Physical Sciences Grade 12 P2 Eastern Cape June 2023 QP

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 JUNE 2023 PHYSICAL SCIENCES: (CHEMISTRY) P2 MARKS: 150 TIME: 3 hours This question paper consists of 21 pages, including 4 data sheets.

Downloaded from hlayiso.com 2 PHYSICAL SCIENCES P2 (EC/JUNE 2023) INSTRUCTIONS AND INFORMATION 1. Write your name and surname in the appropriate space on the ANSWER BOOK. 2. This question paper consists of SEVEN 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 sub-questions, 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 (EC/JUNE 2023) 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 correct letter (A–D) next to the question numbers (1.1–1.10) in the ANSWER BOOK, for example 1.11 E. 1.1 Which ONE of the following homologous series has members that are SATURATED hydrocarbons? A Alcohols B Alkenes C Alkanes D Alkynes (2) 1.2 When an ALKENE is converted to an ALKANE, the catalyst that is used is … A Ni or Fe. B Pt or Ni. C H2SO4 or Ni. D H2SO4 or Pt. (2) 1.3 The boiling point versus chain length graph below was obtained for straight chain molecules of aldehydes, alkanes, alcohols and carboxylic acids. The curve for EACH homologous series is labelled as A, B, C or D. A B Boiling point (K) C D Chain length Which ONE of the curves above represents alcohols? A Curve A B Curve B C Curve C D Curve D (2) Copyright reserved Please turn over

Downloaded from hlayiso.com 4 PHYSICAL SCIENCES P2 (EC/JUNE 2023) 1.4 Consider the organic reaction below: CH2CH2 + X Alcohol Which ONE of the following is CORRECT about reactant X and the reaction condition? X is … Reaction condition A H2O Concentrated H2SO4 in excess B H2O Small quantity of concentrated H2SO4 C dilute KOH Mild heat D concentrated KOH Strong heat (2) 1.5 Consider the reaction between an EXCESS hydrochloric acid (HCℓ) solution and magnesium powder: Mg (s) + 2 HCℓ (aq) MgCl2 (aq) + H2 (g) Which ONE of the following factors when INCREASED will cause an increase in both the REACTION RATE and the TOTAL VOLUME of H 2 produced? A Mass of Mg B Volume of HCℓ C Concentration of HCℓ D Temperature of the reaction mixture (2) 1.6 Which ONE of the following will affect BOTH the equilibrium position of a reversible reaction, and its Kc value? A Mass B Pressure C Temperature D Concentration (2) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 5 1.7 The graph below shows how the reaction rate changes with time for the reaction represented by the balanced equation below: 2 HI(g) ⇌ H2(g) + I2(g) ΔH > 0 Reaction Rate t1 Time (s) Consider the following changes made to the equilibrium mixture. I More HI is added II Temperature is increased III Pressure is increased by decreasing the volume at constant temperature Which ONE of the following changes will cause the change at t1? A I only B II only C I and III D III only (2) 1.8 A substance that loses protons in some reactions and gains protons in other reactions is called a/an … A base. B acid. C ampholyte. D acid-base indicator. (2) Copyright reserved Please turn over

Downloaded from hlayiso.com 6 PHYSICAL SCIENCES P2 (EC/JUNE 2023) 1.9 Four titrations are carried out using the pairs of substances shown below. For which pair of substances when titrated will phenolphthalein be the most suitable indicator? A HNO3 and NaOH B CH3COOH and NaOH C Na2CO3 and HCℓ D H2SO4 and NaOH (2) 1.10 The following equilibrium exists in pure water at 25 °C. 2 H2O(ℓ) ⇌ H3O+(aq) + OH-(aq) How will the addition of NaOH to the pure water affect the concentration of the hydronium ion [ H3O+] and pH of water at constant temperature? [ H3O+] pH of water A Increases Decreases B Decreases Increases C Increases Increases D Decreases Decreases (2) [20] Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 7 QUESTION 2 (Start on a new page.) Consider the organic compounds A to F given in the table below. A C5H12 B CH3 CH2CH3 CH2CH2 C C CH3 CH3 C Propan-1-ol D Methanal E CH3CH(OH)CH3 F CH3CH2CH2COOH G Propanone H H C C H 2.1 Write down the LETTER that represents the following compounds: 2.1.1 An alkyne (1) 2.1.2 An aldehyde (1) 2.1.3 That has the general formula CnH2n+2 (1) 2.1.4 That has a solution with pH < 7 (1) 2.1.5 That has the same general formula as an ester (1) 2.2 Compounds C and E are structural isomers. 2.2.1 Define the term structural isomer. (2) 2.2.2 What TYPE of structural isomers are compounds C and E? Choose from CHAIN, POSITIONAL or FUNCTIONAL. (1) 2.2.3 Is compound E a PRIMARY, SECONDARY or TERTIARY ALCOHOL? Give a reason for your answer. (3) Copyright reserved Please turn over

Downloaded from hlayiso.com 8 PHYSICAL SCIENCES P2 (EC/JUNE 2023) 2.3 Write down the: 2.3.1 IUPAC name of compound B (3) 2.3.2 CONDENSED STRUCTURAL formula of a FUNCTIONAL isomer of compound G (2) 2.4 For compound F write down the: 2.4.1 Empirical formula (1) 2.4.2 Name of its functional group (1) 2.5 Compound F reacts with methanol in the presence of concentrated sulphuric acid to produce organic product X. For compound X write down the: 2.5.1 Name of the homologous series to which it belongs (1) 2.5.2 IUPAC name and STRUCTURAL formula (4) [23] Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 9 QUESTION 3 (Start on a new page.) The table below shows a number of organic compounds and their respective melting points. Study the table below and answer the questions that follow. Compound Melting point (°C) A Propane -187 B Butane -138 C Pentane -129 D 2-methyl butane X E Butanal -96,8 F Butan-1-ol -89,8 3.1 Define the term melting point. (2) 3.2 Explain the trend in melting points from compound A to C. (3) 3.3 Which compound (A, B or C) will have the highest vapour pressure at a given temperature? Give a reason for the answer by referring to the data in the table above. (2) 3.4 Consider compounds C and D. The melting point of compound D is indicated by X. 3.4.1 Draw the structural formula of compound D. (2) 3.4.2 How does the value of X compare to the melting point of compound C? Choose from GREATER THAN -129 °C or LESS THAN -129 °C. (1) 3.4.3 Is the comparison between compounds C and D a fair comparison? Write only YES or NO. Give a reason for your answer. (2) 3.5 Explain the difference in the melting points of compounds E and F by referring to intermolecular forces present and energy. (4) [16] Copyright reserved Please turn over

Downloaded from hlayiso.com 10 PHYSICAL SCIENCES P2 (EC/JUNE 2023) QUESTION 4 (Start on a new page.) 4.1 Consider the flow diagram showing organic reactions given below. Reaction 1 CH3CH(Br)CH3 C3H8O hydrolysis A A C4 C4Reaction 2 Br2 ALKENE Compound Q Reaction 3 Consider REACTION 1. C4 C4 Write down: 4.1.1 The name of the homologous series to which the compound C3H8O belongs (1) 4.1.2 ONE reaction condition (1) 4.1.3 The formula of the inorganic reactant (1) Consider REACTION 2. 4.1.4 Name the type of elimination reaction taking place. (1) 4.1.5 Using structural formulae for the organic compounds, write down a balanced equation for the reaction. (6) Consider REACTIONS 3 and 4. Write down the: 4.1.6 Name given to these types of reactions (1) 4.1.7 Formula of the inorganic reactant used in REACTION 4 (1) 4.1.8 IUPAC name and structural formula of compound Q (4) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 11 4.2 Consider the incomplete equations for reactions I and II. I C15H32 ALKANE P + 2 Q + CxH6 II CH3CH2Br + KOH Q + KBr + Z In reaction I, the compound C15H32 undergoes cracking. Q is an organic compound while compound Z is an inorganic compound. The compounds Q and CxH6 have the same FUNCTIONAL GROUP. 4.2.1 Define cracking. (2) 4.2.2 Write down a balanced equation for the complete combustion of ALKANE P. (Show ALL workings.) (6) [24] Copyright reserved Please turn over

Downloaded from hlayiso.com 12 PHYSICAL SCIENCES P2 (EC/JUNE 2023) QUESTION 5 (Start on a new page.) A group of learners use the reaction between sodium thiosulphate (Na 2S2O3) and EXCESS hydrochloric acid (HCℓ) to investigate one of the factors that affect reaction rate. The balanced equation for the reaction is: Na2S2O3 (aq) + 2 HCℓ (aq) 2 NaCℓ (aq) + S (s) + H2O (ℓ) + SO2 (g) The learners carry out five experiments under the same conditions changing only the factor that is investigated in EACH experiment using the experimental set-up shown below. Na2S2O3 solution with HCℓ White paper They recorded the time taken for the cross to become invisible, when viewed from the top. The learners’ results are shown in the graph below. GRAPH OF 1/TIME VERSUS INITIAL CONCENTRATION OF Na2S2O3 0,06 1/time (s-1) 0,04 0,02 0,05 0,1 0,15 0,20 Initial Concentration of Na2S2O3 (mol·dm-3) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 13 5.1 Define reaction rate. (2) 5.2 Write down an investigative question for the above investigation. (2) 5.3 Name the substance responsible for the disappearance of the cross. (1) 5.4 Give a reason why the same cross must be used in ALL the experiments. (1) 5.5 Use the collision theory to explain the effect of concentration on reaction rate. (3) 5.6 In one of the experiments 50 cm3 of Na2S2O3 is used and it takes 20 seconds for the cross to become invisible. Calculate the total mass of sulphur, S, formed in this experiment. (6) 5.7 The graph below represents Maxwell-Boltzmann distribution curve for SO2(g) at 30 °C. Q Kinetic energy Q is a label on the vertical axis. 5.7.1 What does Q in the graph represent? (1) Redraw the graph in the ANSWER BOOK. Clearly label the curve as A. 5.7.2 On the same set of axes, sketch the curve that will be obtained for SO2(g) at 40 °C. Label this curve as B. (2) [18] Copyright reserved Please turn over

Downloaded from hlayiso.com 14 PHYSICAL SCIENCES P2 (EC/JUNE 2023) QUESTION 6 (Start on a new page.) The following reaction reaches equilibrium at a temperature of 200 °C. PCℓ 5(g) ⇌ PCℓ 3(g) + Cℓ2 (g) ∆H > 0 6.1 State Le Chatelier’s principle. (2) 6.2 Two conditions must be met for a chemical reaction to establish equilibrium. One of the conditions is represented by the double arrow “⇌”. State the other condition. (1) 6.3 The reaction is initiated by heating 83,4 grams PCℓ5(g) in a sealed 2 dm3 container. At equilibrium it is found that the initial concentration of PCℓ 5 has changed by x mol·dm-3. 6.3.1 Show that the equilibrium constant is, Kc = x2/ 0,2 – x. (6) 6.3.2 The concentration of PCℓ5 at equilibrium is found to be 0,001 mol·dm-3. Show by calculation that the value of Kc is equal to 39,601 at 200 °C. (2) 6.3.3 Is there a LOW or HIGH YIELD at 200 °C? Give a reason for your answer. (2) 6.4 What effect will the addition of a suitable catalyst have on the following: Choose from DECREASES, INCREASES or NO EFFECT. 6.4.1 Percentage decomposition of PCℓ5 (g)? (1) 6.4.2 Time taken to reach equilibrium? (1) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 15 6.5 The graph below shows changes of concentration of reagents PCℓ5 and Cℓ2 against time. PCℓ5 Concentration (mol·dm-3) Cℓ2 0 t1 t2 t3 t4 Time (min) 6.5.1 What does the horizontal section of the graph between 0–t1 represent? (1) At time t2 the temperature of the equilibrium mixture is changed. 6.5.2 Was the container COOLED or HEATED at time t2? (1) 6.5.3 Use Le Chatelier’s principle to fully explain the answer to QUESTION 6.5.2. (3) [20] Copyright reserved Please turn over

Downloaded from hlayiso.com 16 PHYSICAL SCIENCES P2 (EC/JUNE 2023) QUESTION 7 (Start on a new page.) 7.1 An investigation is carried out to compare the strengths of TWO acids CH3COOH(aq) and H2CO3(aq). To determine the strength of EACH acid electrical conductivity of the acid is measured at 25 °C using the experimental set-up shown below. The concentration of the acids is the same. A Carbon electrodes Acid 7.1.1 Define an acid according to the Arrhenius theory. (2) 7.1.2 State ONE property of the carbon electrodes that make them suitable for this investigation. (1) The ammeter readings taken for each acid are given in the table below. FORMULA OF ACID AMMETER READING (mA) CH3COOH 500 H2CO3 133 7.1.3 Which ACID (CH3COOH or H2CO3) is stronger? Explain the answer. (3) H2CO3 undergoes ionisation in a TWO step process as shown below: I H2CO3 + H2O ⇌ HCO3̄ + H3O+ II HCO3̄ + H2O ⇌ X + H3O+ Write down the formula of the substance(s) that: 7.1.4 Are bases in reaction I (2) 7.1.5 Is represented by X in reaction II (1) Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 17 7.2 Ammonium chloride (NH4Cℓ) undergoes hydrolysis. 7.2.1 Define hydrolysis. (2) 7.2.2 Is a solution of ammonium chloride ACIDIC, ALKALINE or NEUTRAL? Explain the answer with the aid of a balanced equation. (4) 7.3 A school laboratory has a hydrochloric acid (HCℓ) solution of concentration 1 mol·dm-3. 7.3.1 Calculate the pH of the HCℓ solution. (3) 250 cm3 of the HCℓ solution is used to dissolve an eggshell. 7.3.2 Calculate the number of moles of HCℓ in 250 cm3 of solution (3) The eggshell contains 99,3% calcium carbonate (CaCO3) by mass. The calcium carbonate (CaCO3) in the eggshell reacts with EXCESS HCℓ according to the balanced equation below: CaCO3 (s) + 2 HCℓ (aq) CaCℓ2 (aq) + H2O (ℓ) + CO2 (g) The unreacted HCℓ is neutralised by 103 cm3 of a solution of sodium hydroxide (NaOH) of concentration 0,5 mol·dm-3 according to the balanced equation: NaOH (aq) + HCℓ (aq) NaCℓ (aq) + H2O (ℓ) 7.3.3 Calculate the mass of the eggshell. (8) [29] TOTAL: 150 Copyright reserved Please turn over

Downloaded from hlayiso.com 18 PHYSICAL SCIENCES P2 (EC/JUNE 2023) NATIONAL SENIOR CERTIFICATE NASIONALE SENIOR SERTIFIKAAT 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 Standaarddruk p 1,013 x 105 Pa Molar gas volume at STP Molêre gasvolume teen STD Vm 22,4 dm3∙mol-1 Standard temperature Standaardtemperatuur Tθ 273 K Charge on electron Lading op elektron e -1,6 x 10-19 C Avogadro’s constant NA 6,02 x 1023 mol-1 Avogadro se konstante TABLE 2: FORMULAE/TABEL 2: FORMULES m n m n= M or/of c = V or/of c = MV pH= -log[H3O+] N ca Va na Kw = [H3O+][OH-] = 1x10-14 n= N or/of = A cb Vb nb at/by 298 K V n= V o Copyright reserved Please turn over

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 19 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 1 Atomic number 2 2,1 H He 1 29 4 3 4 Elektronegatiwiteit Simbool 5 6 7 8 9 10 1,0 Li 1,5 Be 1,9 2,0 B 2,5 C 3,0 N 3,5 O 4,0 F Ne Electronegativity Cu Symbol 7 9 11 12 14 16 19 20 11 12 63,5 13 14 15 16 17 18 0,9 Na 1,2 Mg 1,5 Aℓ 1,8 Si 2,1 P 2,5 S 3,0 Cℓ Ar Benaderde relatiewe atoommassa 23 24 27 28 31 32 35,5 40 19 20 21 22 23 24 25 26 relative Approximate 27 atomic 28 mass29 30 31 32 33 34 35 36 0,8 K 1,0 Ca 1,3 Sc 1,5Ti 1,6 V 1,6 Cr 1,5Mn Fe1,8 Co Ni1,8 Cu 1,8 1,9 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 1,4Zr Nb 1,8 Mo 1,9Tc Ru2,2 Rh Pd2,2 Ag 2,2 1,9 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 1,6Hf 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 226 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

Downloaded from hlayiso.com 20 PHYSICAL SCIENCES P2 (EC/JUNE 2023) TABLE 4A: STANDARD REDUCTION POTENTIALS TABEL 4A: STANDAARD REDUKSIEPOTENSIALE Half-reactions/Halfreaksies E θ (V) F2(g) + 2e− ⇌ 2F− + 2,87 Co 3+ +e − ⇌ Co2+ + 1,81 H2O2 + 2H+ +2e− ⇌ 2H2O +1,77 − MnO 4 + 8H+ + 5e− ⇌ Mn2+ + 4H2O + 1,51 Cℓ2(g) + 2e− ⇌ 2Cℓ − + 1,36 2− Cr2O 7 + 14H+ + 6e− ⇌ 2Cr 3+ + 7H2O + 1,33 O2(g) + 4H+ + 4e− ⇌ 2H2O + 1,23 MnO2 + 4H + 2e + − ⇌ Mn 2+ + 2H2O + 1,23 Pt2+ + 2e− ⇌ Pt + 1,20 Br2(ℓ) + 2e− ⇌ 2Br− + 1,07 − NO 3 + 4H+ + 3e− ⇌ Increasing reducing ability/Toenemende reduserende vermoë NO(g) + 2H2O + 0,96 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 Fe3+ + e− ⇌ Fe 2+ + 0,77 O2(g) + 2H + 2e + − ⇌ H2O2 + 0,68 I2 + 2e − ⇌ 2I − + 0,54 Cu+ + e− ⇌ Cu + 0,52 SO2 + 4H+ + 4e− ⇌ S + 2H2O + 0,45 2H2O + O2 + 4e − ⇌ 4OH − + 0,40 Cu2+ + 2e− ⇌ Cu + 0,34 2− SO 4 + 4H+ + 2e− ⇌ SO2(g) + 2H2O + 0,17 Cu2+ + e− ⇌ Cu+ + 0,16 Sn 4+ + 2e − ⇌ Sn 2+ + 0,15 S + 2H+ + 2e− ⇌ H2S(g) + 0,14 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 Co 2+ + 2e − ⇌ Co − 0,28 Cd2+ + 2e− ⇌ Cd − 0,40 Cr3+ + e− ⇌ Cr2+ − 0,41 Fe2+ + 2e− ⇌ Fe − 0,44 Cr 3+ + 3e − ⇌ Cr − 0,74 Zn2+ + 2e− ⇌ Zn − 0,76 2H2O + 2e− ⇌ H2(g) + 2OH− − 0,83 Cr2+ + 2e− ⇌ Cr − 0,91 Mn 2+ + 2e − ⇌ Mn − 1,18 Aℓ3+ + 3e− ⇌ Aℓ − 1,66 Mg2+ + 2e− ⇌ Mg − 2,36 Na+ + e− ⇌ Na − 2,71 Ca 2+ + 2e − ⇌ Ca − 2,87 Sr2+ + 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

Downloaded from hlayiso.com (EC/JUNE 2023) PHYSICAL SCIENCES P2 21 TABLE 4B: STANDARD REDUCTION POTENTIALS TABEL 4B: STANDAARD REDUKSIEPOTENSIALE Half-reactions/Halfreaksies E θ (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 Aℓ3+ + 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 2+ Fe + 2e − ⇌ Fe − 0,44 Cr3+ + e− ⇌ Cr2+ − 0,41 Cd2+ + 2e− ⇌ Cd − 0,40 Co2+ + 2e− ⇌ Co − 0,28 Ni2+ + 2e− ⇌ Ni − 0,27 2+ Sn + 2e − ⇌ Sn − 0,14 Pb2+ + 2e− ⇌ Pb − 0,13 Fe3+ + 3e− ⇌ Fe − 0,06 2H+ + 2e− ⇌ H2(g) 0,00 S + 2H+ + 2e− ⇌ H2S(g) + 0,14 4+ Sn + 2e − ⇌ Sn 2+ + 0,15 Cu2+ + 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 Hg2+ + 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− ⇌ 3+ 2Cr + 7H2O + 1,33 Cℓ2(g) + 2e− ⇌ 2Cℓ − + 1,36 − MnO 4 + 8H+ + 5e− ⇌ Mn2+ + 4H2O + 1,51 H2O2 + 2H+ +2 e− ⇌ 2H2O +1,77 3+ Co + e − ⇌ Co2+ + 1,81 F2(g) + 2e− ⇌ 2F− + 2,87 Copyright reserved Please turn over