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PHYSICAL SCIENCE (Second Paper)
NQF LEVEL 4
(10021004)
15 March 2019 (X-Paper) 09:00–12:00
This question paper consists of 15 pages, 3 information sheets and 1 periodic table.
NATIONAL CERTIFICATE (VOCATIONAL)
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TIME: 3 HOURS
MARKS: 150
INSTRUCTIONS AND INFORMATION 1. 2. 3. 4. 5. 6.
Answer ALL the questions. Read ALL the questions carefully. Number the answers according to the numbering system used in this question paper. Use only blue or black ink. Approximate ALL final answers accurately to TWO decimal places. Write neatly and legibly.
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SECTION A QUESTION 1 Give ONE term for each of the following descriptions. Write only the term next to the question number (1.1–1.5) in the ANSWER BOOK.
1.1 Nuclear reaction that occurs in reactors generating electricity. 1.2 Mass per unit volume. 1.3 Physical quantity that indicates the average kinetic energy of the particles in a
substance.
1.4 Process by which nitrogen is extracted from the atmosphere. 1.5 Solution that resists changes in pH when an acid or alkali is added to the
solution. (5 × 1)
[5]
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QUESTION 2 Choose a description from COLUMN B that matches a term in COLUMN A. Write only the letter (A–I) next to the question number (2.1–2.5) in the ANSWER BOOK.
COLUMN A COLUMN B
2.1 2.2 2.3 2.4 2.5
Hydrocarbon Functional group Hydrogen bonding Addition Oxidation
A
B
C
D
E
F
G
H I
encourages the production of strong roots and stems occurs when the rate of the forward reaction equals the rate of the reverse reaction compound made up of carbon, hydrogen and oxygen only type of reaction characteristic of alkenes unstable, intermediate complex formed during the course of a reaction may be a chemical bond, atom or group of atoms that gives an organic compound its characteristic properties responsible for the relatively high boiling point of organic acids compound made up of carbon and hydrogen only occurs when an alkane burns in oxygen
(5 × 1) [5]
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QUESTION 3 Indicate whether the following statements are TRUE or FALSE. Choose the answer and write only 'True' or 'False' next to the question number (3.1–3.5) in the ANSWER BOOK.
3.1 Nuclear power reactors contribute to global warming by producing large
quantities of carbon dioxide.
3.2 Liquids and gases, such as air, are classified as fluids. 3.3 In an endothermic reaction the potential energy of the products is greater than
the potential energy of the reactants.
3.4 A weak base is a strong electrolyte. 3.5 Chemical equilibrium is reached in a closed system when the physical
properties of a chemical system become constant. (5 × 2)
[10]
QUESTION 4 Various options are given as possible answers to the following questions. Choose the answer and write only the letter (A–D) next to the question number (4.1–4.5) in the ANSWER BOOK.
4.1 The graph shows how the radioactivity of a particular isotope varies with time.
What is the half-life of this isotope? A
B C D
2,5 days 5,0 days 10,0 days 12,5 days
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4.2 The equation below represents the reaction that takes place when an organic
compound and concentrated sodium hydroxide are strongly heated. X represents the organic product formed.
CH3CHBrCH3 + NaOH → X + NaBr + H2O Which ONE of the following is the correct IUPAC name for compound X?
A
B C D
Propan-1-ol Propan-2-ol Prop-1-ene Prop-2-ene
4.3 A catalyst has the following properties:
i. It starts a reaction. ii. It is not used up in a chemical reaction. iii. It increases the rate of a chemical reaction. Which ONE of the following is true:
A
B C D
(iii) only (i) and (ii) only (i) and (iii) only (ii) and (iii) only
4.4 Which ONE of the following concerning the reaction in chemical equilibrium
below is true:
N2 (g) + 3H2 (g) 2 NH3 (g) ΔH < 0
A
B C D
Increasing the temperature decreases the concentration of NH3 in the reaction mixture. Decreasing the pressure increases the concentration of NH3 in the equilibrium mixture. Decreasing both pressure and temperature favours the forward reaction. The addition of a catalyst decreases the concentration of NH3 in the reaction mixture.
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4.5 When aqueous solutions of Ag+ and Fe2+ are mixed, Ag and Fe3+ form
according to the following chemical reaction:
Ag+(aq) + Fe2+(aq) Ag(s) + Fe3+(aq)
Which one of the following concentration versus time graphs best represents the way in which the Fe3+ concentration varies as the reaction proceeds to equilibrium?
A
C
B D
(5 × 3)
[15]
TOTAL SECTION A: 35
Time
Fe
3+ c
on
ce
ntr
atio
n
Time F
e3+ c
on
ce
ntr
atio
n
Time
Fe
3+ c
on
ce
ntr
atio
n
Time
Fe
3+ c
on
ce
ntr
atio
n
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QUESTION 5
5.1 Would you expect the hydrostatic pressure at a depth of 50 m in sea water to
be, greater than, equal to or less than at the same depth in fresh water? Explain the answer.
(3) 5.2 A hydraulic press consists of two plungers A and B in contact with a liquid.
The surface area of plunger A in contact with the liquid is 0,1 m2 and the surface area of plunger B in contact with the liquid is 0,35 m2, as shown in the sketch below. A force of 20 N is applied to plunger A in order to hold a block of unknown mass x stationary on plunger B.
5.2.1 Calculate the pressure exerted by plunger A on the surface of the
liquid.
(3) 5.2.2 Is the pressure exerted by the liquid on plunger B, greater than,
equal to or less than the pressure exerted by plunger A on the liquid? Explain the answer with reference to a relevant scientific principle.
(4)
5.2.3 Calculate the mass of block X. (3) [13]
B
A
x
0,1 m2
0,35 m2
20 N
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QUESTION 6 The letters A to F in the table below represent SIX organic compounds.
6.1 Write down the general formula of the homologous series to which compound
A belongs.
(1) 6.2 Is compound B saturated or unsaturated? Give a reason for the answer. (2) 6.3 Write a balanced chemical equation for the complete combustion of
compound C.
(3) 6.4 Write down the structural formula and name of the functional group present in
compound D.
(2) 6.5 Draw the full structural diagram and provide the IUPAC nomenclature of an
isomer of compound E.
(4) 6.6 Select a compound from the list that: 6.6.1 Is a reactant for the formation of polythene 6.6.2 Has a pH less than 7
(2 × 2)
(4)
A
D
B
E
C
butane
F
ethane
H 11
C 11
H 11
C C C H
H 11
H 11 H
11
C C C C
H H
H
H
H
H
H
H H 11
H 11
H 11
C C C O
H H 11
H 11
H
H
C C O H
H O
H
H
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6.7 Give the IUPAC nomenclature for: 6.7.1 Compound A 6.7.2
6.7.3
Compound B Compound D (3 × 2)
(6)
6.8 Explain why compound C has a higher boiling point than compound F. (2)
[24] QUESTION 7 A group of students use the reaction between solid zinc and an excess of hydrochloric acid solution to study two factors which affect the rate of chemical reactions. The reaction between zinc and hydrochloric acid solution is represented by the balanced equation below.
Zn(s) + 2HCℓ(aq) → ZnCℓ2(aq) + H2(g)
Two investigations (A and B) were conducted under the conditions indicated below:
7.1 INVESTIGATION A
7.1.1 Identify the independent variable in this investigation. (1) 7.1.2 Write down a hypothesis for this investigation. (2) 7.1.3 The learners now repeat Experiment 1 using HCℓ of the same
concentration but at a temperature of 30 0C. They find that the rate of the reaction INCREASES. Give an explanation as to why the reaction rate increases.
(3) 7.2 INVESTIGATION B:
Mass of Zn(s)
in g) State of Zn
Concentration of HCℓ (mol∙dm-3)
Temperature of HCℓ (°C)
Experiment 3 1,5 lumps 1,5 24
Experiment 4 1,5 lumps 2,0 24
7.2.1 Write down an investigative question for this investigation. (2) 7.2.2 Is it fair to compare results obtained in Experiment 3 with that in
Experiment 4? Write down only YES or NO and give a reason for the answer.
(2)
Mass of Zn(s)
in g State of Zn
Concentration of HCℓ (mol∙dm-3)
Temperature of HCℓ (°C)
Experiment 1 2,5 powder 1,5 24
Experiment 2 2,5 lumps 1,5 24
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7.2.3 The reactions in experiments 3 and 4 both run to completion. how
will the yield of h2(g) in experiment 3 compare to that in experiment 4? Write down only larger than, smaller than or equal to and give a reason for the answer.
(2) 7.3 The graph below shows changes in the potential energy for the reaction
between zinc and hydrochloric acid. Use the relevant energy values, A, B and C, to write down an expression for each of the following:
7.3.1 Activation energy for the forward reaction. (2) 7.3.2 ∆H for the reverse reaction. (2)
[16]
B
C
A
Course of reaction
Po
ten
tial
en
erg
y (
kJ)
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QUESTION 8
8.1 4 moles of nitrogen dioxide gas (NO2), 4 moles of sulphur dioxide gas (SO2) and 1 mole of sulphur trioxide gas (SO3) are allowed to react in a closed container of volume 2 dm3 at a temperature of 700 oC. The chemical equation for the equilibrium reaction is:
NO2(g) + SO2(g) SO3 (g) + NO(g)
After some time an analysis of the mixture showed that 1,8 moles of SO3 are present in the container.
If the equilibrium constant (Kc) is 9,0 at 700 oC; is the reaction in chemical equilibrium? Show all calculations to justify the answer.
(10)
8.2 Compare the rate of the forward reaction with the rate of the reverse reaction at this unknown time. Write down only equal to, faster or slower.
(2)
8.3 As the temperature increases, the Kc value increases. Is the forward reaction is endothermic or exothermic? With reference to Le Chatelier’s principle explain the answer.
(3) [15]
QUESTION 9 9.1 Ammonium chloride crystals, NH4Cℓ (s), dissolve in water to form ammonium
and chloride ions according to the balanced equation below:
NH4+(aq) + H2O(l) NH3(aq) + H3O
+(aq)
9.1.1 Write down the FORMULA of one conjugate acid/base pair. (2)
9.1.2 Write down the NAME of one ampholyte from the equation. (1)
9.2 9.2.1 A sea shell consists of 80 % calcium carbonate crystals. A sample
of mass x g of this sea shell was dissolved in 200 cm3 hydrochloric acid of concentration 1,5 mol.dm-3. The hydrochloric acid is in excess.
CaCO3 + 2HCℓ CaCℓ2 + H2O
Calculate the number of moles of hydrochloric acid in which the sample is dissolved.
(3)
9.2.2 In a titration, 25 cm3 of the excess hydrochloric acid solution is titrated with a 0,12 mol.dm-3 sodium hydroxide solution. At the end point it was found that 20 cm3 of the sodium hydroxide was used to neutralise the hydrochloric acid solution according to the following balanced equation: HCℓ (aq) + NaOH(aq) NaCℓ (aq) + H2O(l) Calculate the mass x (in grams) of the sea-shell sample used.
(8) [14]
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QUESTION 10 10.1 The flow diagram below shows the processes involved in the production of
fertilizer R. Write down the:
10.1.1 NAME of process P. (1) 10.1.2 NAME and FORMULA of product Q. (2) 10.1.3 FORMULA of fertiliser R. (1) 10.2 A 10 kg bag of NPK (40) fertiliser has an unknown NPK ratio. The mass of
nitrogen is 2,05 kg and the mass of phosphorus is 0,25kg.
10.2.1 What is the meaning of (40) on the label? (1) 10.2.2 Calculate the NPK ratio of the bag of fertiliser. (5)
[10]
PROCESS P CONTACT PROCESS
NH3 Q
FERTILISER R
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QUESTION 11 A voltaic cell was constructed by connecting a chromium half-cell to a metal Y half-cell as shown in the sketch below. In the external circuit electrons flow from the chromium electrode to metal Y. The initial voltmeter reading was 1,54 V.
11.1 Name TWO standard conditions for a voltaic cell. (2) 11.2 11.3
Explain the function of the salt bridge. Name a suitable chemical for use in the salt bridge.
(2) (1)
11.4 Is the net cell reaction exothermic or endothermic? (1) 11.5 When the cells delivers a current, will the concentration of Cr3+ increase,
decrease or remain constant? Write a balanced, half-reaction to explain the answer.
(3) 11.6 Identify metal Y. Clearly show all calculations. (4) [13]
Metal Y
Salt bridge
Cr3+ (aq)
Chromium electrode
V
Y+ (aq)
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QUESTION 12 A radioactive source is placed in a cylindrical hole drilled in a lead block. The radiation produced passes between TWO oppositely charged, parallel metal plates before striking a photographic plate.
12.1 Define radioactivity. (2) 12.2 Give TWO uses of nuclear radiation. (2 × 1) (2) 12.3 Identify the type of radiation indicated by each of the following: 12.3.1 Q 12.3.2 R
(2 × 2)
(4) 12.4 Why is the radioactive material placed in a lead block? (2) [10]
TOTAL SECTION B: GRAND TOTAL:
115 150
Photographic plate
Positively charged plates
Negatively charged plates Negatively charged plates
R
P
Q
Radioactive material
Lead block
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INFORMATION SHEET 1 TABLE 1: PHYSICAL CONSTANTS
NAME SYMBOL VALUE
Standard pressure p 1,013 × 105 Pa
Molar gas volume at STP Vm 22,4 dm3∙mol-1
Standard temperature T 273 K
TABLE 2: FORMULAE
M
mn
V
nc
OR
MV
mc
q = I t W = Vq
θ
anode
θ
cathode
θ
cell EEE
OR
θ
oxidation
θ
reduction
θ
cell EEE
OR
θ
agent reducing
θ
agent oxidising
θ
cell EEE
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INFORMATION SHEET 2
STANDARD REDUCTION POTENTIALS
Half-reactions θE (V) F2(g) + 2e ⇌ 2F + 2,87
Co3+
+ e ⇌ Co2+
+ 1,81
H2O2 + 2H+ +2e ⇌ 2H2O + 1,77
MnO
4 + 8H+ + 5e ⇌ Mn
2+ + 4H2O + 1,51
Cℓ2(g) + 2e ⇌ 2Cℓ
+ 1,36
Cr2O2
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 ⇌ NO(g) + 2H2O + 0,96
Hg2+
+ 2e ⇌ Hg(ℓ) + 0,85
Ag+ + e ⇌ Ag + 0,80
NO
3 + 2H+ + e ⇌ NO2(g) + H2O + 0,80
Fe3+
+ e ⇌ Fe2+
+ 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
SO2
4 + 4H+ + 2e ⇌ SO2(g) + 2H2O + 0,17
Cu2+
+ e ⇌ Cu+ + 0,16
Sn4+
+ 2e ⇌ Sn2+
+ 0,15
S + 2H+ + 2e
⇌ H2S(g) + 0,14
2H+ + 2e ⇌ H2(g) 0,00
Fe3+
+ 3e ⇌ Fe 0,06
Pb2+
+ 2e ⇌ Pb 0,13
Sn2+
+ 2e ⇌ Sn 0,14
Ni2+
+ 2e ⇌ Ni 0,27
Co2+
+ 2e ⇌ Co 0,28
Cd2+
+ 2e ⇌ Cd 0,40
Cr3+
+ e ⇌ Cr2+
0,41
Fe2+
+ 2e ⇌ Fe 0,44
Cr3+
+ 3e ⇌ Cr 0,74
Zn2+
+ 2e ⇌ Zn 0,76
2H2O + 2e ⇌ H2(g) + 2OH 0,83
Cr2+
+ 2e ⇌ Cr 0,91
Mn2+
+ 2e ⇌ Mn 1,18
Aℓ3+
+ 3e ⇌ Aℓ 1,66
Mg2+
+ 2e ⇌ Mg 2,36
Na+ + e ⇌ Na 2,71
Ca2+
+ 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
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(10021004) NC2330(E)(M15)V
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INFORMATION SHEET 3
STANDARD REDUCTION POTENTIALS
Half-reactions θE (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
Cr2+
+ 2e ⇌ Cr 0,91
2H2O + 2e ⇌ H2(g) + 2OH 0,83
Zn2+
+ 2e ⇌ Zn 0,76
Cr3+
+ 3e ⇌ Cr 0,74
Fe2+
+ 2e ⇌ Fe 0,44
Cr3+
+ e ⇌ Cr2+
0,41
Cd2+
+ 2e ⇌ Cd 0,40
Co2+
+ 2e ⇌ Co 0,28
Ni2+
+ 2e ⇌ Ni 0,27
Sn2+
+ 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
Sn4+
+ 2e ⇌ Sn2+
+ 0,15
Cu2+
+ e ⇌ Cu+ + 0,16
SO2
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 ⇌ Mn
2+ + 2H2O + 1,23
O2(g) + 4H+ + 4e
⇌ 2H2O + 1,23
Cr2O2
7 + 14H+ + 6e ⇌ 2Cr
3+ + 7H2O + 1,33
Cℓ2(g) + 2e ⇌ 2Cℓ
+ 1,36
MnO
4 + 8H+ + 5e ⇌ Mn
2+ + 4H2O + 1,51
H2O2 + 2H+ +2 e ⇌ 2H2O + 1,77
Co3+
+ e ⇌ Co2+
+ 1,81
F2(g) + 2e ⇌ 2F + 2,87
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PERIODIC TABLE OF ELEMENT
1 (I)
2 (II)
3
4
5
6
7
8
9
10
11
12
13 (III)
14 (IV)
15 (V)
16 (VI)
17 (VII)
18 (VIII)
2,1
1
H 1
2
He 4
1,0
3
Li 7
1,5
4
Be 9
2,0
5
B 11
2,5
6
C 12
3,0
7
N 14
3,5
8
O 16
4,0
9
F 19
10
Ne 20
0,9
11
Na 23
1,2
12
Mg 24
1,5
13
Aℓ 27
1,8
14
Si 28
2,1
15
P 31
2,5
16
S 32
3,0
17
Cℓ 35,5
18
Ar 40
0,8
19
K 39
1,0
20
Ca 40
1,3
21
Sc 45
1,5
22
Ti 48
1,6
23
V 51
1,6
24
Cr 52 1
,5 25
Mn 55
1,8
26
Fe 56
1,8
27
Co 59
1,8
28
Ni 59
1,9
29
Cu 63,5
1,6
30
Zn 65
1,6
31
Ga 70
1,8
32
Ge 73
2,0
33
As 75
2,4
34
Se 79
2,8
35
Br 80
36
Kr 84
0,8
37
Rb 86
1,0
38
Sr 88
1,2
39
Y 89
1,4
40
Zr 91
41
Nb 92
1,8
42
Mo 96
1,9
43
Tc
2,2
44
Ru 101
2,2
45
Rh 103
2,2
46
Pd 106
1,9
47
Ag 108
1,7
48
Cd 112
1,7
49
In 115
1,8
50
Sn 119
1,9
51
Sb 122
2,1
52
Te 128
2,5
53
I 127
54
Xe 131
0,7
55
Cs 133
0,9
56
Ba 137
57
La 139
1,6
72
Hf 179
73
Ta 181
74
W 184
75
Re 186
76
Os 190
77
Ir 192
78
Pt 195
79
Au 197
80
Hg 201
1,8
81
Tℓ 204
1,8
82
Pb 207
1,9
83
Bi 209
2,0
84
Po
2,5
85
At
86
Rn
0,7
87
Fr
0,9
88
Ra 226
89
Ac
58
Ce 140
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
90
Th 232
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
Approximate relative atomic mass
Atomic number
29
Cu 63,5
1,9
Symbol
Electronegativity
KEY
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