + − O 2 (g) + 4H + 4e ⇌ 2H 2 O + 1,23 + − 2+ MnO 2 + 4H + 2e ⇌ Mn + 2H 2 O + 1,23 2+ Pt + 2e− ⇌ Pt + 1,20 Br 2 (ℓ) + 2e− ⇌ 2Br− + 1,07 − + − NO 3 + 4H + 3e ⇌ NO(g) + 2H 2 O + 0,96 Increasing reducing ability/Toenemende reduserende vermoë 2+ − Hg + 2e ⇌ Hg(ℓ) + 0,85 + Ag + e− ⇌ Ag + 0,80 Increasing oxidising ability/Toenemende oksiderende vermoë − + − NO 3 + 2H + e ⇌ NO 2 (g) + H 2 O + 0,80 3+ − 2+ Fe +e ⇌ Fe + 0,77 + − O 2 (g) + 2H + 2e ⇌ H2O2 + 0,68 − − I 2 + 2e ⇌ 2I + 0,54 + Cu + e− ⇌ Cu + 0,52 SO 2 + 4H + 4e + − ⇌ S + 2H 2 O + 0,45 2H 2 O + O 2 + 4e− ⇌ 4OH− + 0,40 2+ − Cu + 2e ⇌ Cu + 0,34 2− + SO 4 + 4H + 2e− ⇌ SO 2 (g) + 2H 2 O + 0,17 2+ − + Cu +e ⇌ Cu + 0,16 4+ 2+ Sn + 2e− ⇌ Sn + 0,15 + − S + 2H + 2e ⇌ H 2 S(g) + 0,14 + 2H + 2e− ⇌ H 2 (g) 0,00 3+ − Fe + 3e ⇌ Fe − 0,06 2+ Pb + 2e− ⇌ Pb − 0,13 2+ − Sn + 2e ⇌ Sn − 0,14 2+ Ni + 2e− ⇌ Ni − 0,27 2+ Co + 2e− ⇌ Co − 0,28 2+ − Cd + 2e ⇌ Cd − 0,40 3+ 2+ Cr + e− ⇌ Cr − 0,41 2+ − Fe + 2e ⇌ Fe − 0,44 3+ Cr + 3e− ⇌ Cr − 0,74 2+ − Zn + 2e ⇌ Zn − 0,76 2H 2 O + 2e− ⇌ H 2 (g) + 2OH− − 0,83 2+ − Cr + 2e ⇌ Cr − 0,91 2+ Mn + 2e− ⇌ Mn − 1,18 3+ − Aℓ + 3e ⇌ Aℓ − 1,66 2+ Mg + 2e− ⇌ Mg − 2,36 + Na + e− ⇌ Na − 2,71 2+ − Ca + 2e ⇌ Ca − 2,87 2+ Sr + 2e− ⇌ Sr − 2,89 2+ − Ba + 2e ⇌ Ba − 2,90 + - Cs + e ⇌ Cs - 2,92 + − K +e ⇌ K − 2,93 + Li + e− ⇌ Li − 3,05 Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 4 DBE/2018 SCE TABLE 4B: STANDARD REDUCTION POTENTIALS TABEL 4B: STANDAARD-REDUKSIEPOTENSIALE θ Half-reactions/Halfreaksies E (V) + − Li + e ⇌ Li − 3,05 + K + e− ⇌ K − 2,93 + − Cs + e ⇌ Cs − 2,92 2+ Ba + 2e− ⇌ Ba − 2,90 2+ − Sr + 2e ⇌ Sr − 2,89 2+ Ca + 2e− ⇌ Ca − 2,87 + Na + e− ⇌ Na − 2,71 2+ − Mg + 2e ⇌ Mg − 2,36 3+ Aℓ + 3e− ⇌ Aℓ − 1,66 2+ − Mn + 2e ⇌ Mn − 1,18 2+ Cr + 2e− ⇌ Cr − 0,91 Increasing oxidising ability/Toenemende oksiderende vermoë − − 2H 2 O + 2e ⇌ H 2 (g) + 2OH − 0,83 2+ Zn + 2e− ⇌ Zn − 0,76 Increasing reducing ability/Toenemende reduserende vermoë 3+ − Cr + 3e ⇌ Cr − 0,74 2+ Fe + 2e− ⇌ Fe − 0,44 3+ − 2+ Cr +e ⇌ Cr − 0,41 2+ Cd + 2e− ⇌ Cd − 0,40 2+ Co + 2e− ⇌ Co − 0,28 2+ − Ni + 2e ⇌ Ni − 0,27 2+ Sn + 2e− ⇌ Sn − 0,14 2+ − Pb + 2e ⇌ Pb − 0,13 3+ Fe + 3e− ⇌ Fe − 0,06 + − 2H + 2e ⇌ H 2 (g) 0,00 + S + 2H + 2e− ⇌ H 2 S(g) + 0,14 4+ − 2+ Sn + 2e ⇌ Sn + 0,15 2+ + Cu + e− ⇌ Cu + 0,16 2− + SO 4 + 4H + 2e− ⇌ SO 2 (g) + 2H 2 O + 0,17 2+ − Cu + 2e ⇌ Cu + 0,34 − − 2H 2 O + O 2 + 4e ⇌ 4OH + 0,40 + SO 2 + 4H + 4e− ⇌ S + 2H 2 O + 0,45 + − Cu + e ⇌ Cu + 0,52 − − I 2 + 2e ⇌ 2I + 0,54 + O 2 (g) + 2H + 2e− ⇌ H2O2 + 0,68 3+ − 2+ Fe +e ⇌ Fe + 0,77 − + − NO 3 + 2H + e ⇌ NO 2 (g) + H 2 O + 0,80 + − Ag + e ⇌ Ag + 0,80 2+ Hg + 2e− ⇌ Hg(ℓ) + 0,85 − + − NO 3 + 4H + 3e ⇌ NO(g) + 2H 2 O + 0,96 − − Br 2 (ℓ) + 2e ⇌ 2Br + 1,07 2+ − Pt +2e ⇌ Pt + 1,20 + 2+ MnO 2 + 4H + 2e− ⇌ Mn + 2H 2 O + 1,23 + O 2 (g) + 4H + 4e− ⇌ 2H 2 O + 1,23 2− + 3+ Cr 2 O 7 + 14H + 6e− ⇌ 2Cr + 7H 2 O + 1,33 − − Cℓ 2 (g) + 2e ⇌ 2Cℓ + 1,36 − + 2+ MnO 4 + 8H + 5e− ⇌ Mn + 4H 2 O + 1,51 + H 2 O 2 + 2H +2 e− ⇌ 2H 2 O +1,77 3+ − 2+ Co +e ⇌ Co + 1,81 F 2 (g) + 2e− ⇌ 2F− + 2,87 Copyright reserved