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The Maseno School Mock Committee 2019 Page 1
MASENO SCHOOL
Name …………………………………………………………...Index No. ……………………..
Candidate’s Signature ………………………………… Date: ………………………………..
THE MASENO SCHOOL MOCK EXAMINATIONS
233/2
CHEMISTRY
PAPER 2
JULY 2019
TIME: 2 HOURS
INSTRUCTIONS
a) Write your name and Index Number in the spaces provided above.
b) Sign and write the date of examination in the spaces provided above.
c) Answer all questions in the spaces provided.
d) All working must be clearly shown where necessary.
e) Mathematical tables and silent electronic calculators may be used.
FOR EXAMINER’S USE ONLY
QUESTION MAXIMUM SCORE CANDIDATE’S SCORE
1 12
2 10
3 10
4 13
5 09
6 14
7 12
TOTAL 80
This paper consists of 14 printed pages.
Candidates should check the question paper to ensure that all pages are printed as indicated
And that no questions are missing.
233/2-Chemistry- P2
Thursday 11/07/2019
Time: 11:30am-1:45pm
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QUESTION ONE
The grid below represents part of the periodic table. The letters do not represent the actual
symbols of the elements. Study it and answer the questions that follow.
E T V A
F G J B
W C
a) State and explain the difference in the melting points of F and G. (2mks)
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b) What chemical family name is given to elements T and F. (1mk)
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c) Explain the difference in the nature of aqueous solution of the oxides of F and that of B.
(2mks)
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d) Write an equation for the reaction of W with excess oxygen.(1mk)
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e) How does the electronegativity of A, B and C vary? Explain. (2mks)
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f) Using dots (.) and crosses(x) to represent electrons in the outermost energy level, show
how element V would combine with hydrogen. (1mk)
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g) The compound formed in (f) above can combine with boron trichloride (BCl3) to form an
addition compound. Using dots (.) and crosses to represent electrons show bonding in the
addition compound. (1mk)
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h) Identify the best oxidizing agent from the periodic table. Explain. (2mks)
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QUESTION 2
The diagram below is a flow chart for the extraction of copper. Study it and answer the questions
that follow:
a) Identify the chief ore from which copper metal is extracted. (1mk)
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SO2
Ore Crushed
I
Powdered
Ore
Mixed with water,
oil & air
II
Concentrated
Ore
Copper (I)
Sulphide
Roasted in presence
of sand
IV
Copper (I) Sulphide
and iron (II) Oxide
Liquid
Copper
Cooled
VI
Blister
Copper
Pure
Copper
Electrolysis
VII
Heated in a
converter Slag
Roasted in air
SO2 III
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b) Name process II (1mk)
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c) Give an equation for the reaction that occurs in stage III (1mk)
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d) Explain what happens in stage IV (1mk)
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e) Draw a simple diagram showing the set-up that is used in electrolytic purification of
copper. (3mks)
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f) Name one industry that can be located near a copper extraction plant. (1mk)
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g) Give one use of copper. (1mk)
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h) Brass is an alloy of copper and another metal. Identify the other metal. (1mk)
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i) State one way in which environmental pollution is prevented during the extraction of
copper metal. (1mk)
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QUESTION THREE
5.0g of zinc metal granules were reacted with excess sulphuric(VI) acid. The loss of mass of
contents in the reaction was recorded at various time intervals as shown in the table below.
Time(sec) 0 25 50 75 100 125 150 175
Loss of mass(g) 0 0.55 1.20 1.75 2.25 2.55 2.65 2.65
a) Plot a graph of total loss in mass against time. (3mks)
b) From your graph determine the following;
(i) The total loss in mass after 80 seconds. (1mk)
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(ii) The rate of reaction at the 80th second. (2mks)
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c) Write an equation for the reaction that takes place. (1mk)
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d) Name a catalyst that can be used to speed up the rate of the reaction in this experiment.
(1mk)
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e) Calculate the total volume of hydrogen gas produced at the end of the reaction in cubic
centimeters. (Zn= 65, MGV at r.t.p= 24 litres) (2mks)
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QUESTION FOUR
(a) The atomic number of sulphur is 16. Write the electron configuration of sulphur in
persulphate ion (S2O82- ) (2mks)
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(b) The following are standard electrode potentials for the given half-cells.
34.02
80.0
44.02
13.02
76.02
)(
2
)(
)()(
2
)()(
2
)()(
2
)(
)(
+=→+
+=→+
−=→+
−=→+
−=→+
+
+
−+
−+
−+
s
s
saq
saq
saq
CueCu
AgeAg
FeeFe
PbePb
ZneZn
VoltsE
aq
aq
i) Which one of the above is the
Strongest reducing agent? (1 mk)
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Strongest oxidizing agent? ( 1 mk)
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ii) What would be observed when a zinc rod is dipped into a solution containing copper II
ions? Explain using E values. (2mks)
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(c) The set-up below was used during the electrolysis of Magnesium Sulphate solution using
graphite electrons. Gas Y Gas X
(i) Which electrode is the cathode. (1mk)
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(ii) Write the half ionic equation for the reaction that takes place at the anode. (1mk)
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(iii) Briefly describe a chemical test for gas Y. (2mks)
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(d) An element Q has a relative atomic mass (RAM) of 88. When a current of 0.5 amperes
was passed through the fused chloride of Q for 32 minutes and 10 seconds, 0.44g of Q
were deposited at the cathode. Determine the charge on the ion of Q.
(I Faraday = 96500C) (3mks)
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QUESTION FIVE
The table below shows some tests which were carried out on solutions Q and R and the
observations made. The solutions were divided into two portions each.
Test Observation
a) To the first portion of Q ammonia
solution was added till in excess
White precipitate Q
b) To the second portion of Q, dilute
sulphuric (VI) acid was added.
White precipitate
c) To the first portion of R ammonia
solution was added till in excess
White precipitate R
d) To the second portion of R dilute
sulphuric (VI) acid was added
No white precipitate
a) Identify the possible cations in solution Q and R. (2mks)
Solution Q
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Solution R
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b) State and explain the observations made when a sample of dry white precipitate R is
heated in a test tube. (2mks)
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Study the flow chart below and answer the questions that follow
c) Identify the following. (3mks)
Brown solid B
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Solid A Brown solid B
Solid D Colourless gas E
Black precipitate F
i)Add solid C
ii)Heat
Moist oxygen
Add dilute H2SO4
Bubble through CuSO4 (aq)
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Solid D
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Black precipitate F
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d) Write a chemical equation for the reaction that produces colourless gas E (1mk)
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e) Write an ionic equation for the reaction between gas E and copper(II) sulphate solution.
(1mk)
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QUESTION SIX
a) Draw the functional group represented by each of the following general formulae. R
represents the alkyl part of the compound. (2mks)
(i) R-OH
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(ii) R-COOH
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b) Study the scheme below and answer the questions that follow.
CO2(g) + H2O(l)
CH3CH2COOCH2CH3
water Substance X Substance Y
Substance V Substance Z A + B
CaC2
Step I
1 mole H2
Process I
1 mole H2
Process II
Step II
Process IV
Step III
K(s)
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(i) Name the conditions required for processes I and IV
Process I (1mk)
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Process IV (1mk)
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(ii) Write an equation for the reaction taking place in steps II and III (2mks)
Step II
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Step III
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(iii) Identify substance X and Z (1mk)
X
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Z
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(iv) CH3CH2COOCH2CH3 produced by process IV has a characteristic pleasant
fruity smell. Name the group of compounds to which it belongs. (1mk)
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c) Dichlorodifluoromethane(CCl2F2) is an example of a chlorofluorocarbon-CFC that
was commonly used as a propellant in aerosol sprays.
(i) Draw a dot(.) and cross(x) diagram to show bonding in a molecule of CCl2F2.
(C=6, F=9, Cl=17) (1mk)
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(ii) Nowadays chlorofluorocarbons (CFC’s) have a limited use. Give a reason. (1mk)
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d) Below is a sample of part of a certain polymer.
H H H H
C C C C
C6H5 H C6H5 H n
Given that the molecular mass of a sample of the polymer above is 1040, calculate the
number of monomers in the polymer. (C=12.0 , H=1.0) (1mk)
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e) Pure rubber is soft and sticky. Its physical properties can be improved or modified by the
process shown below.
CH3
CH2 CH2 C CH CH
S
S
CH2 CH2 CH2 CH CH2
n
(i) Name the process that is used to obtain the above product. (1mk)
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(ii) Give two advantages that the above compound has over pure rubber. (1mk)
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(iii) State two uses of the above compound. (1mk)
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QUESTION SEVEN
a) A sample of propan-1-ol (CH3CH2CH2OH) was burnt in a spirit lamp and the heat
evolved used to heat 500cm3 of water in a calorimeter. Study the data below and answer
the question that follows.
Initial temperature of water = 27.0 ℃
Final temperature of water = 46.0 ℃
Initial mass of lamp + propan-1-ol = 50.2g
Final mass of lamp + propan-1-ol = 49.0g
Specific heat capacity of water = 4.2kJkg-1K-1
Determine the molar heat of combustion of propan-1-ol (C= 12 , H= 1 , O= 16) (3mks)
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b) During welding of a fractured railway line by the thermite reaction, a lot of heat energy is
released when aluminium metal reacts with iron(III) oxide in the presence of potassium
chlorate. Use the information below to answer the question that follows.
2Al(s) + 3
2 O2(g) Al2O3(s) ∆Hθ = -1674 kJmol-1
2Fe(s) + 3
2 O2(g) Fe2O3(s) ∆Hθ = -837 kJmol-1
Calculate the enthalpy change for the reaction:
2Al(s) + Fe2O3(s) Al2O3(s) + 2Fe(s) (2mks)
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Study the energy level diagram below and answer the questions that follow.
(i) Determine the following;
Enthalpy change for the reaction. (1mk)
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Activation energy for the reaction (1mk)
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(ii) With a reason, state whether the reaction represented above is endothermic or
exothermic. (1mk)
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c) Study the thermochemical equations below.
C6H12O6(s) + 6O2(g) 6CO2(g) + 6H2O(l) ∆Hθc = -2803.5 kJmol-1
C(s) + O2(g) CO2(g) ∆Hθc = -393.5 kJmol-1
H2(g) + 1
2 O2(g) H2O(l) ∆Hθ
c = -286kJmol-1
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(i) Draw an energy level diagram linking the enthalpy of formation of glucose,
enthalpy of combustion of carbon, enthalpy of combustion of hydrogen and
enthalpy of combustion of glucose. (2mks)
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(ii) Hence determine the enthalpy of formation of glucose. (2mks)
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