TEST CODE
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FORM TP 2010149
O2II2O2O
MAY/JUNE
CARIBBEAN EXAMINATIONS COUNCIL
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ADVANC ED PROFICIENCY EXAMINATION
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CHEMISTRY
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Paper02
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2 hours 30 nfinutes
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This paper consists of sIX compulsory questions in Trwo sections.
Section A consists of THREE structured questions, one from each Module.
Section B consists of THREE extended response questions, one from each
Module.
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For Section A, write your answers in the spaces provided in this booklet.
For
section B, write your answers in the answer uooktet provided.
4.
AII working must be shown.
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The use of silent, non-programmable calculators is permitted.
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A data booklet is provided.
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Copyright O 2008 Caribbean Examinarions Council@.
- reserved'
All rights
2010
2O1O
-2SECTION A
Answer ALL questions in this section.
Write your answers in the spaces provided in this booklet.
MODT]LE
1
FUNDAMENTALS IN CHEMISTRY
1.
(a)
State the types of bonds (intra-molecular and inter-molecular) that exist in liquid
ammonia.
[
(b)
2 marks]
The
Ammonia can be produced by heating calcium oxide with ammonium chloride.
two other products are calcium chloride and water'
(i)
Write a balanced chemical equation for the reaction between calcium oxide and
ammonium chloride-
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[
(ii)
2 marks]
Calculate the mass of ammonium chloride needed to produce 1 dm3 of
ammonia at RTP (room temperature and pressure)'
(Molar volume = 24 dm3 at RTP)
[
2 marks]
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02tt2020lcAPE 2010
-3(c)
(i)
Ammonia gas deviates from ideal behaviour. under which of the following
sets of conditions, I, II or III, would the deviation be LEAST?
Conditions
Temperature ('C)
Pressure (kPa)
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40
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50
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20
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(ii)
I tmark]
State
Two
assumptions of the kineric theory as it pertains to ideal gases.
[
(iii)
which assumption of the kinetic theory as it pertains to ideal
likely account for your answer to (c) (i) above?
2 marks]
gases would
Mosr
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(d)
so--" ammonia gas is dissolved in water. The
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exact concentration of the solution is
unknown and has to be determined. Describe
an experiment that would determine the
concentration of the aqueous ammonia.
[
5 marks]
Total 15 marks
02rr2020/cAPE 2010
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MODTJLE 2
KINETICS AND EQIILIBRIA
2.
(a)
Define EACH of the following terms:
(i)
(ii)
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(b)
Standard electrode potential of a half-cell
[
2
marks]
[
2
marks]
Standard cell potential of an electrochemical cell
a standard copper
Figure 1 is a diagram of an electrochemical cell consisting of
by the notation,
electrode and a standard aluminium electrode, represented
Al(s) | Al3*(aq) llcu'.1aq1 lcu(s).
Solution B
Solution A
aluminium electrodes
Figure 1. An electrochemical cell with standard copper and
(i)
On the diagram in Figure 1, label
a)
b)
c)
the ions in Solution A and Solution B
d)
the direction of electron flow.
the salt bridge
the cathode and anode
[
5 marks]
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o2tr2020lcAPE 2010
-5(ii)
State what would be observed at the cathode after the electrochemical
cell in
Figure t has been running for a few hours.
I lmark]
(iii)
State the experimental conditions used in the preparation of the
cell in Figure
l.
Temperature
Concentration of Solutions A and B
[
(iv)
2 marks]
use the information in your Data Booklet to calculate
the standard cell potential,
E""u, for the electrochemical cell in Figure
1.
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[
Total
02r12020/c,APE 2010
3 marks]
1.5
marks
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-6MODULE
3
CHEMISTRY OF THE ELEMENTS
3.
Ammoniumvanadate(V), NH4VO3, is an orange solid. Tests are performed on NHoVOrto show
the variable oxidation states of vanadium.
(a)
Record in Table 1 the observation expected for EACH of the tests below.
TABLE 1: TESTS ON AMMOMTJM VANADATE(V)
(i)
Inference
Observation
Test
A few cm3 of bench NaOH
Colour:
VOr* formed
is added to a small amount
of solid NH4VO3, followed
by a few cm3 of dilute
H2SO4.
(ii)
A little granulated zinc is
added to the solution in
above.
Colour changes to
Vor*
(i)
then to
v02*
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and VO2*
then to
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v3*
and
finally
\r2+
[
(b)
5 marks]
Calculate the oxidation number of vanadium in EACH of the following species:
(i)
voso"
(ii)
vor*
(iii)
vo2*
t 3 marksl
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o2rr2020lcAPE 2010
-7
(c)
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When concentrated HCI is added to a pink solution of cobalt(Il) chloride, the solution
turns blue.
Give an explanation for the observation stated above in terms of the stability constant
of the complex ion formed, and write a balanced equation for the reaction.
Explanation
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Equation
[
(d)
4 marksJ
complete Thble 2 to show the acid/base character of the
oxides of Group IV elements
in the +2 oxidation srate.
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TABLE 2: OXIDES OF GROI p
Group IV Oxides
ELEMENTS
Acid/Base Character
co
(i)
CO,
(ii)
SnO
Pbo
w
Amphoteric
(iii)
[
3 marks]
Total 15 marks
021r2020/cAPE 2010
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8SECTION B
Answer ALL questions.
write your answers in the separate answer booklet provided.
MODI]LE
1
FIINDAMENTALS IN CHEMISTRY
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4.
(a)
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properties of the simple
copy and completeTable 3, which provides information on the
subatomic Particles.
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TABLE3:PRoPERTIESoFSIMPLEStjBAToMICPARTICLES
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(b)
(D
(ii)
4
marks]
field. Name the type of radioRadioactive emissions are affected by an electric
electron. I I' mark ]
actiu" particle that behaves in the same way as the
216
Po decays by emitting
of
216
Po by the emission
the reactant and product
(iii)
from the decay
B particles. State the product formed
BoTH
of three particles and calculate the n/p ratio of
B
[
atoms'
6 marks]
stability of the nucleus of
comment on the effect that the decay has on the
t l mark l
216 po.
84
(c)
(i)
quantum number 2.
Draw the structures of the atomic orbitals of principal
[ 2 marks]
y and z axes in the drawing'
Include x,
(ii)
of ,oCr'
Using s, P, d notation, write the electronic configuration
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Total 15 marks
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o2rl2020lcAPE 2010
-9MODTILE 2
KII\ETICS AND EQTJILIBRIA
5.
A student prepares an ethanoic acid solution of pH 5. He uses this solution to make a buffer.
(a)
Define EACH of the following rerms:
(i)
(ii)
(b)
pH
t 2 marksl
Buffer solution
t
2 marksl
The acid dissociation constant (K.) of ethanoic acid at zs "c has a
numerical value
of I'7 x 10-5- The equilibrium equation for the dissociation of ethanoic acid
is
CH3COOH(aq)
(i)
write
=>
H* (aq) + CHTCOO-(aq).
an expression for the acid dissociation constant
(\)
of ethanoic acid.
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(iD
Calculate the equilibrium concentration of ethanoic acid
in a solution that has
aPHof5.
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(c)
[
4marks]
State the effect, on the equilibrium position
of a buffer solution, of adding small amounts
of
(i)
(ii)
(d)
H.
(aq)
[ I mark ]
oH - (aq).
I t mark ]
A buffer solution is made by adding 20.5 g of sodium
ethanoate (CHTCOONa) to
(K^= 1.7 x l0-s at25 "Cfor ethantic acid).
500 cm3 of 1.5 mol dm-3 ethanoic aciJ.
Calculate the pH of this buffer solution.
(Relative atomic mass: H
: l, C: l2,O :
[
16, Na
:
4 marksJ
23)
Total 15 marks
021r2020/cAPE 2010
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MODI]LE
3
CIIENIISTRY OF THE ELEMENTS
6.
The elements in Period 3 of the periodic table are given below.
NaMgAlSiPSClAr
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(a)
the period Na to
Account for EACH of the following variations in properties across
Ar.
(i)
Electronegativity increases across the period'
[
2 marks]
(ii)
Melting point of the elements increases from Na to Si'
[
2
marks]
(b)
of the elements in Period 3'
Describe the trend in the acid./base character of the oxides
[ 3 marks]
(c)
is acidic. Account for the
When aluminium chloride dissolves in water, its solution
[ 2 marks]
acidic nature of the aluminium chloride solution'
(d)Transitionmetalshavehighermeltingpointsthanmetalssuchascalciuminthes-block
[ 2 marks]
of the periodic table. suigest Two;;asons for this.
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(e)
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poo,o and PCl, are the oxide and chloride of phosphorous
write
an equation to show how
in its highest oxidation state'
EACH of the following reacts with water'
(i)
PnO,o
[
2
(ii)
PCls
[
2marks]
marks]
Total L5 marks
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END OF TEST
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o2rL2020lcAPE 2010