Chemistry – Form 3 Secondary – Track 2 – 2016 Page 1 of 12

DIRECTORATE FOR QUALITY AND STANDARDS IN EDUCATION

Department of Curriculum Management

Educational Assessment Unit

Annual Examinations for Secondary Schools 2016

FORM 3 CHEMISTRY TIME: 1h 30min

Name: ________________________________

Class: ________________________________

Useful Data: Atomic numbers and relative atomic masses are shown in the periodic table printed on a separate page.

Marks Grid [ For Examiner’s use only ]

Question

No.

Section A Section B

1 2 3 4 5 6 7 8 9

Max

Mark 10 10 10 10 10 10 20 20 20

Theory

Total

Actual

Mark

Theory Paper: 85% Practical: 15% Final Score: 100%

Track 2

Page 2 of 12 Chemistry – Form 3 Secondary – Track 2 – 2016

SECTION A – Answer ALL questions. This section carries 60 marks.

1 a) State whether the following statements are True or False:

i) Potassium chloride is a base. ______________ [1]

ii) Anhydrous copper(II) sulfate is white. _____________ [1]

b) Give the electron configuration of:

i) S: ______________ [1]

ii) Al3+

: _______________ [1]

c) State which of the following changes are a Physical or a Chemical change:

i) Burning charcoal: _________________ [1]

ii) Melting sulfur: ________________ [1]

d) Write the chemical formula for the following substances:

i) Calcium chloride: ______________ [1]

ii) Magnesium sulfate: _____________ [1]

e) What is the name of the following substances:

i) K2S: ________________________ [1]

ii) Fe(NO3)2: ___________________________ [1]

Chemistry – Form 3 Secondary – Track 2 – 2016 Page 3 of 12

2 The majority of the Earth’s atmosphere is made of two

gases. One is practically inert while the other supports

combustion.

a) What is the name of the gas that is practically inert? How much of this gas does one

find in Earth’s atmosphere?

_____________________________________________________________________ [1]

b) What does the word inert mean?

_____________________________________________________________________ [1]

c) What is the name of the gas that supports combustion? How much of this gas exists

in the atmosphere?

_____________________________________________________________________ [1]

d) Name two other gases that are normally found in clean air.

_____________________________________________________________________ [1]

e) In an experiment to find the percentage amount of oxygen in air, copper turnings are

heated so that they react with the oxygen present in air. The remaining gas would

then be void of oxygen.

i) Draw a labelled diagram to show the apparatus used in this experiment.

[3]

ii) State the colour change of the copper turnings during the experiment.

________________________________________________________________ [1]

iii) Write a balanced chemical equation for the reaction between copper and

oxygen. Do not include state symbols.

________________________________________________________________ [2]

Page 4 of 12 Chemistry – Form 3 Secondary – Track 2 – 2016

3 The picture shows a kitchen tap that is covered with a layer of

deposit due to the hardness found in tap water. This deposit

forms over a long period of time and involves a few chemical

reactions. The process starts when it rains and ends when water

evaporates slowly at the tap.

a) When rain water falls it mixes and reacts with carbon dioxide in the air.

i) What is the name of the substance formed?

________________________________________________________________ [1]

ii) Write a balanced chemical reaction for the reaction between water and carbon

dioxide. Do not include state symbols.

________________________________________________________________ [2]

b) As the acidified rain water is absorbed by the ground, the acidity reacts with the

sedimentary rock which in Malta is mostly made of calcium carbonate. The

substance formed is soluble and is said to make the water hard.

i) What is the name of the soluble substance formed?

________________________________________________________________ [1]

ii) What kind of hardness does this substance produce?

________________________________________________________________ [1]

iii) Write a balanced chemical equation to show the reaction between calcium

carbonate and the acidity in rain. Do not include state symbols.

________________________________________________________________ [2]

c) As we use this hard water through the kitchen tap, some water still remains in the tap

after it is closed which evaporates slowly. Over time, this results in a very slow

reaction that reforms calcium carbonate on the tap as shown in the picture. Write a

balanced chemical equation for this reaction to show how calcium carbonate forms.

Do not include state symbols.

_____________________________________________________________________ [2]

d) How can the calcium carbonate deposit on the kitchen tap be removed by chemical

means?

_____________________________________________________________________

_____________________________________________________________________

[1]

Chemistry – Form 3 Secondary – Track 2 – 2016 Page 5 of 12

4 a) Atoms are the building blocks of matter. They are made of sub-atomic particles

called protons, neutrons and electrons. Fill in the following table on the properties of

these sub-atomic particles.

Mass (a.m.u.) Charge

Protons

Neutrons

Electrons

[3]

b) Sodium fluoride is an ionic compound that is used in toothpaste. It consists of two

elements, sodium and fluorine. In nature, fluorine is found as diatomic molecules that

are covalently bonded. In the box below, draw a dot cross diagram showing all

electron shells, of a molecule of fluorine.

[2]

c) State, in terms of electrons, what happens when sodium reacts with fluorine to

produce sodium fluoride.

_____________________________________________________________________ [1]

d) Draw a dot cross diagram, showing outer electron shells only, to show the bonding in

sodium fluoride.

[2]

e) Chlorine has two isotopes, Cl1735 and Cl17

37 . They exist in the ratio of 3:1 respectively.

Calculate the relative atomic mass of chlorine.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

[2]

Page 6 of 12 Chemistry – Form 3 Secondary – Track 2 – 2016

5 Acids are a group of compounds that have similar chemical

properties.

a) Name two properties of acids.

_____________________________________________________________________ [1]

b) What is the range of pH that acids would give when they are dissolved in water?

_____________________________________________________________________ [1]

c) What is the difference between a strong and a weak acid?

_____________________________________________________________________

_____________________________________________________________________

[1]

d) Hydrochloric acid is a strong mineral acid that reacts with many substances. Name or

write formulae of all the substances that will be produced when HCl reacts with:

i) Sodium hydroxide, NaOH

________________________________________________________________ [1]

ii) Copper oxide, CuO

________________________________________________________________ [1]

iii) Magnesium, Mg

________________________________________________________________ [1]

iv) Lithium carbonate, LiCO3

________________________________________________________________ [1]

e) When the kitchen drain becomes clogged with grease, water

cannot flow through it properly. Sodium hydroxide can be

bought from the hardware store to unclog it. This product comes

in concentrated form so that it can eat away at the grease and

unclog the blockage easily.

Considering the properties of sodium hydroxide, name two

necessary precautions when handling this material.

_____________________________________________________________________

_____________________________________________________________________

[1]

f) Write a balanced chemical equation for the reaction between sodium hydroxide and

sulfuric acid. Do not include state symbols.

_____________________________________________________________________ [2]

Chemistry – Form 3 Secondary – Track 2 – 2016 Page 7 of 12

6 A student was given a task to calculate the ratio of reacting

particles in magnesium oxide. To do so, the student was

required to burn magnesium ribbon in a crucible as shown in the

diagram.

a) The student used 0.3 g of clean magnesium. Calculate the

number of moles in this amount of magnesium.

_____________________________________________________________________

_____________________________________________________________________

[2]

b) As the crucible was heated, the student lifted the crucible lid slightly. As she was

doing so, the student observed that the magnesium started to glow and so the lid was

put back in place so as not to allow any magnesium oxide smoke to escape the

crucible. This process was repeated until no more glowing was observed and all of

the magnesium reacted.

i) Why was the crucible lid opened repeatedly during the experiment?

________________________________________________________________ [1]

ii) What was happening when the student observed the magnesium glowing?

________________________________________________________________ [1]

iii) Why was it important not to allow smoke to escape the crucible?

________________________________________________________________ [1]

c) When the experiment was over and the student reweighed the contents of the crucible,

the mass had increased by 0.2 g. This was due to the oxygen that reacted with the

magnesium and was equivalent to 0.0125 moles of oxygen. By using your answer in

question a) above, calculate the ratio of reacting particles between magnesium and

oxygen in magnesium oxide.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

[1]

d) Calculate the percentage composition by mass of oxygen in magnesium oxide.

_____________________________________________________________________

_____________________________________________________________________

_____________________________________________________________________

[2]

e) Write a balanced chemical equation for the reaction between magnesium and oxygen.

Do not include state symbols.

_____________________________________________________________________ [2]

Page 8 of 12 Chemistry – Form 3 Secondary – Track 2 – 2016

SECTION B – Answer TWO questions only. This section carries 40 marks.

7 A student was given a mixture of three substances; iodine, copper(II) oxide and sodium

chloride. The following table shows the properties of these three substances.

Substance Solubility in water Action of heat

Iodine, I2 Insoluble Sublimes

Copper(II) oxide, CuO Insoluble Nil

Sodium chloride, NaCl Soluble Nil

a) This student decided to remove sodium chloride from the rest of the mixture.

i) Using water, two beakers, a glass rod, a funnel and a filter paper, describe how

this student could separate sodium chloride from the other substances.

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

[5]

ii) Draw a labelled diagram to show how you would set up the apparatus to

perform this separation technique.

[3]

iii) The sodium chloride obtained above would still be mixed with water. State

how you would be able to obtain dry sodium chloride from this solution.

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

[2]

Chemistry – Form 3 Secondary – Track 2 – 2016 Page 9 of 12

b) The remaining two substances can be separated by using the following apparatus: a

Bunsen burner, a tripod, a wire gauze, a basin, a funnel and cotton wool.

i) Describe how you would separate iodine from copper(II) oxide.

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

[5]

ii) Draw a labelled diagram to show how the equipment was set up.

[3]

c) The student also found two liquid mixtures in the laboratory which needed to be

separated from each other. For each of the mixtures below, choose a separation

technique that would be appropriate in each case.

i) A mixture of water and oil.

_______________________________________________________________

[1]

ii) A mixture of water and ethanol.

_______________________________________________________________

[1]

Page 10 of 12 Chemistry – Form 3 Secondary – Track 2 – 2016

8 Oxygen is an important gas that has many uses. It supports combustion and is used by

aerobic organisms to respire. It reacts with most elements. Oxygen is produced on a

large scale by the fractional distillation of liquid air and can also be produced in the

laboratory.

a) The following statements describe how oxygen is produced industrially by the

fractional distillation of liquid air. They are not in order.

A. The liquid air is passed through a fractionating column and is fractionally

distilled.

B. Oxygen comes out in the second fraction. Other fractions contain the

noble gases.

C. The first fraction contains nitrogen gas.

D. Dust, water vapour and carbon dioxide are removed from the air.

E. The remaining gases (N2, O2 and noble gases) are compressed and cooled

to form a liquid.

Write the letters of the above statements in the correct order.

____________________________________________________________________

[5]

b) Oxygen can be produced in the laboratory using hydrogen peroxide and manganese

dioxide as starting materials.

i) Using the following equipment, draw a labelled diagram showing how you

would set up the apparatus:

Flat bottomed flask, rubber bung, delivery tube,

tap funnel, basin, gas jar, beehive shelf.

[4]

Chemistry – Form 3 Secondary – Track 2 – 2016 Page 11 of 12

ii) List the steps required to produce oxygen using the above equipment.

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

[4]

c) How would you change your setup to produce dry oxygen?

____________________________________________________________________

____________________________________________________________________

[2]

d) Complete the following chemical equation:

2H_O2( _ ) 𝑀𝑛𝑂2 → _H2O( _ ) + O_( _ )

[3]

e) What type of oxide would be produced when oxygen reacts with:

i) Sulfur?

_______________________________________________________________

[1]

ii) Magnesium?

_______________________________________________________________

[1]

9 Hydrogen is the lightest gas. It was discovered by Henry Cavendish

in 1766. He showed that it burns to form water. Later, Antoine

Lavoisier gave the gas its name hydro-gen meaning water-former.

a) Dry hydrogen can be produced in the laboratory using zinc and hydrochloric acid.

i) Using the following equipment, draw a labelled diagram for the production of

dry hydrogen:

Flat bottomed flask, rubber bung, thistle funnel,

delivery tubes, U-tube, gas syringe.

[5]

Page 12 of 12 Chemistry – Form 3 Secondary – Track 2 – 2016

ii) List the steps required to produce dry hydrogen.

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

_______________________________________________________________

[5]

b) Complete the following chemical equation:

Zn( _ ) + _ HCl( _ ) → ZnCl _ ( _ ) + H _ (g)

[3]

c) Give 3 physical properties of hydrogen gas.

____________________________________________________________________

____________________________________________________________________

[3]

d) Hydrogen gas reacts with both metals and non-metals. Give the names of the

substances formed when hydrogen reacts with the following elements and state

whether they are ionically or covalently bonded.

i) Oxygen:

_______________________________________________________________

[2]

ii) Sodium:

_______________________________________________________________

[2]