Physical Sciences Grade 12 P2 Western Cape Mock 2014 QP

Downloaded from hlayiso.com Physical Sciences/P2 1 CWED September 2014 NSC CAPE WINELANDS EDUCATION DISTRICT PHYSICAL SCIENCES P2 CHEMISTRY SEPTEMBER 2014 MARKS: 150 TIME: 3 hours This exam paper consists of 14 pages and four data sheets.

Downloaded from hlayiso.com INSTRUCTIONS AND INFORMATION 1. Write your NAME on the ANSWER FOLIOS. 2. Answer ALL the questions on the ANSWER FOLIOS. 3. You may use a non-programmable calculator. 4. You may use appropriate mathematical instruments. 5. Start each main question on a new page. 6. Number the answers correctly according to the numbering system used in this question paper. 7. YOU ARE ADVISED TO USE THE ATTACHED DATA SHEETS. 8. Give brief motivations, discussions, et cetera, where required. 9. Round off calculations to two decimal places. QUESTION 1: MULTIPLE CHOICE Four options are provided as possible answers to the following questions. Each question has only ONE correct answer. Write only the letter (A – D) next to the question number (1.1 – 1.10) on one page of your ANSWER FOLIO’S. 1.1 The correct IUPAC name of the following compound is: CH3 | CH3—CH2—CH—CH—CH3 | Cl A 3-chloro-4-methylpentane B 3-chloro-2-methylpentane C 2-methyl-3-chloropentane D 4-methyl-3-chloropentane. (2) 1.2 Which one of the following statements is INCORRECT? A Sunflower oil undergoes a substitution reaction to form margarine B Alkynes are more reactive than alkenes C Aldehydes and ketones contain a carbonyl group D Propyl ethanoate can be made from propanoic acid and ethanol. (2) 2

Downloaded from hlayiso.com 1.3 Consider graph A and B below. Graph A shows the distribution of molecular energies. X represents the minimum kinetic energy required for a reaction. Graph A number of molecules kinetic energy X Graph B shows the potential energy curve for the same reaction is represented below. Which of the following will be the correct value for X shown in graph A? Ep B C D A course of reaction A 10 kJ B 103 kJ C 93 kJ D 35 kJ (2) 3

Downloaded from hlayiso.com 1.4 The reaction represented by the balanced equation below reaches equilibrium in a closed container. H2(g) + I2(g) ⇌ 2HI(g) ∆H < 0 How will the equilibrium be affected if, first the volume of the container is decreased and then the temperature is increased? A At first no effect and then the reverse reaction is favoured. B The reverse reaction is favoured by both changes. C At first no effect and then the forward reaction is favoured D A first the reverse reaction is favoured and then the forward reaction is favoured. (2) 1.5 Consider the reversible reaction: N2(g) + 3 H2(g) ⇄ 2 NH3 (g) ∆H < 0. The graph of reaction rate vs time for the above reaction is shown below. The solid line reflects the forward reaction, while the broken line depicts the reverse reaction. Which one of the changes below explains the change in the graph at time X? A Temperature is decreased B Temperature is increased C Concentration of H2 is decreased D Concentration of N2 is increased. (2) 1.6 Consider the ionisation reaction: NH3 + H2O ⇄ NH4+ + OH- A conjugate acid-base pair is… A NH3 ; NH4+ B NH3 ; H2O C H2O ; NH4+ D NH3 ; OH- (2) 4

Downloaded from hlayiso.com 1.7 A 1 mol.dm-3 solution of each of a number of acids is prepared. Which solution will have the lowest pH? A HCl B H2SO4 C CH3COOH (2) D NH4OH. 1.8 Which ONE of the following reactions is spontaneous under standard conditions? A Sn4+ SO2 + 2H2O → Sn2+ + SO42- + 4H+ B I2 + 2Br- → 2I- + Br2 C 2 H2O → O2 + 2H2 D 2Ag+ + Fe2+ → 2Ag + Fe3+. (2) 1.9 In the chlor-alkali membrane cell, brine is pumped into the cell. Which ONE of the following correctly indicates the products formed at the respective electrodes? Positive electrode Negative electrode A Cl2 (g) Na (s) B OH- (aq) Na (s) C O2 (g) H2 (g) D Cl2 (g) H2 (g) (2) 1.10 Which fertilizer will best address the following needs of a crop? Increase tolerance Assist with ripening to disease of fruit A K2SO4 H2NCONH2 B KCl Ca3(H2PO4)2 C Ca3(H2PO4)2 KCl D NH4NO3 Ca3(H2PO4)2 (2) [20] 5

Downloaded from hlayiso.com QUESTION 2 The table below shows the vapour pressures of various organic compounds at 25 OC. Molar mass Vapour Pressure Compound (g•mol-1) (x102 Pa) pentane 72 573,0 hexane 86 160,0 heptane 100 48,0 propan-1-ol 60 21,0 propan-2-ol 60 44,0 butan-1-ol 74 6,2 butan-2-ol 74 18,3 pentan-1-ol 88 2,2 pentan-2-ol 88 8,04 ethanoic acid 60 15,3 propanone 58 240,0 2.1 Write down 2.1.1 the general formula of the homologous series of which heptane is a member. (1) 2.1.2 the IUPAC name and structural formula of an isomer of pentane. (2) 2.1.3 the structural formula of propanone. (2) 2.2 State and explain the relationship between vapour pressure and the strength of intermolecular forces. (3) 2.3 Explain the difference in vapour pressure between pentane, hexane and heptane. Refer to strength of intermolecular forces in your answer. (2) 2.4 Explain why: 2.4.1 The vapour pressure of butan-1-ol is so much lower than that of pentane. (2) 2.4.2 The vapour pressure of secondary alcohols are higher than the primary alcohols that has the same structural formula. (2) 2.5 Which compound will have the higher boiling point: ethanoic acid or propan-1-ol? (1) 2.6 Refer to vapour pressure, intermolecular forces and energy and give a reason for your answer to 2.5. (3) [18] 6

Downloaded from hlayiso.com QUESTION 3 Bromine water can be used to distinguish between saturated and unsaturated compounds. Equal amounts of hex-2-ene and hexane are added to respective test tubes A and B at room temperature; 2cm3 of bromine water is added to each and the test tubes shaken. The solution in test tube A becomes clearer, while the solution in test tube B has a brownish colour. 3.1 What is meant by an unsaturated compound? (2) 3.2 Using structural formulas, write down the equation for the reaction in test tube A. (3) 3.3 Name the reaction condition required for a reaction to take place in test tube B . (1) 3.4 Consider the flow diagram below: CH2═CHCH2CH3 2. hydration reaction 1 X 3. substitution elimination 2-bromobutane Y(main product) 4. elimination 3.4.1 Name the type of reaction in reaction 1. (1) 3.4.2 State the reaction condition required for reaction 2, which is the hydration reaction that forms compound X. (1) 3.4.3 State the reaction conditions for reaction 3, that is the substitution reaction where X forms from 2-bromobutane. (2) 3.4.4 Draw the structural formula of Y and give its IUPAC name. (2) 3.5 The diagram below shows the structural formula for polyethylene. 3.5.1 Write down the IUPAC name of the monomer that formed polyethylene. (1) 3.5.2 State the type of polymerization that occurs when polyethylene is formed from its monomer. (1) [14] 7

Downloaded from hlayiso.com QUESTION 4 You are asked to do an investigation into how the concentration of reactants affects reaction rate. The reaction used for the investigation is that between sodium thiosulfate, Na2S2O3, and hydrochloric acid (HCℓ). When combined, a substance is produced which causes the solution to become cloudy: Na2S2O3(aq) + 2HCl(aq) → 2NaCl(aq) + S(s) + H2O(l) + SO2(g) List of chemicals: 250 ml of sodium thiosulfate solution; distilled water; hydrochloric acid solution of concentration 2 mol·dm-3 Method: (incomplete) 1. Use a black pen to draw a large cross on a piece of paper 2. Put 50 ml of sodium thiosulfate solution into a conical flask. 3. Add 5 ml of hydrochloric acid, starting the stopwatch; swirl the mixture once or twice. 4. Place the reaction flask on the paper with the cross and note the time when the cross can no longer be seen. 5. Repeat the experiment but …. 6. Repeat the experiment a third time but … 7. Record the results in a table. Results: Experiment 1 2 3 Time taken (s) 3,0 4,5 6,9 4.1 Give the definition of reaction rate. (1) 4.2 For the experiment described above, name the 4.2.1 independent variable (1) 4.2.2 dependant variable (1) 8

Downloaded from hlayiso.com 4.3 Consider the method: 4.3.1 Rewrite points 5 and 6 describing what you would change each time so that the aim of the experiment can be achieved. (Note how the Time taken changes- do not be concerned with how much it changes). (3) 4.3.2 What needs to be done in order to ensure that this is a fair test? (1) 4.4 Write down the name or formula of the substance responsible for the cloudiness. (1) 4.5 Consider the table of results: which experiment (1, 2 or 3) occurred at the highest reaction rate? (1) [9] QUESTION 5 The following equation represents a reaction in equilibrium 2CrO42- (aq) + 2H+ (aq) ⇄ Cr2O72- (aq) + H2O (l) yellow orange 5.1 Define chemical equilibrium. (2) 5.2 Is this an example of an open or closed system? (1) 5.3 A few drops of nitric acid (HNO3) is added to the mixture. 5.3.1 What will the colour of the solution be? Write only ORANGE or YELLOW. (1) 5.3.2 Give a reason for this observation. (2) 5.4 Write down the expression of the equilibrium constant (Kc) for this reaction. (2) 5.5 Will the addition of water have any influence on the value of the equilibrium constant . (1) 5.6 What colour will the solution be after a few pellets of sodium hydroxide (NaOH) is added to the solution? Write only ORANGE or YELLOW. (1) 5.7 Use Le Chatelier’s Principle and explain the answer to Question 5.6. (3) [13] 9

Downloaded from hlayiso.com QUESTION 6 Consider the equilibrium in a saturated solution of sodium chloride as shown by the equation below: NaCl(s) ⇄ Na+(aq) + Cl-(aq) 6.1 Is the forward reaction exothermic or endothermic? (1) 6.2 At 25OC, the solubility of sodium chloride is 35,9g per 100cm3 water. Calculate the equilibrium constant for the system. (6) 6.3 What change to the reaction conditions will increase the value of Kc for this reaction? Give an explanation for the answer. (4) 6.4 At the same temperature, the equilibrium constant of a saturated solution of silver chloride (AgCl) is 1,8x10-10. Is silver chloride more soluble or less soluble than sodium chloride at 25 OC? (1) [12] QUESTION 7 You are tasked to determine the percentage ethanoic acid (CH3COOH) in vinegar. 7,5g of commercial vinegar is dissolved in 100cm3 water . 25cm3 of this solution is neutralised by 28,5cm3 of a sodium hydroxide (NaOH) solution of concentration 0,11mol•dm-3. The balanced equation for the reaction is NaOH (aq) + CH3COOH (aq) → CH3COONa + H2O 7.1 Calculate the pH of the sodium hydroxide solution. (5) 7.2 Calculate the number of moles sodium hydroxide used to neutralise the 25cm3 of acid. (2) 7.3 Calculate the percentage ethanoic acid in the vinegar. (5) [12] 10

Downloaded from hlayiso.com QUESTION 8 The industrial preparation of sulphuric acid (H2SO4) can be represented as follows: I II III IV S SO2 SO3 X H2SO4 8.1 Give the name of the industrial process used to prepare sulphuric acid. (1) 8.2 Give the name or formula of compound X. (1) 8.3 Give the name or formula of the catalyst used. (1) 8.4 Sulphuric acid is a strong acid. Define strong acid. (1) 8.5 Write an equation to illustrate how sulphuric acid ionises in water. (3) 8.6 Identify the conjugate acid in the equation in Question 8.5. (1) 8.7 Give the term used for the conjugate base in QUESTION 8.5 that is able to act as both a proton donor or a proton acceptor. (1) 8.8 Give the term used for an acid such as H2SO4 that are able to donate two hydrogen ions per formula unit. (1) 8.9 Consider the following reaction of sulphuric acid: 2H2SO4 + Cu → CuSO4 + 2H2O + SO2 (g) The half reactions for this reaction is given as Cu
Cu2+ + 2e- SO4-2 + 4H+ + 2e-
2H2O + SO2 8.9.1 Is sulphuric acid acting as an oxidising agent or reducing agent? (1) 8.9.2 Explain the answer in QUESTION 8.9.1 by referring to the oxidising reaction and electron transfer. (2) [13] 11

Downloaded from hlayiso.com QUESTION 9 Consider the cell below which operates under standard conditions: V Fe Mg FeCl3(aq) MgSO MgCl24 (aq) (aq) KCl The nett cell reaction for this cell is 2 Fe3+ + 3 Mg (s) → 2 Fe (s) + 3 Mg2+ 9.1 What energy conversion takes place in this cell? (1) 9.2 State the standard conditions that will apply to this cell. (2) 9.3 Which electrode is the ANODE: Fe or Mg? (1) 9.4 Write down the oxidation half reaction for this cell. (3) 9.5 After the cell had been operating a while, it is determined that the mass of the magnesium plate changed by 0,96g. Calculate the change in mass of the iron electrode over the same period of time. (5) 9.6 A light bulb is marked “2 V”. Calculate the emf of the cell and state whether or not the light bulb will burn if used in this circuit. Ignore internal resistance. (5) 9.7 How will the concentration of Mg2+-ions change while the cell is in operation? (1) 9.8 What effect, if any, will this change in Question 9.7 have on the voltmeter reading over a period of time? Give a reason for your answer. (2) [20] 12

Downloaded from hlayiso.com QUESTION 10 Pure aluminium oxide (Al2O3) is produced by the purification of ore that is mixed with molten cryolite. The aluminium oxide is used to produce Alumminium as shown in the diagram below. Alluminium is formed at the carbon lining. power supply graphite electrode carbon lining molten cryolite molten aluminium The net equation for this reaction is 3+ 2- 4Al (l) + 6O (l) → 4Al(s) + 3O (g) 2 10.1 Name the ore in which aluminium oxide occurs. (1) 10.2 Consider the diagram: is this an electrolytic or galvanic cell? (1) 10.3 Are the carbon lining indicated in the diagram the anode or the cathode?. (1) 10.4 Must the carbon lining be connected to the positive or negative terminal of the power supply? (1) 10.5 Write down the half-reaction that occurs at the anode. (2) 10.6 Must the power supply be alternating current ( AC) or direct current (DC)? Give a reason for your answer. . (2) [8] 13

Downloaded from hlayiso.com QUESTION 11 Ammonium nitrate is one of the inorganic fertilizers manufactured industrially. This flow-diagram illustrates the process. NH3 X NO2 HNO3 Y NH3 is produced industrially according to the following equation: N2 (g) + 3H2 (g) ⇄ 2NH3 (g) ∆H < 0. According to Le Chatelier’s Principle, ideal conditions for a maximum yield are a low temperature and a high pressure. 11.1 Name the process by which NH3 is formed. (1) 11.2 The temperature at which process occurs is about 450 OC, which is relatively high. Give a reason why lower temperatures are NOT used. (1) 11.3 Identify compound X. (1) 11.4 Write down the balanced equation for the reaction in which NH3 is turned into compound X . (2) 11.5 Write down the formula of the fertilizer Y. (1) 11.6 Scientists are concerned about pollution of the underground water by nitrate fertilizers. Give one reason why this pollution is dangerous for humans. (1) 11.7 A gardener finds an old 50kg bag of fertilizer. The label on the bag is partially worn (see diagram below). She has the contents analysed and It is determined that the percentage nitrogen in the bag is 18,75%. 5:2:_ (30) 50 kg Determine the missing component in the N:P:K ratio. (4) [11] TOTAL: 150 14

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE (CAPS) NASIONALE SENIOR SERTIFIKAAT (KABV) 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 Standaardtemperatuur Tθ 273 K Charge on electron e -1,6 x 10-19 C TABLE 2: FORMULAE/TABEL 2: FORMULES Δm Δt m N n= n= M NA c= n m V OR c = n= V MV V m c V n a a= a c V n b b b Kw = [H3O+][OH-] = 1 x 10-14 at 298 K Eθcell = Eθcathode − E θanode E θsel = E katode θ − E θanode E θcell = E reduction θ − E θoxidation E θsel = E reduksie θ − E θoksidasie E θcell = E θoxidising agent − E reducing θ agent E θsel = E θoksideermi ddel − E reduseermi θ ddel 15

Downloaded from hlayiso.com Physical Sciences/P2 16 CWED September 2014 NSC TABLE/TABEL 3: THE PERIODIC TABLE OF ELEMENTS/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 1,0 Li 1,5 Be Elektronegatiwiteit 1,9 Cu Simbool 2,0 B 2,5 C 3,0 N 3,5 O 4,0 F Ne 7 9 63,5 11 12 14 16 19 20 11 12 Approximate relative atomic mass 13 14 15 16 17 18 0,9 Na 1,2 Mg Benaderde relatiewe atoommassa 1,5 Aℓ 1,8 Si 2,1 P 2,5 S 3,0 Cℓ Ar 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 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 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

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Downloaded from hlayiso.com Physical Sciences/P2 18 CWED September 2014 NSC TABLE 4A: STANDARD REDUCTION POTENTIALS/ TABEL 4A: STANDAARD REDUKSIEPOTENSIALE Half-reactions/Halfreaksies E θ (V) F2(g) + 2e− ⇌ 2F− + 2,87 3+ − 2+ Co +e ⇌ Co + 1,82 − + − 2+ MnO 4 + 8H + 5e ⇌ Mn + 4H2O + 1,52 − − Cℓ2(g) + 2e ⇌ 2Cℓ + 1,36 2− + 3+ Cr2O 7 + 14H + 6e− ⇌ 2Cr + 7H2O + 1,33 + − 2+ MnO2 + 4H + 2e ⇌ Mn + 2H2O + 1,28 + − O2(g) + 4H + 3e ⇌ 2H2O + 1,23 Br2(ℓ) + 2e− ⇌ 2Br− + 1,06 − + − NO 3 + 4H + 3e ⇌ NO(g) + 2H2O + 0,96 + − Ag + e Ag + 0,80 Increasing reducing ability/Toenemende reduserende vermoë ⇌ 2+ − Hg + 2e Hg(ℓ) + 0,78 Increasing oxidising ability/Toenemende oksiderende vermoë ⇌ − + − NO 3 + 2H + e ⇌ NO2(g) + H2O + 0,78 3+ − 2+ Fe +e ⇌ Fe + 0,77 + O2(g) + 2H + 2e− ⇌ H2O2 + 0,68 − − I2 + 2e ⇌ 2I + 0,54 + Cu + e− ⇌ Cu + 0,52 + SO2 + 4H + 2e− ⇌ S + 2H2O + 0,45 2H2O + O2 + 4e− ⇌ 4OH− + 0,40 2+ − Cu + 2e ⇌ Cu + 0,34 2− + SO 4 + 4H + 4e− ⇌ SO2(g) + 2H2O + 0,17 2+ − + Cu +e ⇌ Cu + 0,16 4+ 2+ Sn + 2e− ⇌ Sn + 0,15 + S + 2H + 2e− ⇌ H2S(g) + 0,14 + − 2H + 2e ⇌ H2(g) 0,00 3+ Fe + 3e− ⇌ Fe − 0,04 2+ Pb + 2e− ⇌ Pb − 0,13 2+ Sn + 2e− ⇌ Sn − 0,14 2+ − Ni + 2e ⇌ Ni − 0,25 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+ − Cr + 2e ⇌ Cr − 0,74 2+ Zn + 2e− ⇌ Zn − 0,76 2H2O + 2e− ⇌ H2(g) + 2OH− − 0,83 2+ − Mn + 2e ⇌ Mn − 1,18 3+ Aℓ + 3e− ⇌ Aℓ − 1,66 2+ − Mg + 2e ⇌ Mg − 2,37 + Na + e− ⇌ Na − 2,71 2+ − Ca + 2e ⇌ Ca − 2,87 2+ Ba + 2e− ⇌ Ba − 2,90 + − K +e ⇌ K − 2,92 + Li + e− ⇌ Li − 3,04

Downloaded from hlayiso.com TABLE 4B: STANDARD REDUCTION POTENTIALS/ TABEL 4B: STANDAARD REDUKSIEPOTENSIALE Half-reactions/Halfreaksies E θ (V) + Li + e− ⇌ Li − 3,04 + K + e− ⇌ K − 2,92 2+ − Ba + 2e ⇌ Ba − 2,90 2+ Ca + 2e− ⇌ Ca − 2,87 + − Na + e ⇌ Na − 2,71 2+ Mg + 2e− ⇌ Mg − 2,37 3+ − Aℓ + 3e ⇌ Aℓ − 1,66 2+ Mn + 2e− ⇌ Mn − 1,18 − − 2H2O + 2e ⇌ H2(g) + 2OH − 0,83 2+ Zn + 2e− ⇌ Zn − 0,76 2+ Cr + 2e− ⇌ Cr − 0,74 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 − 0,25 Increasing oxidising ability/Toenemende oksiderende vermoë Increasing reducing ability/Toenemende reduserende vermoë 2+ − Sn + 2e ⇌ Sn − 0,14 2+ Pb + 2e− ⇌ Pb − 0,13 3+ − Fe + 3e ⇌ Fe − 0,04 + 2H + 2e− ⇌ H2(g) 0,00 + − S + 2H + 2e ⇌ H2S(g) + 0,14 4+ 2+ Sn + 2e− ⇌ Sn + 0,15 2+ − + Cu +e ⇌ Cu + 0,16 2− + SO 4 + 4H + 4e− ⇌ SO2(g) + 2H2O + 0,17 2+ − Cu + 2e ⇌ Cu + 0,34 − − 2H2O + O2 + 4e ⇌ 4OH + 0,40 + SO2 + 4H + 2e− ⇌ S + 2H2O + 0,45 + Cu + e− ⇌ Cu + 0,52 I2 + 2e− ⇌ 2I− + 0,54 + O2(g) + 2H + 2e− ⇌ H2O2 + 0,68 3+ 2+ Fe + e− ⇌ Fe + 0,77 − + − NO 3 + 2H + e ⇌ NO2(g) + H2O + 0,78 2+ − Hg + 2e ⇌ Hg(ℓ) + 0,78 + − Ag + e ⇌ Ag + 0,80 − + − NO 3 + 4H + 3e ⇌ NO(g) + 2H2O + 0,96 − − Br2(ℓ) + 2e ⇌ 2Br + 1,06 + O2(g) + 4H + 3e− ⇌ 2H2O + 1,23 + 2+ MnO2 + 4H + 2e− ⇌ Mn + 2H2O + 1,28 2− + 3+ Cr2O 7 + 14H + 6e− ⇌ 2Cr + 7H2O + 1,33 − − Cℓ2(g) + 2e ⇌ 2Cℓ + 1,36 − + − 2+ MnO 4 + 8H + 5e ⇌ Mn + 4H2O + 1,52 3+ − 2+ Co +e ⇌ Co + 1,82 F2(g) + 2e− ⇌ 2F− + 2,87 19