Chemistry pp1 qts
1. (a) The grid given below represents part of the periodic table study it and answer the que
that
follow. (The letters do not represent the actual symbols of the elements.)
A
B
C
D
E
F
stions
(i) What name is given to the group of elements to which C and F belong?
(1 Mark)
(ii) Which letter represents the element that is least reactive?
(1 Mark)
(iii) What type of bond is formed when B and E react? Explain
(2 Marks)
(iv) Write formula of the compound formed where elements D and oxygen gas react.
(1 Mark)
(b) Study the information in the table below and answer the questions that follow. (The letter do no
represents the actual symbols of the substance.
Substance
Melting point 0C
Boiling point 0C
Solubility in water Density at room
temp/g/cm3
H
-117
78.5
Very soluble
0.8
J
-78
-33
Very soluble
0.77 x 1-3
K
-23
77
Insoluble
1.6
K
-219
-183
Slightly soluble
1.33 x 10-3
I. (i) Which substance would dissolve in water and would be separated from the solution by fractional
distillation.
(1 Mark)
(ii) Which substances is a liquid at room temperature and when mixed with water two layers would
be formed?
(1 Mark)
II. Which letter represents a substance that is a gas at room temperature and which can be collected by.
(i) Over water?
(1 Mark)
(ii) By downward displacement of air? Density of air at room temperature = 1.29 x 10-3 g/C
(1 Mark)
2. Study the flow chart below and answer the questions that follow.
(a) Identify
(i) Gas F
(ii) Liquid H
(iii) Solid P
(b) State one use of calcium chloride.
(c) Give two reasons why such a plant should be cited near a river.
(d) Write equations for the reactions occurring in chamber:
(i) N
(ii) S
(e) Using an ionic equation, explain how sodium carbonate is used to soften hard water.
(f) Explain how ammoniacal brine is formed.
(g) State one use of sodium hydrogen carbonate.
Mwingi Central District Joint Examination
(1Mark)
(2 Marks)
(2 Marks)
(1 Mark)
(1 Mark)
(1 Mark)
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Chemistry pp1 qts
3. Use the information in the scheme below to answer the questions that follow.
(a)
(b)
(c)
(d)
Name substance P
(1 Mark)
Give the structure and name of compound Q.
(1 Mark)
Write the equation for the chemical reaction in steps III
(1 Mark)
Name the reagents and conditions necessary for the reaction in
(i) Step IV
(1 Mark)
Reagents
(1 Mark)
(ii) Step VII
Reagents
(1 Mark)
Conditions
(1 Mark)
(e) What name is given to the reaction in step VII?
(1 Mark)
(f) Below are two reactions showing how a long chained alkanoic acid can be converted into detegernt
B.
I.
II.
(i) Name the type of reaction in I and II
(2 Marks
4. In an experiment to determine the heat of combustion of Methanol, CH3OH, a student used a set-up like
the one shown in the diagram below. Study the set-up and the data below it and answer the questions that
follow.
Volume of water
=
500cm3
Final temperature
=
27.00C
Initial temperature of water
=
20.00C
Final mass of lamp + Methanol =
22.11g
Initial mass of lamp + Methanol =
22.98g
Density of water
=
1.0gcm-1
1
(Specific heat capacity = 4.2Jg 0C )
(a) Calculate
(i) The number of moles of Methanol used in the experiment.
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(1 Mark)
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Chemistry pp1 qts
(C = 12, O = 16, H = 1)
(ii) The heat change in this experiment.
(1 Mark)
(iii) The heat of combustion per mole of Methanol.
(2 Marks)
(b) Explain why the value of the molar heat of combustion of Methanol obtained in this experiment is
different from the theoretical value.
(2 Marks)
(c) On the axis below draw an energy level diagram for the combustion of the Methanol.
(2 Marks)
(d) The table below gives factors which affect the rate of the reaction between Zinc and Hydrochloric
acid.
(i) Complete the table to show how the factors given affect the rate of reaction between Zinc and
Hydrochloric acid.
(2 Marks)
Factor
Effect on the rate of reaction Explanation
Using Zinc powder instead
of Zinc granules
Heating the reactants
(ii) Name the catalyst that will be added to increase the rate of reaction.
(1 Mark)
(iii) Write an equation between the metal and acid above.
(1 Mark)
5. The following table shows standard electrode potentials for some half reactions
E/Volts
4+
3+
Ce (aq) + e  Ce (aq)
+1.61
3+
Fe (aq) + e Fe2+(aq)
+0.77
I2(aq) + 2e  2I
+0.54
2+
Fe (aq) + 2e  Fe(s)
-0.44
2+
Zn (aq) + 2e-  Zn(s)
-0.76
3+
J +3e + 3e  J(s)
x
Reference to the above table answer the following questions (Base on the values given)
(a) Which is the strongest reducing agent?
(b) Which substance in the table would be used to oxidize iodide to iodine?
(c) Study the cell representation below and answer the questions that follow.
KNO3
2+
Zn(s)/Zn (aq)// Fe2+(aq)/Fe(s)
(i) Identify the anode and the cathode
Anode
(1 Mark)
Cathode
(1 Mark)
(ii) If the two electrodes in (i) above are connected externally, what reactions will take place in each
half cell?
(1 Mark)
(iii) What is the e.m.f of the cell?
(1 Mark)
(iv) What is the role of KNO3?
(1 Mark)
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Chemistry pp1 qts
(v) Write an electrochemical equation to show what happens when a Zinc rod is dipped in a solution
of iron (II) ions.
(1 Mark)
2+
(vi) Explain what happens when KCl is used instead of KNO3 in a case where Pb(s)/Pb (aq) is one of
the half cells.
( 2 Marks)
KNO3
(d) If the e.m.f of the cell J(s)/J (aq) // I2(aq) 2I-(aq) is 1.32V, calculate the value for J3+(aq)/J(s) (The value of
x)
(2 Marks)
6. Study the flow chart below on extraction of copper and answer the questions that follow.
3+
(a) Name the chief copper ore used for the extraction of copper.
(1 Mark)
(b) The amount of copper in the copper ore is usually very small. State the method used to separate the
impurities from the ore in chamber A.
(1 Mark)
(c) (i) What substance is fed into the roaster from chamber A.
(1 Mark)
(ii) Write an equation for the reaction that takes place in the roaster.
(1 Mark)
(d) The copper obtained (blister copper) is not pure. Draw a labelled diagram to show the set-up you
would use to refine the copper by electrolysis.
(2 Marks)
(e) Give two side effects that this process would have on the environment.
(2 Marks)
(f) Bronze is an alloy of copper and another metal.
(i) Name the other metal.
(1 Mark)
(ii) Give one use of bronze.
(1 Mark)
7. The solubility curves of substances X and Y are shown on the grid below. Study the curves and answer
the questions that follow.
(i) State the effects of temperature on solubility of substance Y.
(1 Mark)
0
(ii) Calculate the molarity of substance X in a saturated solution of X at 40 C. (Relative formula mass of
X = 101) Assume density of the solution is 1.0g/cm3)
(2 Marks)
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Chemistry pp1 qts
(iii) At what temperature do the two substances have the same solubility?
(1 Mark)
(iv) Which substance is most likely to be oxygen gas?
(1 Mark)
(v) If a saturated solution of substances X is cooled from 800C to 200C, determine the mass of crystals
that would be obtained.
(2 Marks)
8. The chart below shows some of the chemical needed for the production of ammonia gas, nitric acid and
ammonia sulphate in the industry.
(a) Name the chemical that should be in chambers 1,2,4,8 and 9.
(3 Marks)
(b) State three conditions required to convert the chemical substance in chamber 3 to SO3(g)
(1 ½ Marks)
(c) Write balanced equation with conditions for the reaction that produces the chemical substance in
chamber 7
(2 Marks)
(d) Explain the following with the help of equations. When concentrated sulphuric acid is added to
copper turnings and the mixture heated, a reaction takes place producing a blue solution as one of the
products, when dilute sulphuric acid is added to copper turnings there is no change even after
heating.
( 1½ Marks)
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