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Section
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else or allow another candidate to copy from you, or if you cheat in any other way, you may be disqualified.
Candidate Declaration. I have read and understood the Notice to Candidate and can confirm that
I have produced the attached work without assistance other than that which is acceptable under the scheme
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Signature
Mark
PSA
Task
Section A
Date
Section B
General Certificate of Education
Advanced Subsidiary Examination
June 2013
Chemistry
Unit 3T
TOTAL
ISA MARK
(max 50)
CHM3T/Q13/test
AS Investigative Skills Assignment
Written Test
For submission by 15 May 2013
For this paper you must have:
l the Periodic Table/Data Sheet provided at the end of this paper
l your Task Sheet and your Candidate Results Sheet
l a ruler with millimetre measurements
l a calculator.
Time allowed
l 1 hour
Instructions
l Use black ink or black ball-point pen.
l Fill in the boxes at the top of this page.
l Answer all questions.
l You must answer the questions in the spaces provided. Do not
write outside the box around each page or on blank pages.
l Do all rough work in this book. Cross through any work you do not
want to be marked.
Information
l The marks for questions are shown in brackets.
l The maximum mark for this paper is 30.
l You are expected to use a calculator, where
appropriate.
l You will be marked on your ability to:
– organise information clearly
– use scientific terminology accurately.
Details of additional assistance (if any). Did the candidate receive any help or information in the production of this
work? If you answer yes give the details below or on a separate page.
Yes
No
Teacher Declaration:
I confirm that the candidateʼs work was conducted under the conditions laid out by the specification. I have authenticated the
candidateʼs work and am satisfied that to the best of my knowledge the work produced is solely that of the candidate.
Signature of teacher ................................................................................................................... Date ..........................................
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WMP/Jun13/CHM3T/Q13/test
CHM3T/Q13/test
Do not write
outside the
box
2
Section A
These questions are about the task, to investigate how changes in the concentration of sodium
thiosulfate solution affect its rate of reaction with dilute hydrochloric acid.
You should use your Task Sheet and your Candidate Results Sheet to answer these questions.
Answer all questions in the spaces provided.
1
Complete Table 1. You should transfer from your Candidate Results Sheet the time
taken in seconds (t) for the X to disappear from view in each of the five experiments.
You should also calculate and record a value for 1000 for each of the five
t
concentrations of sodium thiosulfate.
Record each value of 1000
to an appropriate precision.
t
Table 1
Concentration of
Na2S2O3(aq) / mol dm–3
0.04
0.08
0.12
0.16
0.20
t/s
1000
t
(3 marks)
1000
t
2
Plot a graph of
3
Draw a line of best fit on your graph.
4
Use your graph to complete Table 2.
(y-axis) against concentration of Na2S2O3 on the grid opposite.
(4 marks)
(2 marks)
Table 2
Concentration of Na2S2O3(aq) / mol dm–3
1000
t
0.05
0.10
(2 marks)
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4
5
Define the term rate of reaction.
1000
Explain why it is possible to use the formula t as a measure of the rate of this
reaction.
............................................................................................................................................
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(2 marks)
6
Collision theory is used to explain why, at a constant temperature, the rate of this
reaction doubles when the concentration of sodium thiosulfate is doubled and the
concentration of hydrochloric acid is kept constant.
Use the data from Table 2 in Question 4 to state whether or not your results are good
enough to support this theory. Use the collision theory, as appropriate, to explain your
conclusion.
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(2 marks)
WMP/Jun13/CHM3T/Q13/test
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5
7
Predict which one of the five experiments in the Task leads to the least reliable rate.
Give one reason for your answer.
............................................................................................................................................
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............................................................................................................................................
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(2 marks)
8
The error in using a 50 cm3 measuring cylinder is ± 1.0 cm3.
Calculate the maximum percentage error in using this apparatus when measuring
50 cm3 of solution.
............................................................................................................................................
............................................................................................................................................
(1 mark)
9
Use information from the equation and your knowledge of the experiment to deduce
two reasons why the hazard associated with the formation of sulfur dioxide in this
investigation might be considered to be low.
Na2S2O3(aq) + 2HCl(aq)
2NaCl(aq) + S(s) + SO2(aq) + H2O(I)
Reason 1 ............................................................................................................................
............................................................................................................................................
............................................................................................................................................
Reason 2 ............................................................................................................................
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............................................................................................................................................
(2 marks)
20
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6
Section B
Answer all questions in the spaces provided.
The questions in this section concern the rates of some reactions of Group 2 metals.
10
In an investigation of the rate of reaction between hydrochloric acid and pure
magnesium, a student obtained the following curve.
Rate of reaction
/ mol dm–3 s–1
Concentration of acid / mol dm–3
The reaction of magnesium with dilute hydrochloric acid is exothermic.
Use your understanding of collision theory to explain why the student did not obtain a
straight line.
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(3 marks)
WMP/Jun13/CHM3T/Q13/test
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7
11
The magnesium used in a laboratory experiment was supplied as a ribbon. The ribbon
was stored in an open plastic bag exposed to the air.
Explain why it is important to clean the surface of this magnesium ribbon when
investigating the rate of its reaction with hydrochloric acid.
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(2 marks)
12
Magnesium ribbon reacts with hot water. Heated magnesium ribbon reacts with steam.
State two differences between these reactions.
Difference 1 ........................................................................................................................
............................................................................................................................................
Difference 2 ........................................................................................................................
............................................................................................................................................
(2 marks)
13
Pure magnesium reacts completely with an excess of dilute sulfuric acid.
The reaction of pure calcium with an excess of dilute sulfuric acid is very rapid initially.
This reaction slows down and stops before all of the calcium has reacted.
Use your knowledge of the solubilities of Group 2 sulfates to explain why these
reactions of magnesium and calcium with dilute sulfuric acid are so different.
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(3 marks)
END OF QUESTIONS
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WMP/Jun13/CHM3T/Q13/test
l
GCE Chemistry Data Sheet
l
8
WMP/Jun13/CHM3T/Q13/test
(3)
89
actinium
† 90 – 103 Actinides
Lanthanides
88
87
* 58 – 71
Ra
radium
Fr
francium
57
[227]
Ac †
56
[226]
55
[223]
La *
lanthanum
Ba
barium
Cs
caesium
39
138.9
38
137.3
37
132.9
104
rutherfordium
Rf
[267]
72
hafnium
Hf
178.5
40
Zr
zirconium
Y
Sr
strontium
Rb
rubidium
91.2
yttrium
21
88.9
20
87.6
19
85.5
22
Ti
titanium
Sc
Ca
calcium
K
potassium
(4)
47.9
(5)
(6)
(7)
Mn
54.9
25
Tc
[98]
43
Pr
Ce
(8)
(9)
(10)
Pt
77
(11)
Sm
150.4
109
Pa
protactinium
91
Th
thorium
90
U
92
uranium
93
neptunium
Np
[237]
61
94
plutonium
Pu
[244]
62
60
238.0
59
231.0
58
78
Ds
[281]
Rg
[280]
79
gold
Au
197.0
47
silver
Ag
107.9
29
copper
Cu
63.5
95
americium
Am
[243]
63
europium
Eu
152.0
110
96
curium
Cm
[247]
64
gadolinium
Gd
157.3
111
meitnerium darmstadtium roentgenium
Mt
[276]
platinum
Ir
iridium
195.1
46
palladium
Pd
106.4
28
nickel
Ni
58.7
192.2
45
rhodium
Rh
102.9
27
cobalt
Co
58.9
samarium
Pm
[145]
108
hassium
Hs
[270]
76
osmium
Os
190.2
44
ruthenium
Ru
101.1
26
iron
Fe
55.8
praseodymium neodymium promethium
232.0
cerium
144.2
140.9
140.1
Nd
107
bohrium
Bh
[272]
75
rhenium
Re
186.2
106
seaborgium
Sg
[271]
74
tungsten
W
183.8
42
molybdenum technetium
Mo
96.0
24
chromium manganese
Cr
52.0
105
dubnium
Db
[268]
73
tantalum
Ta
180.9
41
niobium
Nb
92.9
23
vanadium
V
50.9
(12)
97
berkelium
Bk
[247]
65
terbium
Tb
Ge
49
81
thallium
Tl
204.4
82
lead
Pb
207.2
50
tin
Sn
In
indium
118.7
32
germanium
114.8
31
gallium
Ga
14
72.6
13
69.7
83
bismuth
Bi
209.0
51
antimony
Sb
121.8
33
arsenic
As
15
74.9
phosphorus
P
31.0
7
nitrogen
N
14.0
(15)
84
polonium
Po
[209]
52
tellurium
Te
127.6
34
selenium
Se
16
79.0
sulfur
S
32.1
8
oxygen
O
16.0
(16)
85
astatine
At
[210]
53
iodine
I
126.9
35
bromine
Br
17
79.9
chlorine
Cl
35.5
9
fluorine
F
19.0
(17)
86
radon
Rn
[222]
54
xenon
Xe
131.3
36
krypton
Kr
18
83.8
argon
Ar
39.9
10
neon
Ne
2
20.2
Es
[252]
67
holmium
Ho
164.9
98
99
californium einsteinium
Cf
[251]
66
dysprosium
Dy
162.5
100
fermium
Fm
[257]
68
erbium
Er
167.3
101
mendelevium
Md
[258]
69
thulium
Tm
168.9
102
nobelium
No
[259]
70
ytterbium
Yb
173.1
103
lawrencium
Lr
[262]
71
lutetium
Lu
175.0
Elements with atomic numbers 112-116 have been reported but
not fully authenticated
158.9
80
mercury
Hg
200.6
48
cadmium
Cd
112.4
30
zinc
Zn
65.4
Si
silicon
aluminium
Al
6
28.1
27.0
5
C
atomic (proton) number
scandium
45.0
12
40.1
11
39.1
Mg
magnesium
Na
sodium
4
24.3
3
23.0
B
12.0
carbon
Be
beryllium
Li
lithium
10.8
boron
symbol
9.0
6.9
(14)
helium
1
(13)
(18)
0
hydrogen
7
4.0
6
He
5
H
4
1.0
3
name
relative atomic mass
(2)
(1)
Key
2
1
The Periodic Table of the Elements
9
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