Physical Sciences/P2
1
NSC
CWED September 2014
CAPE WINELANDS EDUCATION DISTRICT
PHYSICAL SCIENCES P2
CHEMISTRY
SEPTEMBER 2014
MARKS: 150
TIME: 3 hours
This
his exam paper consists of 14 pages and four data sheets.
INSTRUCTIONS AND INFORMATION
1.
2.
3.
4.
5.
6.
7.
8.
9.
Write your NAME on the ANSWER FOLIOS.
Answer ALL the questions on the ANSWER FOLIOS.
You may use a non-programmable calculator.
You may use appropriate mathematical instruments.
Start each main question on a new page.
Number the answers correctly according to the numbering system used in
this question paper.
YOU ARE ADVISED TO USE THE ATTACHED DATA SHEETS.
Give brief motivations, discussions, et cetera, where required.
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
(2)
D 4-methyl-3-chloropentane.
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)
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
1.3
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
A
10 kJ
B
103 kJ
C
93 kJ
D
35 kJ
course of reaction
(2)
3
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.
1.5
(2)
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
B
C
D
1.6
Temperature is decreased
Temperature is increased
Concentration of H2 is decreased
Concentration of N2 is increased.
(2)
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
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+.
1.9
(2)
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
to disease
Assist with ripening
of fruit
A
K2SO4
H2NCONH2
B
KCl
Ca3(H2PO4)2
C
Ca3(H2PO4)2
KCl
D
NH4NO3
Ca3(H2PO4)2
(2)
[20]
5
QUESTION 2
The table below shows the vapour pressures of various organic compounds at 25 OC.
Molar mass
(g•mol-1)
Vapour Pressure
(x102 Pa)
pentane
hexane
heptane
72
86
100
573,0
160,0
48,0
propan-1-ol
propan-2-ol
butan-1-ol
butan-2-ol
pentan-1-ol
pentan-2-ol
60
60
74
74
88
88
21,0
44,0
6,2
18,3
2,2
8,04
ethanoic acid
propanone
60
58
15,3
240,0
Compound
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.
2.4
Explain why:
2.4.1 The vapour pressure of butan-1-ol is so much lower than that of
pentane.
2.5
2.6
(2)
(2)
2.4.2 The vapour pressure of secondary alcohols are higher than the primary
alcohols that has the same structural formula.
(2)
Which compound will have the higher boiling point: ethanoic acid or
propan-1-ol?
(1)
Refer to vapour pressure, intermolecular forces and energy and give a
reason for your answer to 2.5.
(3)
[18]
6
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.
shaken
The solution in test tube A becomes clearer,
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)
Name the reaction condition required for a reaction to take place in test
tube B .
(1)
3.3
3.4
Consider the flow diagram below:
below
CH2═CHCH2CH3
2. hydration
reaction 1
X
3. substitution
elimination
2-bromobutane
4. elimination
Y(main product)
3.4.1 Name the type of reaction in reaction
r
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,
3, that is the substitution
reaction where X forms from 2-bromobutane.
2
(2)
3.4.4 Draw the structural formula of Y and give its IUPAC name.
3.5
(2)
The diagram below shows the structural formula for polyethylene.
3.5.1 Write down the IUPAC name of the monomer
monomer that formed
polyethylene.
3.5.2 State the type of polymerization that occurs when polyethylene
is formed from its monomer.
7
(1)
(1)
[14]
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
4.3
4.4
4.5
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)
Write down the name or formula of the substance responsible for
the cloudiness.
(1)
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.
5.4
5.5
5.6
5.7
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)
Write down the expression of the equilibrium constant (Kc) for this
reaction.
(2)
Will the addition of water have any influence on the value of the
equilibrium constant .
(1)
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)
Use Le Chatelier’s Principle and explain the answer to Question 5.6.
(3)
[13]
9
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
QUESTION 8
The industrial preparation of sulphuric acid (H2SO4) can be represented as follows:
I
S
II
SO2
IV
III
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+ + 2eSO4-2 + 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
QUESTION 9
Consider the cell below which operates under standard conditions:
V
Fe
Mg
MgSO
(aq)
MgCl24 (aq)
FeCl3(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
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+
24Al (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
QUESTION 11
Ammonium nitrate is one of the inorganic fertilizers manufactured industrially.
This flow-diagram illustrates the process.
X
NH3
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.
14
(4)
[11]
TOTAL: 150
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
Standard pressure
Standaarddruk
Molar gas volume at STP
Molêre gasvolume by STD
Standard temperature
Standaardtemperatuur
Charge on electron
SYMBOL/SIMBOOL
pθ
1,013 x 105 Pa
Vm
22,4 dm3·mol-1
Tθ
273 K
e
-1,6 x 10-19 C
TABLE 2: FORMULAE/TABEL 2: FORMULES
n=
m
M
c= n
V
VALUE/WAARDE
Δm
Δt
N
NA
V
n=
V
m
n=
OR c =
m
MV
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
θ
E θsel = E katode
− E θanode
θ
E θcell = E reduction
− E θoxidation
θ
E θsel = E reduksie
− E θoksidasie
θ
E θcell = E θoxidising agent − E reducing
agent
θ
E θsel = E θoksideermi ddel − E reduseermi
ddel
15
Physical Sciences/P2
CWED September 2014
16
NSC
TABLE/TABEL 3: THE PERIODIC TABLE OF ELEMENTS/PERIODIEKE TABEL VAN ELEMENTE
58
Ce
140
90
Th
232
4,0
3,0
2,8
2,5
8
O
16
16
S
32
34
Se
79
52
Te
128
84
Po
17
(VII)
2,5
3,5
3,0
2,1
2,5
2,4
2,1
30
Zn
65
48
Cd
112
80
Hg
201
2,0
1,5
1,6
29
Cu
63,5
47
Ag
108
79
Au
197
1,7
1,9
28
Ni
59
46
Pd
106
78
Pt
195
1,9
1,8
27
Co
59
45
Rh
103
77
Ir
192
2,2
1,8
2,2
26
Fe
56
44
Ru
101
76
Os
190
7
N
14
15
P
31
33
As
75
51
Sb
122
83
Bi
209
16
(VI)
2,0
75
Re
186
1,8
25
Mn
55
43
Tc
2,2
1,5
24
Cr
52
42
Mo
96
74
W
184
1,9
1,6
23
V
51
41
Nb
92
73
Ta
181
1,8
22
Ti
48
40
Zr
91
72
Hf
179
1,6
1,5
1,4
21
Sc
45
39
Y
89
57
La
139
89
Ac
1,6
1,3
Approximate relative atomic mass
Benaderde relatiewe atoommassa
6
C
12
14
Si
28
32
Ge
73
50
Sn
119
82
Pb
207
1,9
63,5
5
B
11
13
Aℓ
27
31
Ga
70
49
In
115
81
Tℓ
204
15
(V)
1,9
1,9
2,0
Symbol
Simbool
Cu
14
(IV)
2,5
29
13
(III)
1,8
12
1,8
11
1,8
10
1,8
9
Atomic number
Atoomgetal
Electronegativity
Elektronegatiwiteit
1,2
1,5
1,2
1,0
1,0
4
Be
9
12
Mg
24
20
Ca
40
38
Sr
88
56
Ba
137
88
Ra
226
8
7
1,6
6
1,7
5
4
1,8
3
KEY/SLEUTEL
0,9
1
H
1
3
Li
7
11
Na
23
19
K
39
37
Rb
86
55
Cs
133
87
Fr
2
(II)
0,9
0,7
0,7
0,8
0,8
0,9
1,0
2,1
1
(I)
9
F
19
17
Cℓ
35,5
35
Br
80
53
I
127
85
At
18
(VIII)
2
He
4
10
Ne
20
18
Ar
40
36
Kr
84
54
Xe
131
86
Rn
59
Pr
141
60
Nd
144
61
Pm
62
Sm
150
63
Eu
152
64
Gd
157
65
Tb
159
66
Dy
163
67
Ho
165
68
Er
167
69
Tm
169
70
Yb
173
71
Lu
175
91
Pa
92
U
238
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr
17
Physical Sciences/P2
CWED September 2014
18
NSC
TABLE 4A: STANDARD REDUCTION POTENTIALS/
TABEL 4A: STANDAARD REDUKSIEPOTENSIALE
Half-reactions/Halfreaksies
Co
3+
+e
−
MnO 4
−
+
+ 8H + 5e
Cℓ2(g) + 2e
2−
Cr2O 7
−
+ 14H + 6e
+
−
+
−
O2(g) + 4H + 3e
Br2(ℓ) + 2e−
+
NO 3 + 4H + 3e−
Increasing oxidising ability/Toenemende oksiderende vermoë
Ag + e
Hg
2+
Fe
−
+ 2e
−
NO 3
3+
−
+
+ 2H + e
+e
−
−
+
O2(g) + 2H + 2e−
I2 + 2e
−
+
Cu + e−
+
SO2 + 4H + 2e−
2H2O + O2 + 4e−
Cu
2+
+ 2e−
2−
SO 4
+ 4H + 4e
2+
+e
4+
+ 2e−
Cu
Sn
+
−
+
S + 2H + 2e−
+
−
⇌
Co
⇌
MnO2 + 4H + 2e
+
2F−
⇌
−
+
−
⇌
−
−
⇌
+ 2,87
2+
Mn
2+
+ 1,82
+ 4H2O
−
+ 1,36
2Cℓ
2Cr
3+
2+
+ 1,52
+ 7H2O
+ 1,33
+ 2H2O
+ 1,28
⇌
Mn
⇌
2H2O
+ 1,23
⇌
2Br−
+ 1,06
⇌
NO(g) + 2H2O
+ 0,96
⇌
Ag
+ 0,80
⇌
Hg(ℓ)
+ 0,78
⇌
NO2(g) + H2O
+ 0,78
2+
⇌
Fe
⇌
H2O2
+ 0,77
+ 0,68
⇌
2I
−
+ 0,54
+ 0,52
⇌
Cu
⇌
S + 2H2O
+ 0,45
⇌
4OH−
+ 0,40
⇌
Cu
+ 0,34
⇌
SO2(g) + 2H2O
+ 0,17
+
+ 0,16
⇌
Cu
⇌
Sn
2+
+ 0,15
⇌
H2S(g)
+ 0,14
⇌
H2(g)
3+
+ 3e−
⇌
Fe
− 0,04
Pb
2+
+ 2e−
⇌
Pb
− 0,13
Sn
2+
+ 2e−
⇌
Sn
− 0,14
⇌
Ni
− 0,25
⇌
Co
− 0,28
⇌
Cd
− 0,40
⇌
Cr
⇌
Fe
− 0,44
⇌
Cr
− 0,74
⇌
Cr
− 0,74
⇌
Zn
− 0,76
⇌
H2(g) + 2OH−
− 0,83
2H + 2e
Fe
Ni
2+
+ 2e
−
Co
2+
+ 2e−
Cd
2+
−
Cr
3+
+ 2e
+ e−
2+
+ 2e
Cr
3+
+ 3e−
Cr
2+
+ 2e
−
2+
+ 2e−
Fe
Zn
−
2H2O + 2e−
Mn
2+
3+
Aℓ
Mg
+ 2e
−
+ 3e−
2+
+ 2e−
+
Na + e−
2+
+ 2e−
2+
+ 2e−
Ca
Ba
+
K +e
+
−
Li + e−
2+
0,00
− 0,41
⇌
Mn
− 1,18
⇌
Aℓ
− 1,66
⇌
Mg
− 2,37
⇌
Na
− 2,71
⇌
Ca
− 2,87
⇌
Ba
− 2,90
⇌
K
− 2,92
⇌
Li
− 3,04
Increasing reducing ability/Toenemende reduserende vermoë
F2(g) + 2e−
E θ (V)
TABLE 4B: STANDARD REDUCTION POTENTIALS/
TABEL 4B: STANDAARD REDUKSIEPOTENSIALE
Half-reactions/Halfreaksies
+
K + e−
Ba
2+
+ 2e−
2+
+ 2e−
Ca
+
Na + e−
Mg
2+
3+
+ 3e−
Li
− 3,04
⇌
K
− 2,92
⇌
Ba
− 2,90
⇌
Ca
− 2,87
⇌
Na
− 2,71
⇌
Mg
− 2,37
⇌
Aℓ
− 1,66
+ 2e−
⇌
Mn
− 1,18
2H2O + 2e−
⇌
H2(g) + 2OH−
− 0,83
⇌
Zn
− 0,76
− 0,74
− 0,74
Aℓ
Mn
2+
2+
+ 2e
Cr
2+
+ 2e−
⇌
Cr
Cr
3+
+ 3e−
⇌
Cr
2+
+ 2e−
⇌
Fe
Zn
Fe
Cr
Increasing oxidising ability/Toenemende oksiderende vermoë
+ 2e−
⇌
3+
+e
−
−
Cd
2+
+ 2e−
Co
2+
−
Ni
2+
+ 2e
+ 2e−
Sn
2+
+ 2e−
Pb
2+
+ 2e−
3+
−
Fe
+ 3e
+
2H + 2e−
+
S + 2H + 2e
Sn
4+
Cu
2+
+ 2e−
+e
2−
SO 4
Cu
2+
−
−
+
+ 4H + 4e
+ 2e
−
−
2H2O + O2 + 4e
−
+
SO2 + 4H + 2e−
+
Cu + e−
I2 + 2e−
+
O2(g) + 2H + 2e−
Fe
3+
−
NO 3
Hg
2+
+ e−
+
+ 2H + e
+ 2e
+
Ag + e
−
NO 3
−
−
−
+
+ 4H + 3e
Br2(ℓ) + 2e
−
−
+
O2(g) + 4H + 3e−
+
MnO2 + 4H + 2e
2−
Cr2O 7
+
+ 14H + 6e
Cℓ2(g) + 2e
−
MnO 4
Co
3+
−
−
+ 8H + 5e
+e
F2(g) + 2e−
⇌
Cr
⇌
Cd
−
− 0,41
− 0,40
⇌
Co
− 0,28
⇌
Ni
− 0,25
⇌
Sn
− 0,14
⇌
Pb
− 0,13
− 0,04
⇌
Fe
⇌
H2(g)
⇌
H2S(g)
⇌
Sn
⇌
Cu
⇌
SO2(g) + 2H2O
+ 0,17
⇌
Cu
+ 0,34
0,00
+ 0,14
2+
+ 0,15
+
+ 0,16
⇌
−
4OH
+ 0,40
⇌
S + 2H2O
+ 0,45
⇌
Cu
+ 0,52
⇌
2I−
+ 0,54
⇌
H2O2
+ 0,68
⇌
Fe
⇌
NO2(g) + H2O
+ 0,78
⇌
Hg(ℓ)
+ 0,78
⇌
Ag
+ 0,80
⇌
NO(g) + 2H2O
2+
+ 0,77
−
2Br
⇌
2H2O
⇌
Mn
⇌
⇌
2+
2Cr
3+
+ 1,23
+ 2H2O
+ 1,28
+ 7H2O
+ 1,33
−
+ 1,36
2Cℓ
Mn
2+
2+
⇌
Co
⇌
2F−
19
+ 0,96
+ 1,06
⇌
⇌
+
−
−
− 0,44
2+
+ 4H2O
+ 1,52
+ 1,82
+ 2,87
Increasing reducing ability/Toenemende reduserende vermoë
+
Li + e−
E θ (V)