Physical Sciences Grade 12 P2 NSC November 2013 QP (Eng)

Downloaded from hlayiso.com NATIONAL SENIOR CERTIFICATE GRADE 12 PHYSICAL SCIENCES: CHEMISTRY (P2) NOVEMBER 2013 MARKS: 150 TIME: 3 hours This question paper consists of 15 pages and 4 data sheets. Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 2 DBE/November 2013 NSC INSTRUCTIONS AND INFORMATION 1. Write your centre number and examination number in the appropriate spaces on the ANSWER BOOK. 2. Answer ALL the questions in the ANSWER BOOK. 3. This question paper consists of TWO sections: SECTION A (25) SECTION B (125) 4. You may use a non-programmable calculator. 5. You may use appropriate mathematical instruments. 6. Number the answers correctly according to the numbering system used in this question paper. 7. Data sheets and a periodic table are attached for your use. 8. Give brief motivations, discussions, et cetera where required. 9. Round off your final numerical answers to a minimum of TWO decimal places. Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 3 DBE/November 2013 NSC SECTION A QUESTION 1: ONE-WORD ITEMS Give ONE word/term for each of the following descriptions. Write only the word/term next to the question number (1.1–1.5) in the ANSWER BOOK. 1.1 The industrial preparation of nitrogen gas from liquid air (1) 1.2 The removal of water from a compound during a reaction (1) 1.3 A theory used to explain how factors, such as temperature, change the rate of a reaction (1) 1.4 The general term used to describe a substance that donates electrons to another substance (1) 1.5 The general term used to describe a class of organic compounds in which one member differs from the previous one by a CH 2 group (1) [5] QUESTION 2: MULTIPLE-CHOICE QUESTIONS 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 (2.1–2.10) in the ANSWER BOOK. 2.1 Which ONE of the following is the functional group of aldehydes? A ─ COO ─ B ─ COOH C ─ CHO D ─ OH (2) 2.2 Which ONE of the following hydrocarbons always gives a product with the same IUPAC name when ANY ONE of its hydrogen atoms is replaced with a chlorine atom? A Hexane B Hex-1-ene C Cyclohexane D Cyclohexene (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 4 DBE/November 2013 NSC 2.3 The equation below represents the reaction that takes place when an organic compound and concentrated sodium hydroxide are strongly heated. X represents the major organic product formed. H H H H C C C H + NaOH X + NaBr + H2O H Br H Which ONE of the following is the correct IUPAC name for compound X? A Prop-1-ene B Prop-2-ene C Propan-1-ol D Propan-2-ol (2) 2.4 The graphs below represent the molecular distribution for a reaction at different temperatures. Number of molecules P Q R S Kinetic energy Which ONE of the graphs above represents the reaction at the highest temperature? A P B Q C R D S (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 5 DBE/November 2013 NSC 2.5 The reaction represented below reaches equilibrium in a closed container. CuO(s) + H 2 (g) ⇌ Cu(s) + H 2 O(g) ∆H < 0 Which ONE of the following changes will increase the yield of products? A Increase temperature. B Decrease temperature. C Increase pressure by decreasing the volume. D Decrease pressure by increasing the volume. (2) 2.6 The graph below represents the decomposition of N 2 O 4 (g) in a closed container according to the following equation: N 2 O 4 (g) ⇌ 2NO 2 (g) Concentration (mol∙dm-3) [N2O4] [NO2] t1 Time (s) Which ONE of the following correctly describes the situation at t 1 ? A The N 2 O 4 gas is used up. B The NO 2 gas is used up. C The rate of the forward reaction equals the rate of the reverse reaction. D The concentrations of the reactant and the product are equal. (2) 2.7 Which ONE of the following is the strongest oxidising agent? A F 2 (g) B F-(aq) C Li(s) D Li+(aq) (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 6 DBE/November 2013 NSC 2.8 Which ONE of the following statements about a galvanic cell in operation is CORRECT? A ∆H for the cell reaction is positive. B The overall cell reaction is non-spontaneous. C The emf is negative. D ∆H for the cell reaction is negative. (2) 2.9 The function of the salt bridge in a galvanic cell in operation is to ... A allow anions to travel to the cathode. B maintain electrical neutrality in the half-cells. C allow electrons to flow through it. D provide ions to react at the anode and cathode. (2) 2.10 The major product formed at the ANODE in a membrane cell is ... A hydrogen. B oxygen. C chlorine. D hydroxide ions. (2) [20] TOTAL SECTION A: 25 Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 7 DBE/November 2013 NSC SECTION B INSTRUCTIONS 1. Start EACH question on a NEW page. 2. Leave ONE line between two subquestions, for example between QUESTION 3.1 and QUESTION 3.2. 3. Show the formulae and substitutions in ALL calculations. 4. Round off your final numerical answers to a minimum of TWO decimal places. QUESTION 3 (Start on a new page.) The letters A to F in the table below represent six organic compounds. H H C H H H H H H O H H A H B H C C C C H C C C C C C H H H H H H H H H C H H C CH 3 CH ═ CHCH 2 CH 2 CH 3 D Pentyl propanoate H H Br Br H H H H C H H C C C C C C H H H E H H H H H F H C C C C C H H C H H H H H C H H 3.1 Write down the letter(s) that represent(s) the following: 3.1.1 Alkenes (2) 3.1.2 A ketone (1) 3.1.3 A compound with the general formula C n H 2n-2 (1) 3.1.4 A structural isomer of cyclohexene (2) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 8 DBE/November 2013 NSC 3.2 Write down the IUPAC name of compound: 3.2.1 A (2) 3.2.2 E (2) 3.2.3 F (2) 3.3 Compound D is prepared by reacting two organic compounds in the presence of an acid as catalyst. Write down the: 3.3.1 Homologous series to which compound D belongs (1) 3.3.2 Structural formula of compound D (2) 3.3.3 IUPAC name of the organic acid used to prepare compound D (1) 3.3.4 NAME or FORMULA of the catalyst used (1) [17] QUESTION 4 (Start on a new page.) A laboratory technician is supplied with three unlabelled bottles containing an alcohol, an aldehyde and an alkane respectively of comparable molecular mass. She takes a sample from each bottle and labels them P, Q and R. In order to identify each sample, she determines the boiling point of each under the same conditions. The results are shown in the table below. BOILING POINT SAMPLE (°C) P 76 Q 36 R 118 4.1 For this investigation, write down the: 4.1.1 Independent variable (1) 4.1.2 Dependent variable (1) 4.2 From the passage above, write down a phrase that shows that this investigation is a fair test. (1) Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 9 DBE/November 2013 NSC 4.3 Which sample (P, Q or R) is the: 4.3.1 Alkane (1) 4.3.2 Alcohol (1) 4.3.3 Refer to boiling point and the type of intermolecular forces present between alcohol molecules to give a reason for the answer in QUESTION 4.3.2. (2) 4.4 The alkane is identified as pentane. Will the boiling point of hexane be HIGHER THAN or LOWER THAN that of pentane? Refer to MOLECULAR STRUCTURE, INTERMOLECULAR FORCES and ENERGY needed to explain the answer. (4) [11] QUESTION 5 (Start on a new page.) Two straight chain compounds, P and Q, each have the following molecular formula: P: C 4 H 10 Q: C 4 H 8 5.1 Write down the name of the homologous series to which Q belongs. (1) 5.2 Compound P reacts with chlorine to form 2-chlorobutane. Write down: 5.2.1 A balanced chemical equation, using MOLECULAR FORMULAE, for the reaction that takes place (3) 5.2.2 The type of reaction that takes place (1) 5.2.3 One reaction condition (other than the solvent needed) (1) 5.3 Compound Q takes part in reactions as shown in the flow diagram below. Compound Q (C4H8) Bromine Reaction 1 2,3-dibromobutane Compound P (C4H10) Write down the: 5.3.1 Structural formula for 2,3-dibromobutane (2) 5.3.2 IUPAC name of compound Q (2) 5.3.3 Balanced equation, using structural formulae, for reaction 1 (4) 5.3.4 Type of reaction that occurs in reaction 1 (1) [15] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 10 DBE/November 2013 NSC QUESTION 6 (Start on a new page.) A hydrogen peroxide solution dissociates slowly at room temperature according to the following equation: 2H 2 O 2 (aq) → 2H 2 O(ℓ) + O 2 (g) During an investigation, learners compare the effectiveness of three different catalysts on the rate of decomposition of hydrogen peroxide. They place EQUAL AMOUNTS of sufficient hydrogen peroxide into three separate containers. They then add EQUAL AMOUNTS of the three catalysts, P, Q and R, to the hydrogen peroxide in the three containers respectively and measure the rate at which oxygen gas is produced. 6.1 For this investigation, write down the: 6.1.1 Independent variable (1) 6.1.2 Dependent variable (1) The results obtained are shown in the graph below. Volume of oxygen (cm3) R P Q Time (s) 6.2 Which catalyst is the most effective? Give a reason for the answer. (2) 6.3 Fully explain, by referring to the collision theory, how a catalyst increases the rate of a reaction. (3) In another experiment, the learners obtain the following results for the decomposition of hydrogen peroxide: TIME (s) H 2 O 2 CONCENTRATION (mol∙dm-3) 0 0,0200 200 0,0160 400 0,0131 600 0,0106 800 0,0086 6.4 Calculate the AVERAGE rate of decomposition (in mol∙dm-3·s-1) of H 2 O 2 (aq) in the first 400 s. (3) 6.5 Will the rate of decomposition at 600 s be GREATER THAN, LESS THAN or EQUAL TO the rate calculated in QUESTION 6.4? Give a reason for the answer. (2) 6.6 Calculate the mass of oxygen produced in the first 600 s if 50 cm3 of hydrogen peroxide decomposes in this time interval. (5) [17] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 11 DBE/November 2013 NSC QUESTION 7 (Start on a new page.) A chemical engineer studies the reaction of nitrogen and oxygen in a laboratory. The reaction reaches equilibrium in a closed container at a certain temperature, T, according to the following balanced equation: N 2 (g) + O 2 (g) ⇌ 2NO(g) Initially, 2 mol of nitrogen and 2 mol of oxygen are mixed in a 5 dm3 sealed container. The equilibrium constant (K C ) for the reaction at this temperature is 1,2 x 10-4. 7.1 Is the yield of NO(g) at temperature T HIGH or LOW? Give a reason for the answer. (2) 7.2 Calculate the equilibrium concentration of NO(g) at this temperature. (8) 7.3 How will each of the following changes affect the YIELD of NO(g)? Write down only INCREASES, DECREASES or REMAINS THE SAME. 7.3.1 The volume of the reaction vessel is decreased at constant temperature. (1) 7.3.2 An inert gas such as argon is added to the mixture. (1) 7.4 It is found that K C of the reaction increases with an increase in temperature. Is this reaction exothermic or endothermic? Explain the answer. (3) [15] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 12 DBE/November 2013 NSC QUESTION 8 (Start on a new page.) The diagram below shows a galvanic cell operating under standard conditions. The cell reaction taking place when the cell is functioning is: 6Cℓ - (aq) + 2Au3+(aq) → 3Cℓ 2 (g) + 2Au(s) V S Cℓ2(g) Au Pt Cℓ-(aq) Au3+(aq) With switch S OPEN, the initial reading on the voltmeter is 0,14 V. 8.1 Write down the: 8.1.1 NAME or FORMULA of the oxidising agent (1) 8.1.2 Half-reaction which takes place at the anode (2) 8.1.3 Cell notation for this cell (3) 8.2 Calculate the standard reduction potential of Au. (4) Switch S is now closed and the bulb lights up. 8.3 How will the reading on the voltmeter now compare to the INITIAL reading of 0,14 V? Write down only LARGER THAN, SMALLER THAN or EQUAL TO. Give a reason for the answer. (2) [12] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 13 DBE/November 2013 NSC QUESTION 9 (Start on a new page.) The diagram below represents a simplified electrolytic cell used to electroplate a spanner with chromium. The spanner is continuously rotated during the process of electroplating. DC power supply Electrode X Spanner Cr(NO3)3(aq) A constant current passes through the solution and the concentration of Cr(NO 3 ) 3 (aq) remains constant during the process. In the process, a total of 0,03 moles of electrons is transferred in the electrolytic cell. 9.1 Define the term electrolysis. (2) 9.2 Write down the: 9.2.1 Half-reaction that occurs at the spanner (2) 9.2.2 NAME or FORMULA of the metal of which electrode X is made (1) 9.2.3 NAME or FORMULA of the oxidising agent (1) 9.3 Calculate the gain in mass of the spanner. (4) [10] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 14 DBE/November 2013 NSC QUESTION 10 (Start on a new page.) Lead-acid batteries consist of several cells. A sulphuric acid solution is used as electrolyte in these batteries. 10.1 Define the term electrolyte. (2) The standard reduction potentials for the half-reactions that take place in a cell of a lead-acid battery are as follows: PbO 2 (s) + SO 4 2-(aq) + 4H+(aq) + 2e- ⇌ PbSO 4 (s) + 2H 2 O(ℓ) Eθ = +1,69 V PbSO 4 (s) + 2e- ⇌ Pb(s) + SO 4 2-(aq) Eθ = - 0,36 V 10.2 Write down the half-reaction that takes place at the anode of this cell. (2) 10.3 Write down the overall cell reaction when the cell delivers current. (3) 10.4 A number of the cells above are connected in series to form a 300 V battery which operates at standard conditions. Calculate the: 10.4.1 Maximum energy stored in the battery if its capacity is 7 500 A∙h (5) 10.4.2 Minimum number of cells in this battery (5) [17] Copyright reserved Please turn over

Downloaded from hlayiso.com Physical Sciences/P2 15 DBE/November 2013 NSC QUESTION 11 (Start on a new page.) 11.1 A farmer wants to produce the following fruit and vegetables for the market: spinach; potatoes; apples Write down the NAME of the most important primary nutrient required to enhance: 11.1.1 Root growth of potato plants (1) 11.1.2 Leaf growth of spinach (1) 11.1.3 Flower and fruit production of apple trees (1) 11.2 Ammonia must be produced in large quantities to produce nitrogen-based fertilisers. 11.2.1 Write down the name of the process used in the industrial preparation of ammonia. (1) 11.2.2 Write down a balanced chemical equation for the reaction that takes place in the process named in QUESTION 11.2.1. (3) 11.3 Ammonium hydrogen phosphate, (NH 4 ) 2 HPO 4 , is a type of fertiliser used in agriculture. Refer to the type of elements of which this fertiliser is composed to give a reason why it will be advantageous for a farmer to use this fertiliser instead of a fertiliser such as ammonium nitrate, NH 4 NO 3 . (2) 11.4 Describe ONE negative impact on humans when fertiliser runs off into dams and rivers as a result of rain. (2) [11] TOTAL SECTION B: 125 GRAND TOTAL: 150 Copyright reserved

Downloaded from hlayiso.com Physical Sciences/P2 1 DBE/November 2013 NSC 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 TABLE 2: FORMULAE/TABEL 2: FORMULES n c= V m n= or/of M m c= MV Ecell = Eθcathode − Eθanode / E θsel = E katode θ θ − E θanode or/of q = I∆t E θcell = E reduction θ − E θoxidation / E θsel = E reduksie θ − E θoksidasie W = Vq or/of E θcell = E oxidising θ θ θ θ θ agent − E reducing agent / E sel = E oksideermiddel − E reduseermiddel Copyright reserved Please turn over

Physical Sciences/P2 Downloaded from hlayiso.com 2 DBE/November 2013 NSC 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/November 2013 NSC 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 Increasing oxidising ability/Toenemende oksiderende vermoë − + 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 − + 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/November 2013 NSC 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 Increasing oxidising ability/Toenemende oksiderende vermoë 2+ − Mn + 2e ⇌ Mn − 1,18 2+ Cr + 2e− ⇌ Cr − 0,91 Increasing reducing ability/Toenemende reduserende vermoë 2H 2 O + 2e− ⇌ H 2 (g) + 2OH− − 0,83 2+ − Zn + 2e ⇌ Zn − 0,76 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 + 2 e− ⇌ 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