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1.
The table above shows pH values of 25 cm3 ethanoic acid solutions of different concentrations
measured by a student using a pH meter
(a) State the variables of this experiment.
[3 mark3]
(b) Suggest a hypothesis of the experiment.
[2 marks]
(c) Plot a graph of pH value against concentration of ethanoic acid solutions.
[3 marks]
(d) From your graph determine
the concentration of the hydrochloric acid solution with pH value of 3.8
[1 mark]the pH value of the hydrochloric acid of concentration 0.22 mol dm -3.
[1 mark]
( L=3 )
Written Practical Test
Instruction:Answerallquestions.
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2.
Hydrogen peroxide decomposes in the presence of manganese(IV) oxide catalyst to form water
and oxygen gas :
2H2O2(l) 2H2O(l) + O2(g)
The table above shows the result obtained by a student.
(a) Define a catalyst.
[3 mark3]
(b) State the variables of this experiment.
[3 marks]
(c) Suggest a hypothesis of the experiment.
[2 marks]
(d) Suggest how you collect the oxygen gas.
[2 marks]
(e) If the experiment is repeated by replacing the manganese(IV) oxide with chromium(III)oxide, the results obtained are shown in the table below:
What can observe from the results tabulated above?
[1 mark]
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What can you conclude from this result?
[1 mark]
( L=3 )
3. A salt solution conducts electricity whereas an organic solvent does not.
Using aqueous sodium chloride solution and hexane solution, describe an experiment to provethe above statement. Your answer should include:
(a) Problem statement
[3 marks]
(b) A hypothesis for the experiment.
[3 marks]
(c) State all variables of the experiment.
[3 marks]
(d) List down the apparatus and chemicals needed to carry out the experiment.
[3 marks]
(e) Write the procedures taken to carry out the experiment.
[3 marks]
(f) Tabulate your result.
[3 marks]
( L=3 )
4. The table below shows the result obtained when molten naphthalene is cooled from 90oC.
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(a) Draw a labeled diagram of the apparatus used to carry out the experiment.
[3 marks]
(b) Plot a graph of temperature against time from the results shown above.
[3 marks]
(c) State the melting point of naphthalene.
[1 mark]
(d) What is the physical state of naphthalene at time 3 minutes?
[2 marks]
(e) Explain why the temperature between the time 2 minute to 4 21
minute remains constant?
[3 marks]
(f) The melting point of naphthol is 65oC. If a molten mixture of naphthol and naphthalene is
cooled, sketch the graph of temperature against time obtained.
[3 marks]
( L=3 )
5. Three experiments are carried out as shown by the diagrams below.
(a) What is the aim of the experiments?
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[3 marks]
(b) State the hypothesis of the experiment.
[3 marks]
(c) State the following variables of the experiments.
manipulated variable
[1 mark]
responding variable
[1 mark]constant variable
[1 mark]
(d) Tabulate your results.
[6 marks]
(e) Name the process taking place in each of the experiment above.
[1 mark]
( L=3 )
6. With the presence of impurities the melting point of a substance is lowered
Describe an experiment to prove the above statement. Your answer should include the following
items:
(a) Aim of experiment .[3 marks](b) All variables involved.[3 marks]
(c) List of apparatus and chemicals used.[3 marks]
(d) Procedure of experiment.[3 marks](e) Tabulation of result.[3 marks]
(f) Discussion of result.[3 marks]
( L=3 )
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7.
The diagrams above show the procedure taken when carrying out an experiment to determinethe empirical formula of magnesium oxide.
(a) Write down the procedure taken when carrying out the experiment in the spaces provided.[5 marks]
(b) Why must the magnesium ribbon cleaned with sand paper?
[1 mark]
(c) After opening the lid (step iv), it must be closed back immediately.
Explain why.
[2 marks]
(d) Determine the empirical formula of magnesium oxide.(O=16, Mg=24)
[3 marks]
( L=3 )
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8.
Hydrated copper(II) sulphate crystals can be represented by the formula CuSO4.xH2O, where xis the number of moles of water of crystallisation in the hydrated copper(II) sulphate.
When heated, the hydrated copper(II) sulphate salt releases its water of crystallization leaving
behind the anhydrous copper(II) sulphate :
CuSO4.xH2O(s) heating
CuSO4(s) + xH2O(g)
Hydrated copper(II) sulphate Anhydrous copper(II) sulphate
An experiment is carried out to determine the number of moles of water of crystallization , x , in
the copper(II) sulphate crystals.
The steps of the experiment are described above.
(a) State the change in colour when hydrated copper(II) sulphate is heated.
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[1 mark]
(b) Why the heating, cooling and weighing process must be repeated until a constant mass is
obtained?
[2 marks]
(c) Calculate the mass of anhydrous copper(II) sulphate obtained. How many moles is this?
[3 marks]
(d) Calculate the mass of water of crystallization removed. How many mole is this?
[3 marks]
(e) Determine the value of x that is the number of moles of water of crystallization in the
copper(II) sulphate crystals.Write the formula of copper(II) sulphate crystals.
[3 marks]
(f) State one use of anhydrous copper(II) sulphate obtained in this experiment.
[2 marks]
( L=3 )
9. Metal X is a transition element and it is below hydrogen in the reactivity series. Metal X form
two metal oxides with the formula XO and X2O. You are provided a sample of metal X oxide
and are required to determine the empirical formula of the oxide. Your answer should includethe following:
(a) Aim of the experiment
(b) Hypothesis
(c) List of apparatus and chemicals used.(d) Procedure of the experiment.
(e) Tabulation of the results.
(f) Calculation to show how the empirical formula is determined.(Relative atomic mass of O=16, X=64)
[18 marks]
( L=3 )
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10. An experiment was carried out to study the property of oxides of elements in Period 3 in the
Periodic Table. 2 cm3 of dilute nitric acid and sodium hydroxide was poured into two separate
test tubes. Magnesium oxide was added to each of the solution and stirred with a glass rod. Thesolubility of the magnesium oxide was recorded. The experiment was repeated by replacing the
magnesium oxide with:
(a) aluminium oxide, Al2O3(b) phosphorus pentoxide, P4O10The results were tabulated below:
(a) State the aim of this experiment.
[2 marks]
(b) State the following variables of the experiment.
manipulated variable
[1 mark]responding variable
[1 mark]
controlled variable
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[1 mark]
(c) Write a balanced equation for the reaction between nitric acid and magnesium oxide.
[2 marks]
(d) What conclusion can you make from the results of the experiment?
[3 marks]
( L=3 )
11. An experiment is carried out to determine the reactivity of chlorine, bromine and iodine.
Chlorine gas was passed over heated iron wool. The reactivity of the reaction was noted. The
experiment was repeated by passing bromine gas and iodine vapour over heated iron wool. The
results of the experiments were tabulated below:
(a) Arrange the reactivity of the halogens in order of increasing reactivity.
[2 marks]
(b) Explain why the reactivity shows this order.
[6 marks]
Name the brown solid formed between iron wool and chlorine.
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[1 mark]Write a chemical equation for the reaction between iron wool and chlorine gas.
[3 marks]
What is the function of the sodium hydroxide solution?
[1 mark]
Write a chemical equation involving the sodium hydroxide.
[2 marks]
( L=3 )
12. Lithium, sodium and potassium are in Group 1 of the Periodic Table.
Describe an experiment to prove that the reactivity increases down the Group from lithium to
potassium. Your explanation should include the following:
(a) Aim of experiment [1 mark](b) State of hypothesis [2 marks]
(c) List of chemicals and apparatus [3 marks]
(d) List of all the variables. [3 marks](e) Procedures of experiment. [6 marks]
(f) Tabulation of data. [5 marks]
( L=3 )
13. An experiment is carried out to determine the solubility of potassium iodide and naphthalene.
2 cm3 of solvent X and solvent Y are poured into two separate test tubes. 2 g of solidnaphthalene are added to each test-tube. The mixture was stirred with a glass rod. The solubility
of the two substances is recorded. The experiment is repeated by replacing the naphthalene with
sodium chloride. The results are shown below:
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(a) Suggest what is solvent
X
[1 mark]
Y
[1 mark]
(b) State one use of
naphthalene
[1 mark]
potassium iodide
[1 mark]
(c) If potassium iodide is mixed with naphthalene by mistake, describe how you can separate
the two mixtures.
[6 marks]
( L=3 )
14.
The empirical formula of magnesium oxide is determined by heating magnesium metal in air. A
20 cm long magnesium ribbon is cleaned with sand paper. An empty crucible with its lid is
weighed. The magnesium ribbon is the placed in the crucible and the crucible with its content isweighed again. The crucible is then heated strongly until the magnesium ribbon starts to burn.
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The lid of the crucible is opened and closed occasionally during the combustion of magnesium.
After the combustion the crucible and its contents are cooled and weighed again. The results are
tabulated below:
(a) State the colour of the magnesium oxide formed.
[1 mark]
(b) State one use of magnesium oxide.
[1 mark]
(c) From the data above, calculate the empirical formula of magnesium oxide.
(O=16, Mg=24)
[3 marks]
(d) Using electronic configuration, explain how the magnesium oxide compound is formed.
[5 marks]
( L=3 )
15. Covalent compound is a non electrolyte whereas an ionic compound is
Describe an experiment to prove the above statement. Your answer should include the
following:
(a) Aim
(b) Hypothesis(c) State all variables involved.
(d) Apparatus and chemicals used(e) Procedure of experiment(f) Tabulation of result.
[18 marks]
( L=3 )
16. A student carried out an experiment to electroplate a key with copper metal. He set up the
apparatus as shown below:
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He failed to obtain the desired results.
(a) State two mistakes he made.
[2 marks]
(b) He corrected the mistake. Draw a labeled diagram for the new sep-up.
[2 marks]
(c) Write half ionic equation for the reaction occurring at the
anode
[1 mark]cathode
[1 mark]
(d) State the reaction taking place at each electrode.
[2 marks]
(e) State the direction of movement of the electrons.
[1 mark]
( L=3 )
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17.
(a) In experiment I, name the products formed at(i) anode
(ii) cathode
[1 mark]What factor determines the types of ions discharged at the electrodes?
[1 mark]
Name the greenish gas formed at the anode in experiment II.
[1 mark]
Write half ionic equation for the formation of this gas.
[1 mark]
If the electrolysis proceeds longer, another colourless gas evolve at the anode. Namethe gas. Explain how this gas is formed.
[2 marks]
Name the brown deposit formed at the cathode in experiment II.
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[1 mark]
Write half ionic equation to show how this deposit is formed.
[1 mark]
Name the brown solution X formed at anode in experiment III.
[1 mark]Suggest a test to identify the product in (c) (i) above.
[1 mark]
( L=3 )
18. You are given four metals P, Q, R, S and its salt solutions P nitrate, Q nitrate, R nitrate and S
nitrate. Describe an experiment to prove that the electro-positivity of the metals decreases in
the order R, P, S, Q. Your answer should include the following:
(a) Aim of experiment.
[3 marks(b) Hypothesis of experiment
[3 marks
(c) List of apparatus and chemicals.[3 marks
(d) Procedure of experiment.
[3 marks
(e) Tabulation of results.[3 marks
(f) Discussion of the results obtained
[3 marks
( L=3 )
19.
The table above shows pH values of 25 cm3 hydrochloric acid solutions of differentconcentrations measured by a student using a pH meter
(a) State the variables of this experiment.
[3 marks]
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(b) Suggest a hypothesis of the experiment.
[2 marks]
(c) Plot a graph of pH value against concentration of ethanoic acid solutions.
[3 marks]
(d) From your graph determine
the concentration of the hydrochloric acid solution with pH value of 1.5
[1 mark]
the pH value of the hydrochloric acid of concentration 0.05 mol dm-3
.
[1 mark]
( L=3 )
20.
A student carried out an experiment to prepare 250 cm 3 of a standard potassium hydroxide
solution as shown in the diagram above. The KOH is then dissolved in about 100 cm3
of distillwater. The mixture is stirred with a glass rod until the potassium hydroxide dissolved. The
solution is then poured into the volumetric flask. The beaker and the glass rod is rinsed withdistill water and each rinsing is poured into the volumetric flask. Distill water is added until the
250 ml mark. The mixture is then shaken to get a homogeneous solution.
(a) Calculate the mass of potassium hydroxide weighed.
How many moles is this?
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(H=1, O=16, K=39)
[3 marks]
(b) Why must the beaker and glass rod be rinsed with distill water and each rinsing poured intothe volumetric flask?
[1 mark]
(c) Explain the meaning of homogeneous solution.
[1 mark]
(d) Calculate the concentration of the solution prepared in mol dm-3
.
[2 marks]
(e) 25.0 cm3 of this KOH solution neutralize 10 cm3 of sulphuric acid solution. Determine theconcentration of the sulphuric acid solution in mol dm-3.
[3 marks]
( L=3 )
21. You are required to determine titration to determine the concentration of a hydrochloric acid of
concentration of approximately 1 mol dm-3. Describe an experiment to carry out the task. Your
answer should include the following:
(a) Aim of experiment.
[3 marks(b) List of apparatus and chemicals.
[3 marks
(c) Procedure of experiment.
[6 marks
(d) Tabulation of results.
[3 marks(e) Show all the calculation steps.
[5 marks
( L=3 )
22. (a) The table involves qualitative analysis of an unknown solution labeled BA 1. The
observation is recorded in the table below. Write the inference for each observation. Then
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identify the cation and anion present in BA 1.
The cation present in BA 1 is The anion present in BA 1 is
[9 marks]
(b) BA 2 is a black powder. Test is carried on BA 2 and the observations are recorded in the
table below. Write inference for each observation.
BA 2 is .
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[9 marks]
( L=3 )
23. (a) A student carried out analysis on solid BA 3 and tabulated his result below.
Write down the inference for his observations in the spaces provided.
BA 3 is ..
[9 marks]
(b) A student was provided with solid copper(II) carbonate which is labelled BA 4.
(i) Write down the observations expected when reactions are carried on this compound.
(ii) Write equations for reactions in (a), (b) and (c) above.
[9 marks]
( L=3 )
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24. You are provided with 100 cm3 of 0.1 mol dm-3 sodium hydroxide solution. You are required
to show that the higher the concentration of the sodium hydroxide solution, the higher is its pH
value. Your answer should include the following:
(a) Problem statement
(b) Hypothesis(c) Variables of experiment
(d) Apparatus and chemical
(e) Procedure of experiment.(e) Tabulation of result.
[18 marks
( L=3 )
25.
The diagram above shows the structure of two materials.
(a) Name the material
P
[1 mark]
Q
[1 mark]
(b) Which of the material is stronger?
[1 mark]
(c) Explain your answer to (b) above.
[3 marks]
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(d) State one use of the material Q.
[1 mark]
( L=3 )
26. Below are structures of some molecules, some of which can form polymers.
(a) Define the term polymer.
[2 marks]
(b) There are two types of polymers. Which of the molecules above can form
addition polymers
[2 marks]
condensation polymers
[2 marks]
Which one of the molecules above cannot form polymer?
[1 mark]
Explain your answer.
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[1 mark]
(d) Draw the structure of the polymers form between Q and R.
[2 marks]
( L=3 )
27. An alloy is harder than its pure metal from which it is derivedDescribe an experiment to prove the above statement.
(a) Problem statement(b) Hypothesis
(c) Variables of experiment
(d) Apparatus and chemical
(e) Procedure of experiment.(e) Tabulation of result.
[18 marks
( L=3 )
