TEST CODE
FORM TP 2011005
CARIBBEAN
01212020
JANUARY 2011
E XAM I NAT I O N S
COUNCIL
SECONDARY EDUCATION CERTIFICATE
EXAMINATION
CHEMISTRY
Paper 02 – General Proficiency
2 hours and 30 minutes
READ THE FOLLOWING DIRECTIONS CAREFULLY.
1.
This paper consists of SIX compulsory questions in THREE sections.
2.
Write your answer to EACH question in the space provided in this answer
booklet.
3.
Where appropriate, ALL WORKING MUST BE SHOWN in this booklet.
4.
Return this booklet at the end of the examination.
5.
The use of silent, non-programmable calculators is allowed.
DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO SO.
Copyright © 2010 Caribbean Examinations Council.
All rights reserved.
01212020/JANUARY/F 2011
- 2 SECTION A
Answer ALL questions in this section.
Write your answers in the spaces provided in this booklet.
Do NOT spend more than 30 minutes on Question 1.
1.
It is possible to determine the end point of an acid-base reaction by measuring the temperature
changes when different volumes of a strong acid react with a strong base. Table 1 shows the
volumes of sulphuric acid used to react with 25 cm3 of 2.0 mol dm-3 sodium hydroxide and the
temperature changes that occurred. Figure 1 shows the thermometer readings for the addition
of 10 cm3 and 20 cm3 of the H2SO4.
TABLE 1: EXPERIMENTAL RESULTS
Volume of H2SO4 Added
(cm3)
0
3
6
10
15
20
25
Temperature
(°C)
22.5
29.5
36.0
38.0
13.5
40 C
Figure 1. Thermometer readings for acid-base reactions
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- 3 -
45
40
35
20
15
10
5
10
12
14
16
18
20
22
24
26
Volume of H 2S04 (cm3)
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- 4 (a)
(i)
Differentiate between a ‘strong acid’ and a ‘weak acid’.
_______________________________________________________________
_______________________________________________________________
( 2 marks)
(ii)
Suggest ONE other base that could be used instead of NaOH.
_______________________________________________________________
( 1 mark )
(iii)
Using the thermometer readings in Figure 1, complete Table 1 by recording the
temperature for the addition of 10 cm3 and 20 cm3 of the H2SO4.
( 2 marks)
(iv)
Plot the points for temperature against volume of acid added using the axes on
page 3.
( 3 marks)
(v)
Draw the TWO lines of best fit through the points in (iv) above where the
temperature is increasing and where the temperature is decreasing and hence
determine the end point of the reaction.
Volume of H2SO4 at end point ______________________________________
( 3 marks)
Write a balanced equation for this reaction.
(vi)
_______________________________________________________________
( 2 marks)
(vii)
Calculate the number of moles of NaOH used in the reaction.
_______________________________________________________________
_______________________________________________________________
( 1 mark )
(viii)
Calculate the concentration of H2SO4 in mol dm –3.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
( 2 marks)
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- 5 (b)
Paul conducted two experiments in the laboratory to identify carbon dioxide and
ammonia. Figure 2 shows the experimental arrangement of the procedures that he used
to test for the gases.
Test for Ammonia
Test for Carbon Dioxide
d(
Damp red litmns
Ammonium nitrate
Calcium
aod dilute
Solution X
sodium hydroxide
nitric acid
Figure 2. Experimental arrangement for testing of gases
(i)
Identify Solution X.
_______________________________________________________________
( 1 mark )
(ii)
Identify ONE flaw in the procedure that Paul used for carrying out EACH test.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
( 2 marks)
(iii)
Write a balanced equation for the reaction occurring in Tube 1.
Balanced equation:
_______________________________________________________________
( 2 marks)
(iv)
Explain why nitric acid instead of sulphuric acid is used in the experiment in
Tube 1 in order to obtain a positive test result.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
( 4 marks)
Total 25 marks
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- 6 2.
A group of students set up Experiments I and II as shown in Figure 3.
Figure 3. Diagrams of Experiments I and II
(a)
(i)
What changes would be observed in Beakers A and B over a 24-hour period?
_______________________________________________________________
_______________________________________________________________
( 2 marks)
(ii)
How do the changes in Beaker A differ from that in Beaker B?
_______________________________________________________________
_______________________________________________________________
( 1 mark )
(iii)
Account for any differences in the observations in (a) (ii) above.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
( 3 marks)
(b)
The students conducted a third experiment, Experiment III, to determine the heat of
solution of ammonium nitrate by mixing 8 g of ammonium nitrate with 50 cm3 water at
room temperature. The temperature before and after the ammonium nitrate was added
to the water is given as:
Initial temperature = 27°C
Final Temperature = 19°C
(i)
State whether the process in Experiment III is exothermic or endothermic.
The process is ________________________________________________ .
( 1 mark )
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- 7 (ii)
Draw a labelled energy profile diagram to show the heat changes involved in
Experiment III.
( 3 marks)
(iii)
Calculate the heat change when 8 g of ammonium nitrate is dissolved in 50 cm3
of water.
[Relative Atomic Mass: N = 14; H = 1; O = 16; the specific heat capacity of the
solution is 4.2 kJ kg-1 K-1; density of water is 1.0 g cm–3]
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
( 2 marks)
(iv)
State ONE assumption necessary in your calculation in (b) (iii) above.
_______________________________________________________________
( 1 mark )
(v)
From your answer to (b) (iii), calculate the heat change when 1 mole of
ammonium nitrate dissolves in water.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
( 2 marks)
Total 15 marks
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- 8 3.
(a)
Compound A (C3H6) and Compound B (C3H8) are hydrocarbons. Draw the FULLY
displayed structures and state the names of BOTH compounds.
Compound A
Compound B
Name: _____________________
(b)
Name: ______________________
( 4 marks)
One of these compounds reacts with bromine dissolved in trichloroethane.
(i)
State the observation for this reaction.
Observation: ____________________________________________________
( 1 mark )
Write a chemical equation for this reaction.
(ii)
Equation: ______________________________________________________
( 2 marks)
Draw the FULLY displayed structure of the product in the equation in (b) (ii)
above and state the name of this product.
(iii)
Structure
Name: _________________________________________
( 2 marks)
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- 9 (c)
The fully displayed structures of Compounds X, Y and Z are shown below:
X
Y
Z
(i)
Write the names of the homologous series to which EACH of these three
compounds belongs.
Compound X: ___________________________________________________
Compound Y: ___________________________________________________
Compound Z: ___________________________________________________
( 3 marks)
(ii)
State which TWO of these compounds are soluble in water, and give a reason
for your choice.
TWO compounds: ____________________ and _____________________.
( 2 marks)
Reason: _______________________________________________________
_______________________________________________________________
_______________________________________________________________
( 1 mark )
Total 15 marks
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01212020/JANUARY/F 2011
- 10 SECTION B
Answer ALL questions in this section.
Write your answers in the space provided after EACH question in this answer booklet.
4.
(a)
The production of sugar from sugar cane is important to the Caribbean economy. The
process of extracting sucrose from the juice of sugar cane involves several steps. Two
of these steps are:
(i)
Clarifying
(ii)
Crystallizing
Outline what happens in EACH step.
(b)
( 4 marks)
Table 2 shows selected properties of four Group II elements.
TABLE 2: ATOMIC RADII AND IONISATION ENERGIES
OF SOME GROUP II ELEMENTS
Group II Element
Magnesium
Calcium
Strontium
Barium
Atomic Radius (pm)
160
197
215
217
Ionisation Energy (kJ mol–1)
747
596
558
512
(i)
Outline the reason for the change in atomic radius from magnesium to barium.
( 2 marks)
Barium reacts more readily with water than magnesium does. With reference
to the data in Table 2, explain this observation.
( 2 marks)
(ii)
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- 11 (c)
Two samples of aqueous sodium bromide are treated with chlorine gas and solid iodine
as shown in Experiments 1 and 2 in Figure 4.
CJ,(g) in
Sodium bromide solution -+-
Experiment 1: Bubbling chlorine gas
into an aqueous solution of sodium bromide
---+-Iodine
Experiment 2: Stirring solid iodine
in an aqueous solution of sodium
bromide
Figure 4. Experiments 1 and 2
(d)
( 2 marks)
(i)
State whether a reaction would take place in EACH case.
(ii)
Write a balanced equation, where appropriate, for the reaction occurring in
(c) (i) above.
( 2 marks)
Sodium oxide and sulphur dioxide were each dissolved in water to form colourless
solutions.
(i)
Describe a test that can be used to identify the solution formed with sulphur
dioxide.
( 2 marks)
(ii)
Write a balanced equation to support the use of this test.
( 1 mark )
Total 15 marks
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- 12 Write your answer to Question 4 here.
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- 13 Write your answer to Question 4 here.
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- 14 5.
(a)
Sulphuric acid is prepared industrially via the Contact Process represented in Figure 5.
Figure 5. Schematic diagram of the Contact Process
(i)
(b)
Describe the processes involved in converting sulphur to sulphur trioxide. In
your response,
a)
identify A from Figure 5
b)
include TWO balanced chemical equations for the reactions taking place
at Steps I and II
c)
include the necessary reaction conditions for Step II.
( 8 marks)
(ii)
Explain why concentrated H2SO4 is used instead of pure water in Step III of
Figure 5.
( 2 marks)
(iii)
When sulphur trioxide gets into the atmosphere, it can form acid rain which can
destroy buildings made from limestone. Write an ionic equation which BEST
represents the chemical reaction taking place when acid rain reacts with limestone.
( 2 marks)
Study Figure 6 which shows the structures of graphite and diamond.
Graphite
Diamond
Figure 6. Structures of graphite and diamond
With reference to this figure, explain why diamond is used for cutting and graphite is
not.
( 3 marks)
Total 15 marks
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- 15 Write your answer to Question 5 here.
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- 16 Write your answer to Question 5 here.
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01212020/JANUARY/F 2011
- 17 SECTION C
Answer this question.
Write your answer in the space provided after the question in this booklet.
6.
(a)
Starch is a major constituent of wheat flour. Identify ONE OTHER major constituent
of wheat flour.
( 1 mark )
(b)
Baking powder and yeast can both be used as raising agents in bread making.
(i)
State ONE similarity and ONE difference in the way they act as raising agents.
( 3 marks)
(ii)
Explain how the action of yeast during bread-making causes the dough to rise.
Include TWO chemical equations and the reaction conditions.
( 6 marks)
(c)
Tamarinds grown in the Caribbean are a good source of Vitamin C which is acidic. They
can be used as tamarind drinks or as stewed tamarinds. When preparing tamarind drink,
sodium hydrogen carbonate, NaHCO3, is often added. However, this is not necessary
when stewing tamarinds. Suggest a possible explanation for this practice. Write ONE
chemical equation to support this practice.
( 5 marks)
Write your answer to Question 6 here.
Total 15 marks
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- 18 Write your answer to Question 6 here.
END OF TEST
01212020/JANUARY/F 2011