rESr coDE
FORM TP 2023005
JANUARY 2023
CARIBBEAN
EXAMINATIONS
CARIBBE AI{
ONDARY E DU CATION
EXAMINATION
SE C
012120201
COUNCIL
CE RTIT' TCATH,!!
CHEMISTRY
Paper 02
- General
Proficiency
2 ltours 30 minutes
RSAD THE T'OLLOWING INSTRUCTIONS CAREFULLY.
1.
This paper consists of SIX questions in TWO sections. Answer ALL questions.
2.
Write your answers in the spaces provided in this booklet.
3.
Do NOT write in the margins.
4.
Where appropriate,
5.
You may use a silent, non-programmable calculator to answer questions.
ALL WORKING MUST BE SHOWN inthis booklet.
6. If you need to rewrite
any answer and there is not enough space to do so on the
original page, you must use the extra lined page(s) provided at the back of this
booklet. Remember to draw a line through your original answer.
7. If you use the extra page(s) you MUST write
the question number clearly in
the box provided at the top of the extra page(s) and, where relevant, include
the question pari beside the answer.
DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO SO.
Copyright @ 2A19 Caribbean Examinations Council
All rights reserved.
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-5SECTION A
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AnswerALL questions.
DO NOT spend more than 30 minutes on Question
(a)
1.
1.
Students were required to prepare a sample of the normal salt produced when aqueous
sodium hydroxide reacts with dilute sulfuric acid.
(i)
Define the term 'normal salt'.
(2 marks)
(ii)
Identifl, ONE other type of salt that can be formed from the reaction between
dilute sulfuric acid and aqueous sodium hydroxide.
(1 mark)
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-6(b)
The normal salt was produced by conductiflg
a dilute solution
of
a
titration' The students were provided with
4'9 g dm-' of sulfuric acid
5 g of sodium hYdroxide
methyl orange indicator'
A and B' The titration results for Parl A
They carried out the procedure outlined in Parts
are presented in Figure 1'
of a normal salt and answer the
Review the procedure in Part A for the preparation
questions that follow.
Part A
-
Procedure
1.
the volumetric ffask and add distilled water
Place 5 g of sodium hydroxide solution in
2.
and transfer the solution to
Pipette 25 cm3of thp sodium hydroxide solution
flask.
a
sodium hydroxide solution in the
Add 2 droPs of methYl orange indicator to the
to make 250 cm3 of solution'
a
conical
conical flask.
4.
solution until
place the sulfuric acid in the burette and titrate the sodium hydroxide
the end point is reached.
5.
obtained'
Repeat Steps 2-4 until consistent results are
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Initial
Titration
Final
Initial
Final
Titration
1
2
(Rough)
Figure 1. Burette readings
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(D
Complete Table
1
-
by using the readings shown in Figure 1 on page 6.
TABLE 1: TITRATION OF SODIUM HYDROXIDE SOLUTION
WITH SULFURIC ACID
Burette Reading/cm3
Titration
1
Titration
2
Titration
3
Final reading
initial reading
Volume of acid used
(9 marks)
(ii)
(iii)
In Table 1, indicate using asterisks (*), the titration volumes that will be used to
(1 rnark)
calculate the average volume of sulfuric acid.
Calculate the average volume of sulfuric acid used in the titration.
(1 mark)
(iv)
Part B
Complete the procedure for Part B by stating the steps required to obtain a dry
sample of the normal salt.
-
Procedure
1.
Pipette 25 cm3 of the sodium hydroxide solution and transfer the solution to a
conical flask.
2.
Using the burette, add the volume of sulfuric acid used to neutralize the base from
Part A to the sodium hydroxide solution in the conical flask.
J.
4.
(2 marks)
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-8(v)
formation of the normal
write a balanced equation, including state symbols, for the
salt from sulfuric acid and sodium hydroxide'
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(vi)
neutralize the sodium hydroxide'
calculate the number of moles of sulfuric acid used to
(MolarmaSS:sulfuricacid:98g/mol;sodiumhydroxide:40gimol)
(2 marks)
(vii)
reaction'
calculate the mass of the normal salt expected from the
:32')
S
(R.A.M. Na =23 A: 16;
is'*utrtO
(viii)
g' Suggest oNE possible
The actual mass of salt obtained by the student was 0.09
salt and the mass obtained'
reason for the difference in the expected mass of the
(1 mark)
Total25 marks
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-9MAII{ active ingredients in chlorine bleach is the oxidizing agent, sodium hypochlorite
(NaClO). By adding sodium hypochlorite to water, hypochlorous acid (HOCI) is formed,
One ofthe
according to the equation below.
NaCIO + H2O --+ HOCI + NaOH
(a)
State ONE use of bleach in the laundering of clothing.
(1 mark)
(b)
Define EACH of the following terms.
(i)
Oxidizing agent
(1 mark)
(ii)
Oxidation
(1 mark)
(c)
Deduce the oxidation number of Cl in the fonnula NaClO.
(3 rnarks)
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acid (HOCI) as shown in the
hypochlorous.
Chlorine gas also reacts with water to form
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of Cl for the process?
What is the change in oxidation number
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(2 marks)
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(ii)
Whichprocessoccurredwhenthechlorinegas'Cl,'becameachlorineion'Cl-?
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(1 rnark)
(iii)
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gas'
Describe a simple laboratory test for chlorine
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(2 marks)
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A more natural altemative to chlorine bleach is the use of detergents which release hydrogen
peroxide in water. The bleaching action of hydrogen peroxide is also a redox reaction and
is represented by the foliowing equation.
zHrar@g)'-+ ZHra(l + Or(g)
'+r--
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During one stage of the reaction, Hr0r(ad is converted to HrO(/). Show the changes in
the oxidation number for oxygen in HrO,(aq) and HrO(/), and deduce whether this is an
oxidation or reduction reaction.
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(4 marks)
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(a)
the term
Cracking is a very important process in the petroleum industry. What is meant by
'cracking'?
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(b)
CompoundA (C4H8) and Compound B (C4H10) are both hydrocarbons that can be obtained
from cracking'
(i)
(ii)
State the names of Compound A and Compound
ComPound
A
ComPound
B'........"...
B'
."...........
(2 marks)
Draw the FULLY displayed structure of Compound A'
(2 rnarks)
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State the homologous series to which Compound B belongs.
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(1 mark)
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(iv)
r'Er:
Describe briefly ONE test that could be used to distinguish between
Compound A and Compound
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(3 marks)
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(c)
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Compound B (CoHrJ can exist as structural isomers.
(i)
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Define the term'structural isomers'.
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(2 marks)
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(ii)
In the space provided below, draw FULLY displayed structures of TWO isomers
of Compound B"
Isomer
1
fsomer 2
(2 marks)
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(d)
Compound A burns in oxygen with a sooty flame.
Write a balanced chemical equation for the complete combustion of Compound A in
excess oxygen.
(2 marks)
Total 15 marks
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AnswerALL questions'
(a)
(i)
of carbon' Define the term'allotrope''
Graphite and diamond are two allotropes
(1 mark)
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(ii)
-
Draw the lattice structures for diamond and graphite.
Diamond
(3 rnarks)
(Jraphite
(3 rnarks)
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(i)
but diamond does
Explain, in terms of bonding, why graphite conducts electricity
not.
(2 marks)
(ii)
Describe the bonding present in metals'
(2 marks)
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(c)
Sodium chloride is solid at room temperature.
(D
Sketch the lattice structure for sodium chloride.
Sodium chloride
(3 marks)
(ii)
Which type of bonding exists in sodium chloride?
(1 mark)
Total 15 marks
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5.
(a)
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Ethene undergoes a halogenation reaction to form 1,2-dibromoethane.
(i)
Draw the FULLY displayed structure of ethene'
Ethene
(2 marks)
(ii)
Write the molecular formula for 1,2-dibromoethane.
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(iii)
-
Draw the FULLY displayed structure of 1,2-dibromoethane.
1,2-dibromoethane
(2 marks)
(iv)
State whether the halogenation of ethene is an addition or substitution reaction.
(1 mark)
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(b)
place in two steps'
Dibromomethane can be obtained from methane" This reaction takes
of
Write balanced chemical equations to show EACH step in the formation
(D
dibromomethane.
Step
1
Step 2
(4 marks)
(i
reaction'
state whether the halogenation of methane is an addition or substitution
i)
(1 mark)
(c)
materials for making
Ethene and propene are $zpical monomers which are used as starting
polymers. fn forming poiy-*.r, ethene and propene undergo addition polymerization'
(i)
Define the term 'PolYmer'.
(1 mark)
(i
i)
Define the tem 'addition polymerization''
(1 mark)
(iii)
State ONE use of EACH of the following polymers'
Polyvinyl chloride
Teflon
(2 marks)
Total 15 marks
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(a)
6.
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The most abundant gas in the air by volume is nitrogen. List ONE physical property and
ONE chemical property of nitrogen.
Physical property
=i
!*i.
Chemical property
(2 marks)
(b)
When gases are produced in a school laboratory, there are THREE main methods in which
they can be collected: upward delivery, downward delivery and displacement of water.
(i)
List the TWO factors that should be considered when choosing an appropriate
method for the collection of gases in the laboratory.
(2 marks)
(i
i)
State which ONE of the three methods is best suited for the collection of ammonia
gas in the laboratory. Explain why EACH of the other two methods would NOT
be appropriate.
(5 marks)
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(c)
-
preparation of dry
Draw a labelled diagram of the apparatus which could be used for the
ammonia in the laboratory.
to be used and the
Ensure that you identify on your diagram the location of the reagents
drying and collection areas of the ammonia gas'
(4 marks)
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01212020lJ1CSEC 2023
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(d)
Ammonia is rnainly used in fertilizers such as ammonium nitrate. Explain how nitrate
fertilizers can be harmful to the environrnent.
(2 marks)
Total 15 marks
END OF TEST
IF YOU FINISH BEFORE TIME IS CALLED, CHECK YOUR WORK ON THIS TBST.
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