Name……………………………………………
Index No………………/…….
School…………………………………………
Candidates Signature……….
Date…………………………..
233/2
CHEMISTRY
Paper 2
(THEORY)
July/August 2015
TIME 2 HOURS
NAKURU DISTRICT SEC. SCHOOLS TRIAL
EXAMINATIONS - 2015
Kenya Certificate of Secondary Education (K.C.S.E)
233/2
CHEMISTRY
Paper 2
(THEORY)
July/August 2015
TIME: 2 HOURS
INSTRUCTIONS TO CANDIDATES
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Write your name and Index Number in the spaces provided above.
Sign and write date of examination in the spaces provided above.
Answer ALL questions in the spaces provided.
Mathematical tables and electronic calculators may be used.
All workings MUST be clearly shown where necessary.
Questions
1
2
3
4
5
6
7
TOTAL
Maximum Score
10
12
12
11
13
10
12
80
Candidate’s Score
This paper consists of 10 printed pages
Candidates should check the question paper to ensure that all the
Papers are printed as indicated and no questions are missing
Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 1
1. The diagram below shows a set-up to determine the heat of combustion of propanal. The heat
produced by burning fuel heats a known mass of water. By measuring the temperature rise of water
it’s possible to approximate the value for the heat of combustion of propanol
Volume of water = 400cm3
Initial temp. of water = 20oC
Final temp. of water = 33oC
Mass of propanol burnt = 0.6 g
Specific heat capacity of water = 4.2j g-1k-1
(a) Define molar heat of combustion
(1 mark)
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(b) Calculate the number of moles of propanol that burnt (C=12, H=1, O=16)
(2marks)
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(c) Calculate the enthalpy change in this experiment
(3 marks)
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Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 2
(d) Find the molar heat of combustion of propanol
(2 marks)
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(e) The accurate value of molar heat of combustion of propanol is -2021kj/mol. State Two errors
that could account for this difference
(2 marks)
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(f) When choosing a fuel what is considered
(1 mark)
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2. The table below shows selected elements from the periodic table, the letters do not represent the
actual chemical symbols. Study it and answer the questions that follows:
Element
A
B
C
D
Atomic number
15
11
17
10
Boiling point (oC)
280
890
-34
-245
(a) Choose an element that is the most reactive non-metal. Give a reason
(2 marks)
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(b) Which element does not form ions? Explain
(2 marks)
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Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 3
(c) Give the formula of the oxide of B and state its nature
(2 marks)
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(d) Element C has which type of structure, give a reason for your answer
(2 marks)
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(e) Write the equation for the reaction of element A and oxygen
(1 mark)
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(f) Element C atom has a mass number of 35. How many neutrons does it have
(1 mark)
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3. The compounds below are hydrocarbons
J – CH3(CH2)4 CH3
T – CH3 C(CH3)2 CH2CH3
R- CH3 CH2 CH3
(a) Give their systematic names
(3 marks)
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b) Two of the three compounds are Isomers?
(i) What is an isomer?
(1 mark)
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Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 4
(ii) Identify the two isomers
(1 Mark)
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(c) The flow chart shows some reactions or organic compounds. Use it to answer the questions that
follows:
Y
HCL
polypropene
Step 1
Propene
H2
W
High temp.
Con. H2SO4 at 180oC
Ethanoic acid
X
Z
Con. H2So4
(i)Name the products
(4 marks)
X……………………………………………………………………………………………….
Y………………………………………………………………………………………………
W…………………………………………………. ………………………………………….
Z ………………………………………………………………………………………………
(ii) Give the conditions necessary for step 1 to take place
(2 marks)
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(iii) Name the reaction that converts X to Z
(1 mark)
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Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 5
4. The set-up below was used to prepare Oxygen gas
(a) Give the name of substance M ……………………………………………………………(1 mark)
(b) Write the equation for the above reaction
(1 mark)
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(c )Name the method of collection of oxygen above and what property of oxygen make it to be
collected that way.
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(d) Explain the following observation when burning magnesium is lowered into a gas jar of
carbon(IV) oxide it continues to burn, but when burning zinc is lowered in a gas jar of carbon(IV)
oxide it does not burn.
(2 marks)
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(e) Give an equation for reaction between burning magnesium and carbon (IV) oxide
(1 mark)
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(f) Two major car exhaust gases are carbon (II) oxide and Nitrogen (II) oxide. Explain how each is
formed .
(3 marks)
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Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 6
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(g) List 2 commercial uses of Oxygen gas
(2 marks)
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5. When dry Ammonia gas is passed over heated copper(II) oxide in a combustion tube two products
are obtained apart from the copper metal
(a) Write an equation for the above reaction
( 1 mark)
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(b) State the observations made in the combustion tube
(2 m arks)
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(c) If 480cm3 of ammonia gas reacted completely with the copper (II) oxide. Calculate
(i) The mass of water formed.
(Molar gas volume at r.t.p=24 litres)
(3 marks)
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(ii) Mass of copper (II) oxide that reacted. (N=14, Cu =63.5, H=1, O=16, molar gas volume is 24
litres at r.t.p)
(2 marks)
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(d) During fractional distillation of liquid air, state how water is removed
(2 marks)
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Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 7
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6. The flow chart below shows the stages in the industrial manufacture of sodium carbonate. Study it
and answer the questions that follow.
Water
Ca (OH) 2
CO2
step 4
G
Limestone
step 3
K
L
Brine
step 1
1
Water
L and
NaHCo3
NaHCo3
me
CO2
step 2
Water
me
Na2co3
(a) Name K…………………………………. ………………………………………………..
L……………………………………………………………………………………..
G…………………………………… ………….....................................................(3 marks)
(b) What is the name given to industrial manufacture of sodium carbonate
(1 mark)
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(c) Write the equations of reaction taking place in step I
(2 marks)
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(d) How is step 2 achieved
(1 mark)
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Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 8
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(e) State how the products in step 1 are separated
(2 marks)
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(f) This process is said to be very efficient. Explain this
(2 marks)
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(g) Using dots and crosses show how the bonding of carbon (IV) oxide is achieved
(atomic numbers C- 6, O-8)
(2 marks)
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7. This is the extraction of copper. Study it and answer the questions that follow:
Gas R
Air
Powdered
ore
I
Ore concentration
II
Slag Y
Cu2S and
FeO
III
Liquid
copper
IV
Copper (I)
sulphide
Gas S
(a) Step 1 is called froth floatation, briefly describe it
(3 marks)
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(b) Name Gas R……………………………………………………………………………….
Gas S……………………………………………………………………………….
Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 9
Slag Y………………………………………………………………………….
(3 marks)
(c) Write an equation for formation of liquid copper in step (IV)
(1 mark)
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(d)(i) On the space provided below draw a well labelled diagram to show the electrolysis of copper
(II) sulphate solution using copper electrodes
(3 marks)
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(ii) As the electrolysis proceeds, explain the observation made at each electrode
(2 marks)
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Nakuru District Sec. Schools Trial Examination @ 2015 Chemistry paper 2
Page 10