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FORM TP 2017169
rESr coDE 02112020
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MAY/JTINE 2OI7
CARIBBEAN EXAMINATIONS COUNCIL
CARIBBEAN ADVANCED PROFICIENCY EXAMINATION@
CHEMISTRY
UNITl-Paper02
2 hours 30 minutes
READ THE FOLLOWING INSTRUCTIONS CAREF'ULLY.
1
This paper consists of SIX questions in TWO sections. Answer ALL questions
2
Write your answers in the spaces provided in this booklet.
J
Do NOT write in the margins.
4
Where appropriate, ALL WORKING MUST BE SHOWN in this booklet.
5
A data booklet is provided.
6
You may use a silent, non-programmable calculator to answer questions.
7
lf 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.
8.
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 part beside the answer.
DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO
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SO.
Copyright O 2015 Caribbean Examinations Council
All rights reserved.
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0211202003
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-4SECTION A
AnswerALL questions.
MODULB
1
F'UNDAMENTALS IN CHEMISTRY
(a)
l.
Define the term 'relative atomic mass'
[2 marksl
(b)
Dalton's atomic theory suggests that
a
all atoms of a particular element are identical
atoms of elements are indivisible.
State TWO pieces of evidence that lead to the rejection of these claims
[2 marks]
(c)
Write the equation which represents the capture of a neutron by a fluorine-l9 atom with
the resultant expelling of an o-particle.
[2 marksl
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02112020/CAPE2017
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0211202004
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(d)
Figure 1 shows the mass spectrum of the metal zirconium, Zr.
100
Relative
abundance
(%\
51.5
50
tt.2
l7.l
12.6
2.t
88 90 92 94 96 98
mlz
Figure 1. The mass spectrum for zirconiumrZr
Calculate the relative atomic mass of the metal.
[2 marks]
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0211202005
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Ir:
:'-'---1
=
irr
(e)
L, M and N are examples of three solid compounds which are ionic, polar and covalent
t-.'(
:I$
respectively.
Using the format in Table
l, describe
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THREE simple laboratory tests, stating the
L, M and N.
corresponding observations, to show the differences between
.Lr
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TABLE 1: TESTS AND OBSERVATIONS
.-_r!ra
I*
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Observation for Compound
iI\'
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Test
L
M
._t--
:-EI
N
.&
.E
.--t.
_A-Jrl
:-i.-
-:.+
ifti
tg
il$
i-rz+
--ffi
-.tr!
-Li'
.E
.:5i
[7 marksl
Total 15 marks
.{$
.t*i
:.tt
--s
-E
t(
:tr*,
,:rG
..a
:$
!:+l
i-ri+.
iIS
...1*
'---!*
j:€ai-
r-h
i-Ifr
.--t-f
.:E
r'!!iii
-.hT
4!it
---.tr+
-.*
-_t-
---*.'-t*r
-,N
-.\,
&
:.€}
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021t2020lCAPE 2017
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MODULE
2
KINETICS AND EQUILIBRIA
2.
(a)
Define the term 'standard electrode potential'
[2 marks]
(b)
Identify the parts of the standard hydrogen electrode labelled A and B in Figure 2.
A
B
Figure 2. Standard hydrogen electrode
A
B
[2 marks]
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02112020/CAPE 2017
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0211202007
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-8(c)
The electrochemical cell at 298K is represented by the following notation:
Pt(s)lr,(s), r(aq)
(i)
Ii
.l,g+(ao l.lg(s)
Construct a labelled diagram to represent this cell and indicate the direction of
electron flow when the cell is operating.
[4 marks]
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021120201CAPB 2017
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0211202008
flll
llil
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i.-r-:-r
=
=
----
r
i:]:
.j+
-9
(ii)
ff
fr
=i::
-ir.
:aY-_
-
-|
Write the relevant equations to represent the change taking place at the anode and
the cathode.
Anode
.l.la
f!ii::
5t-:
*.:
hi-,
>.:
[1 mark]
.hi:
frf:r
tt+:
E*.
Cathode
fiir
f5--:
ft.
[1 mark]
$,t
A:l
-rr|:
:f{i.l
(iiD
;+
Write the balanced equation for the OVERALL cell reaction.
=
=
'-=t:
[2 marks]
+*r:,
:gr
-xrl-:
(iv)
.-.-.\:
-Ir+-j
:E-:
Refer to the data booklet to calculate the standard cell potential.
-1.+a.'-:
-'Xi.--:
14.
"2E
.Iii:l
rrE:
-!:t-:
[1 mark]
-lEt--:
ItE:
'E-j
:i\1
(d)
.tlt:l
jr*---
List TWO types of energy storage devices.
-')ril-:
.:>--1
_-=a1
rA'l
r'il-:
:-Ar:
:fit-:
:-
[2 marks]
:r:::-:.:::l
i--.=
Total 15 marks
.i.=
.!t+-l
:.f*t
.€l
::=t'l
.-_-_-k
:fai
-_.kl
--Eir
--lCLl
.si-.
._E----1
.€.:
.!5i:
.+itr
:.tt.l
.-Ir+.
,E+-l
:fl-:l
.tl-,Y
.-_*J_:
:ie.
..-s:
JAJ
.t!{-.
GO ON TO THE NEXT PAGE
'.-l-r:+
..--:-r
.'....---.:
=
.,r_...."......:
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02112020/CAPE 2017
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0211202009
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-10MODULE 3
CHEMISTRY OF THE ELEMENTS
KCIO3 undergoes disproportionation when heated to just above its melting point to produce KCI
and KClOo.
3.
(a)
(i)
Define the term 'disproportionation'
[1 markl
(ii)
Write the balanced equation for the reaction above and hence deduce the oxidation
number of chlorine in KCIO, and KCIO. respectively.
[3 marksl
(b)
Explain the trend in volatility of the halogens as the group is descended.
[3 marksl
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0211202010
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(c)
MX
is the formula of a salt of the halogen with a relative atomic mass
was asked to carry out the following tests on MX.
of 80. A student
Complete Table 2 to show the student's record of the observations made.
TABLE 2: RECORD OF OBSERVATIONS
No.
Observation
Test
(D Warm with concentrated HrSOo
[2 marks]
(ii)
Add AgNO,(ag) to MX(aq) followed by
concentrated NHr(al).
[2 marks]
( lll ) Pass Clr(B) through MX(aq).
[l markl
(d)
Write an ionic equation to show the oxidizing nature of sulfuric acid in Test (c) (i).
[3 marksl
Total 15 marks
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0211202011
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-12SECTION B
AnswerALL questions.
MODULE
1
FUNDAMENTALS IN CHEMISTRY
4.
(a)
Apply the concept of the 'hybridization of atomic orbitals'to explain the planarity of the
ethene molecule.
[3 marks]
(b)
(i)
State TWO principles which form the basis
repulsion (VSEPR) theory.
of the valence-shell electron pair
[2 marks]
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02tt2020lCAPE2017
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0211202012
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(ii)
Use the VSEPRtheory to account for the difference in shape between the ammonia
molecule (NH3) and the ammonium ion Q.{Ho*).
Ammonia molecule (NHr):
Ammonium ion (NHu"):
[4 marksl
(c)
A solution of potassium iodide was made by dissolving20 g in I dm3 of water. A mixture
of 25 cm3 of this solution and an equal volume of dilute sulfuric acid on titration with
0.02 mol dmi potassium dichromate(Vl) solution needed 24.80 cm3 for complete oxidation.
Calculate the molar ratio of CrrOr2- to I- and hence derive the ionic equation for the reaction
which has occurred.
Molar ratio:
Ionic equation
[6 marksl
Total lS marks
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02t12020lcAPE 2017
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0211202013
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-14MODULE
2
I(NETICS AND EQUILIBRIA
s.
(a)
Explain EACH of the following terms:
(i)
Rate law
[2 marksl
(ii)
Order of reaction
[2 marks]
(b)
Parts (b) (i) to (b)
(iii) refer to the following reaction.
aX + bY
(i)
Products
Write an expression
--=-> for the rate law.
[2 marks]
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02t12020tcAPE 2017
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0211202014
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(ii)
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15 -
Write an expression for the OVERALL order of reaction
[1 markl
(iii)
The overall order of this reaction was found to follow second-order kinetics
Deduce the units of the rate constant for the reaction.
I
(c)
mark]
The decomposition of gaseous nitrogen(V) oxide exhibits first-order kinetics and is
represented by the equation
4NOr(g)
2N2Os(g)
+
Or(S)
A proposed mechanism for the reaction is made up of the following steps (W and Z arc
intermediates):
NrO,
w
=L-
w *oa
z +No2
30, + Nrg,
z + 2N2Os
Use the information relating to the kinetics of the reaction to write the equation representing
the rate determining step. Give a reason for your response.
Equation:
Reason:
[3 marks]
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02tt2020lCAPE 2017
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0211202015
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Data for the decomposition of nitrogen(V) oxide at 333 K is presented in Table 3
TABLE 3: DATA FOR THE
DECOMPOSITION OF
NTTROGEN(V) OXrDE
Pressure
of
Nitrogen(V) Oxide
Remaining (Pa)
(i)
Rate of Reaction
(Pa per second)
960
0.83
800
0.70
640
0.55
320
0.27
Plot the data on the grid provided on page 17, circling the plotted points
8.
[2 marks]
(ii)
Using the graph in (d) (i), calculate the rate constant for the decomposition of
nitrogen(V) oxide at 333 K, stating the appropriate units.
[2 marks]
Total 15 marks
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02tt2020lCAPE 2017
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0211202016
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._:'-t
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=
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-\---.
.+.
gr.-r+r
2i:
ltt:
!*-:
:!:
*:
:+l
*I,
l+-l
=-'
!*--
-l
f,---.
>.:
s-.
-r---
i}l
-
__l-:
..+
-t-t---r
=
ir.
=
!r1-
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18 -
MODULB 3
CHEMISTRY OF THE ELEMENTS
6.
Table 4 provides information on the atomic radius (AR), ionization energy (lE) and standard
electrode potential (E') for some metals.
TABLE 4: INFORMATION ON THE ATOMIC RADIUS (AR),
IONIZATION ENERGY (IE) AND STANDARD ELECTRODE POTENTIAL
FOR SOME METALS
(a)
Metal
AR (nm)
IE (kJ mol-l)
Beryllium
0.t22
1760
-1.85
Magnesium
0.160
1
450
1.37
Calcium
0.197
It50
-2.87
Strontium
0.21s
I
060
-2.89
Barium
0.225
966
-2.91
Eo
(EO)
(v)
Explain, using relevant data from Thble 4, the trends in the atomic radius and ionization
energy of the metals.
[3 marksl
(b)
(i)
Describe the difference in the reactions of calcium and barium with water.
[1 mark]
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02n2020/cAPE 2017
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0211202018
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(iD
Using the data from Table 4, explain the differences described in (b) (i).
[2 marks]
(c)
(i)
Describe the difference in the reactions of the chlorides of elements Na, Mg and
water.
Alwith
[2 marksl
=,
(ii)
With reference to the ionic radius and electropositivity of the elements, explain
the differences in (c) (i) and deduce the type of bonding present in the chlorides.
Differences
Type ofbonding
[5 marks]
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02n2020/cAPE 2017
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0211202019
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(d)
(i)
-l
-
State how calcium oxide is used in agriculture
i ma rk
(ii)
Write an ionic equation to represent the process involved in the use stated in
(d) (i).
[1 mark]
Total 15 marks
END OF TEST
IF YOU FINISH BEFORE TIME IS CALLED, CHECK YOUR WORK ON TIIIS TEST.
02t12020lcAPE2017
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