CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Exam-style questions and sample answers have been written by the authors. In examinations, the way marks are awarded
may be different.
ractical Workbook
P
answers
Chapter 1
Practical investigation 1.1
Practical investigation 1.2
Getting started
Getting started
Ice keeps a drink cold on a hot day as any heat
that is absorbed by the drink is used to melt the
ice rather than to increase the temperature of
the liquid.
Students may suggest a variety of answers but
some may already understand that energy changes
accompany changes of state and may link this
to temperatures remaining the same during state
changes.
Recording data
1
2
3
4
5
6
1
Table: Units should be added to the table:
Time / minutes, Temperature / °C
Graph: axes – labelled correctly with time on
x-axis and temperature on y-axis; scale –
suitable for data / more the 50% of graph
paper used; plot – all points plotted correctly
(±1 mm); line of best fit – smooth line passing
through all points / points joined dot to dot
temperature, heating, intermolecular,
molecules, melting, liquid, boiling, gas
a melting point –F
b boiling point – G
c solid – A
d liquid – C
e gas – E
Take readings more frequently / use a data
logger to record data continuously. Repeat the
experiment and calculate a mean temperature
for melting and boiling points. Use a machine
to stir the water.
The melting and boiling points would not be
a fixed temperature but would occur over a
range of temperatures / graph showing the
same.
Recording data
1–5 Dependent on results.
6 Use of data logger / digital thermometer.
7 To allow greater control of the temperature /
so that the stearic acid was not heated too
strongly.
8 Water does not freeze until 0 °C is reached and
this is difficult to achieve in a laboratory.
9 Use an electrical water bath / use a hot plate /
any reasonable suggestion.
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Chapter 1 continued
Exam-style questions
1
a
b
c
d
e
2
a
b
2
1 mark for each correct reading ;
Mass of antifreeze
added / g
Boiling
point / °C
0
100
20
95
40
90
60
95
80
80
100
75
[6]
All points plotted correctly = 3,
2–3 points plotted correctly = 2,
1 point plotted correctly = 1
Smooth line of best fit [1] ;
Anomaly ignored [1] ;
Axes labelled [1] ;
60 g ;
[1]
77–78 °C ;
[1]
Volume of water / method of heating /
method for determining boiling point /
stirring ;
[1]
Repeating the experiment and calculating
a mean temperature for melting and
boiling point [1] ;
Using a machine to stir the water instead
of stirring by hand [1] ;
Salt used on ice (on roads during winter) /
antifreeze used in car radiators [1] ;
Lowers melting point so it melts at a
lower temperature / prevents ice from
forming [1] ;
Salt dissolves and weakens intermolecular
forces between water molecules [1] ;
Salt used in cooking [1] ; to increase
boiling point of water [1] ;
Or any reasonable answer ;
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 2
Practical investigation 2.1
Getting started
Students should be able to suggest the benefits of using models for atomic structure
as the atoms themselves are too small to see. Using models allows the structure of
atoms to be demonstrated visually to aid understanding.
Recording data
1
2
3
4
5
Dependent on results.
As the proton number increases, the mass number increases.
same, same, equal, increases
Protons and neutrons have the same mass / protons and neutrons in nucleus/
electrons orbit in shells
No charges on particles / relative sizes are incorrect / electrons are static /
distances between electrons and nucleus are not to scale
Practical investigation 2.2
Getting started
Chlorine.
It is possible to have a non-whole number value as the relative atomic mass is
calculated from multiple isotopes.
Recording data
1
Element
Isotope 1
Isotope 2
Isotope 3
Carbon
Mass 12 Abundance 98.9%
Mass 13
Abundance 1.1% Mass 14
Chlorine
Mass 35 Abundance 75%
Mass 37
Abundance 25%
Copper
Mass 63 Abundance 69%
Mass 65
Abundance 31%
Bromine
Mass 79 Abundance 50%
Mass 81 Abundance 50%
2
The students will have calculated the relative atomic masses from the data they
recorded in question 1. The values should be close to the values in the Periodic
Table (given in the following table).
3
Element
4
5
6
7
3
The students will have completed the table with the data from the isotope cards.
Relative atomic mass
from calculations
Relative atomic mass
on the Periodic Table
Abundance 0.0001%
Difference = calculated value
– Periodic Table value
Carbon
student’s own answer
12
student’s own answer
Chlorine
student’s own answer
35.5
student’s own answer
Copper
student’s own answer
64
student’s own answer
Bromine
student’s own answer
80
student’s own answer
Dependent on student answers. Any differences are likely either due to rounding
or the number of decimal places used.
Sources of error include: counting / calculations / decimal places / rounding
Collecting data from the whole class / counting each card multiple times
Reference values are the result of lots of investigations and are very reliable.
Using reference values allows scientists to check that their methods work/
identify errors.
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Chapter 2 continued
Exam-style questions
1
2
a
b
a
b
4
i
ii
Oranges ;
Apples have approximately the
same mass as oranges / proton
and neutrons have the same
relative mass ;
iii Grapes ;
iv Grapes are much smaller than
apples or oranges / electrons have
much lower mass than protons
and neutrons ;
Boron ;
Isotope of Q
Isotope 1
Mass number
89
[1]
[1]
[1]
[1]
[1]
Isotope 2
[1] 90
[1]
(89 × 55) + (90 × 45) = 4895 + 4050 [1] ;
Divided by 100 [1] ;
Ar = 89.5 [1] ;
Allow error carried forward from part a
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 3
4
Practical investigation 3.1
Getting started
The properties of
ionic compounds
Students should realise that the ignition tube is
small so any reaction can be seen easily and as the
tube is irreversibly damaged by the process it is
better to use a disposable tube. After the mixture
of iron and sulfur is heated the tube will be
permanently destroyed.
• High melting point • Sodium chloride
• Low melting point
• Sugar
Recording data
• Insoluble in water
• Wax
1
2
• Do not conduct
electricity
3
4
5
6
• Soluble in water
The properties of
Substances tested that
covalent compounds had these properties
Iron sulfide
Substance
Appearance
Magnetic or
non-magnetic?
Iron and sulfur
mixture
Silver and
yellow
Magnetic –
some parts
Iron sulfide
Grey
Non-magnetic
Glowing colour change
To prevent gas (sulfur vapour/sulfur dioxide)
escaping as it is harmful
The reaction was not fully complete
It is possible to combine copper with sulfur;
however, as copper is not magnetic this
investigation would not be useful / copper may
not combine as it is less reactive than iron
1
2
5
6
7
8
By weighing how much solid would dissolve in
a known volume of water
By using an ammeter in place of a bulb
Substances more readily dissolve in water that
is at a higher temperature
Silicon oxide is ionic. It has a high melting
point and will dissolve in water at a higher
temperature
Exam-style questions
1
a
2
a
Student’s own design.
Melts
Conducts
electricity
wax
zinc
chloride
sugar
magnesium
sulfate
b
c
d
sodium
chloride
e
Soluble in
water
3
Silicon oxide
• Zinc chloride
• Conduct electricity • Magnesium sulfate
Practical investigation 3.2
5
Substances tested that
had these properties
Melting/boiling point [1] ; suitable
method described [1] ;
Electrical conductivity when solid/molten
[1] ; suitable method described [1] ;
Solubility in water [1] ; suitable method
described [1] ;
A = Crucible / accept lid [1] ;
B = Bunsen burner [1] ;
C = Heat-resistant mat [1] ;
Arrow pointing into crucible ;
[1]
Oxygen ;
[1]
Safety goggles / standing up / waiting
for crucible to cool down (or any other
sensible suggestion) ;
[1]
Weigh crucible and then weigh crucible
and magnesium [1] ;
Reweigh after reaction is finished [1] ;
Subtract mass of crucible to determine
difference [1] ;
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 4
c
Practical investigation 4.1
1
2
3
4
5
6
7
8
Dependent on results.
Dependent on results.
Any two from: methane, ammonia, water,
carbon dioxide, sulfur dioxide, ethane,
nitrogen dioxide.
Hydrogen chloride
Carbon
Hydrogen and chlorine
Able to see structure that could not be seen
otherwise / able to visualise the compound /
able to determine the chemical formula
Does not show electrons / the actual shape
of the compounds might be different /
limited number of compounds due to colour
restrictions
4
5
Sulfuric acid and magnesium
Symbol equation: H2SO4(aq) + Mg(s) ➞
H2(g) + MgSO4(aq)
Evaporation or distillation
The product was held in the crucible as it
needed to be kept for observation. If the
magnesium had been heated using tongs the
product could have been lost.
Exam-style questions
1
a
b
Practical investigation 4.2
1
2
3
6
Dependent on results.
a Magnesium and oxygen
Word equation:
Magnesium + oxygen ➞ magnesium oxide
b Hydrochloric acid and sodium hydrogen
carbonate
Word equation:
Hydrochloric acid + sodium hydrogen
carbonate ➞ carbon dioxide + sodium
chloride + water
c Sulfuric acid and magnesium
Word equation:
Sulfuric acid + magnesium ➞ hydrogen +
magnesium sulfate
a Magnesium and oxygen
Symbol equation: 2Mg(s) + O2(g) ➞
2MgO(s)
b Hydrochloric acid and sodium hydrogen
carbonate
Symbol equation: HCl(aq) + NaHCO3(s)
➞ CO2(g) + NaCl(aq) + H2O(l)
c
2
a
b
c
Select one colour to represent hydrogen
[1] ;
Select a different colour to represent
oxygen [1] ;
Attach two hydrogen atoms to one oxygen
atom [1] ;
Select the same colour as used in part a to
represent oxygen [1] ;
Select a different colour to represent
carbon (this must be a different colour to
one used for hydrogen in part a) [1] ;
Attach two oxygen atoms to one carbon
atom [1] ;
Ethanol is made of carbon, hydrogen and
oxygen [1] ;
There are three different coloured discs [1] ;
There are enough different colours for
each element to be assigned a colour [1] ;
Hydrochloric acid + sodium hydroxide
[1] ; ➞ sodium chloride + water [1] ;
HCl(aq) + NaOH(aq) ➞ NaCl(aq) +
H2O(l) [1] ;
NaCl(s) + H2O(g) ;
[1]
Reactants
Hydrochloric acid + sodium hydroxide [1] ;
Products
Sodium chloride + water [1] ;
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 5
Recording data
Practical investigation 5.1
Getting started
Any changes in mass are likely to be very small.
If the balance is not precise enough then these
changes will not be measured.
Recording data
1, 2, 3, 4, 6, 7 Dependent on results.
5 Magnesium sulfate:water 1 : 7
8 Copper(II) sulfate:water 1 : 5
9 Heating caused spitting, which would reduce
the final mass of salt, causing a lower salt to
water ratio. The crucible could be heated more
gently over a longer period of time. Water
could be reabsorbed into the salt from the
atmosphere. The experiment could be done in
a room with low water/moisture content.
Practical investigation 5.2
1 Student’s own design.
2 Dependent on results.
3 124 g
4 80 g
5–8 Dependent on results.
9 If the actual yield is much lower than the
predicted yield, the method included a source
of error, e.g. the reaction not complete / error
when weighing masses.
Practical investigation 5.3
Getting started
Open position
Closed position
1–4 Dependent on results.
5 Temperature and pressure
6 Thermometer and barometer or local weather
station value
7 Used a gas syringe to measure the volume of
the gas
8 Repeated the investigation several times and
calculated a mean / ignored any anomalies
Practical investigation 5.4
Getting started
Reduction tube: contains the methane and copper
oxide and is where the reaction takes place in the
absence of oxygen.
Bunsen burner function: provides heat energy to
enable the reaction to take place.
Recording data
1 and 2 Dependent on results.
3 Dependent on results, but the overall ratio
should be 1 : 1
4 CuO
5 Not all of the copper oxide reacted / Some
copper reacted with oxygen in the air and
was converted back to copper oxide / Error in
weighing masses
6 Used a more precise balance / a balance with
more decimal places
Exam-style questions
1
a
b
c
d
i
11.05 ;
ii 40.8 ;
29.75 ;
0.0298 dm3 [1] ; 0.0012 mol [1] ;
0.029 [1] ;
0.0012
[1]
[1]
[1]
24.17 [1] ;
7
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Chapter 5 continued
2
3
8
Weigh eggshell [1] ;
Add excess [1] ; acid (dilute hydrochloric/
sulfuric) [1] ;
Filter the mixture [1] ;
Wash the mixture with distilled water [1] ;
Dry the remaining solid [1] ;
Reweigh the sample [1] ;
Detail of calculation (initial mass − final mass
= mass of calcium carbonate) [1] ;
Detail of calculation of percentage (mass
of calcium carbonate/initial mass × 100 =
percentage calcium carbonate) [1] ;
a i
Roaring blue flame ;
[1]
ii To prevent loss of magnesium oxide/
loss of product ;
[1]
b i
2.500 g/2.5 g ;
[1]
ii 2.500 g − 1.255 g [1] ; = 1.245 g [1] ;
iii Magnesium oxide contains 1.255 g of
magnesium and 1.245 g of oxygen [1] ;
Approximately 1:1 ratio [1] ;
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 6
5
Practical investigation 6.1
Getting started
For copper wires / any use of copper to conduct
electricity / copper used in electronics
Recording data
1
2
3
4
5
6
7
Dependent on results.
Dependent on results and the purity of copper
used, but the difference should be small if the
investigation is done correctly.
The electrode that lost mass was the anode
and the electrode that gained mass was the
cathode. The cathode gained mass as the
copper ions moved from solution to bind to
the cathode. The anode lost mass as copper
ions left the anode and moved into solution.
The copper on the surface of the electrode
could have been rubbed off if a paper towel
was used. Also, the use of a dry rather than
a wet electrode is important as the mass of
solution left on the electrode would have
affected the change in mass calculations.
The electrolyte enables the ions to move from
one electrode to another.
Any impurities in the copper at the anode will
have sunk to the bottom of the electrolyte and
not joined onto the cathode.
The anode would not have lost mass /
impurities would not collect at bottom of
beaker / copper(II) sulfate loses blue colour.
6
7
8
Current: length of time of electroplating /
volume of zinc sulfate / concentration of zinc
sulfate / surface area of copper strip / type of
cathode used (copper).
Time: current / volume of zinc sulfate /
concentration of zinc sulfate / surface area of
copper strip / type of cathode used (copper).
e.g. temperature
Place the beaker in a water bath to control the
temperature.
Repeated the investigation to collect more
data/identify anomalies.
Exam-style questions
1
a
b
c
d
2
e
f
a
Practical investigation 6.2
1
2
3
4
9
Dependent on results.
Dependent on results, but generally the
change in mass should increase as the current
or time increases.
Current: a greater current means that more
zinc atoms were oxidised from the anode and
reduced onto the cathode.
Time: a longer time allowed more zinc cations
to reduce onto the copper strip.
Time: The longer the electroplating process
went on, the more metal ions moved to the
strip causing an increase in mass. Current: The
higher the current, the faster metal ions moved
to the strip increasing the mass.
b
Positive electrode = anode [1] ; negative
electrode = cathode [1] ;
Electrolyte [1] ; copper(II) sulfate [1] ;
the mass of the cathode increases whereas
the mass of the anode decreases ;
[2]
Produces very pure copper / high-quality
copper needed for electronics ;
[1]
Bulb / ammeter ;
[1]
Impurities [1] ; from the anode [1] ;
Use an electrolyte / copper(II) sulfate [1] ;
Use copper electrodes / impure copper at
anode / pure copper at cathode [1] ;
Connect both electrodes to a circuit [1] ;
Apply electrical current [1] ;
Leave for a set amount of time / leave for
30 minutes [1] ;
Description of pure copper forming on
cathode [1] ;
Anode loses mass [1] ; because copper
metal turns into copper ions in solution
[1] ; electrons from copper metal on
the anode are taken by the circuit [1] ;
impurities leave copper at the anode and
settle in the beaker [1] ;
Cathode gains mass [1] ; as copper ions in
solution gain electrons from the cathode
[1] ; and return back to copper metal [1] ;
atoms of which accumulate on the
cathode [1] ;
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 7
5
Practical investigation 7.1
Getting started
Qualitative – Results that give a description
(bubble/no bubbles/colour change).
Quantitative – Results that give a numerical
answer (time/temperature/mass).
7
Recording data
1
2
3
4
5
6
Dependent on results.
a Lead discs/Elodea: This is a chemical
reaction as a gas is being produced
b Burning magnesium: This is a chemical
reaction as energy is being released and
a new product is being formed.
c Zinc and copper(II) sulfate: This is a
chemical reaction as there is a colour
change on the zinc
d Sodium chloride and silver nitrate: This
is a chemical reaction as a precipitate is
formed.
e Copper(II) carbonate: This is a chemical
reaction as there is a colour change.
To provide carbon dioxide for photosynthesis
to take place.
The exact same set-up but without a lamp/
light source or with some way of blocking
light from the beaker (e.g. a box).
Students should find that if carbon dioxide
is given off the gas could be bubbled through
limewater, turning it cloudy.
8
Exam-style questions
1
The insulated cup reduces the heat loss from the
liquid inside to the surroundings. This means that the
temperature changes recorded are more accurate.
2
4
10
Student’s own design.
Dependent on results.
a Exothermic reactions: sodium hydrogen
carbonate and citric acid, sodium
hydroxide and hydrochloric acid,
copper(II) sulfate and magnesium powder.
b Endothermic reactions: ethanoic acid and
sodium carbonate.
To insulate against heat loss.
1 mark for each correct reading ;
[7]
Highest
temperature
reached / °C
25
27
29
34
36
37
38
b
c
d
Getting started
1
2
3
a
Volume of
solution B
added / cm3
5
10
15
20
25
30
35
Practical investigation 7.2
Recording data
The temperature changes would have been
more difficult to detect as heat would have
been lost or gained from the surroundings.
Eventually, when the reaction has finished,
heat is lost or gained from the surroundings
until the solution is at the same temperature as
the surroundings.
To ensure that all of the reactants were mixed
and able to take part in the reaction.
Use a data logger with thermometer
attachment / temperature sensor.
3
See above: cm3 and °C ;
[2]
3
0 cm ;
[1]
The insulated cup is a good insulator so
prevents heat being gained or lost from
the surroundings ;
[1]
e All points plotted correctly = 3,
2–3 points plotted correctly = 2,
1 point plotted correctly = 1 [3] ;
Axes labelled [1] ;
Line of best fit [1] ;
f Conclusion 1 ;
[1]
g Used a lid / thicker insulated cup / better
insulating material cup ;
[1]
Measure initial temperature of the water [1] ;
using a thermometer [1] ; add plaster of
Paris/powder [1] ; repeat measurement of
temperature [1] ; calculate difference [1] ;
positive exothermic / negative endothermic [1] ;
a Copper(II) carbonate in horizontal
boiling tube ;
[1]
b Limewater in vertical test-tube ;
[1]
c Blue flame ;
[1]
d No more bubbles produced / no further
colour change ;
[1]
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 8
Practical investigation 8.1
Exam-style questions
1 and 2 Dependent on results.
3 Increases, 30 °C, 0 °C, steepest, finished
4 Temperature
5 Volume of gas produced
6 Same volume of acid / same mass of
magnesium / same surface area of magnesium /
same length of time
7 Answer dependent on results, but should be
twice as fast as the rate for 30 °C with this
explanation given/extrapolation of the graph
8
1
Source of error
Effect on results
Mass of magnesium /
length of magnesium
Larger piece
produced more gas /
smaller piece less gas
Slow to close
bung after adding
magnesium / gas
escapes before bung
added
Less gas collected in
the syringe
Did not measure acid
accurately / more acid
/ less acid
More gas produced /
less gas produced
Temperature not
constant / acid cools
c
d
e
f
Reaction will be
slower
Practical investigation 8.2
2
g
a
b
1 and 2 Dependent on results
3 Dependent on results (the best catalyst should
be the catalyst with the shortest time to go
clear)
4 Otherwise the reaction would have occurred
too quickly to measure
5 Lower concentrations of solutions / larger
volume of solutions / lower temperature
6 Use of a light meter / data logger/ light sensor
11
a
b
Limewater ;
[1]
Temperature of acid / concentration of
acid [1] ;
Mass of calcium carbonate [1] ;
Volume of acid [1] ;
[Max. 2]
Methyl orange: red [1] ;
Blue litmus paper: red [1] ;
Universal indicator: dark/red orange [1] ;
Time / minutes [1] ;
Volume of gas produced / cm3 [1] ;
All points plotted correctly = 2,
2–3 points plotted correctly = 1 [2] ;
Axes labelled with units [1] ;
Smooth line of best fit for each line [1] ;
Lines of best fit labelled [1] ;
2 minutes [1] ;
Volume of gas did not increase any
further [1] ;
1 minute / less than 2 minutes ;
[1]
H2O2 (aq) [1] ;
H2O (l) [1] ;
O2 (g) [1] ;
Use the same volume of hydrogen
peroxide [1] ;
Use the same mass of catalyst [1] ;
Description of collecting gas produced
(delivery tube / inverted measuring
cylinder / gas syringe) [1] ;
Time taken to produce gas [1] ;
Compare the volume of gas produced in
amount of time / time taken to produce
set volume of gas [1] ;
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 9
Practical investigation 9.1
Exam-style questions
1
2
3
1
4
5
6
Dependent on results.
Neutralisation.
To ensure an alkaline starting point, to reverse
any acidity in the water caused by carbon
dioxide in the air.
Carbon dioxide is less soluble in hot water so,
as it is heated, the carbon dioxide comes out
of solution and back into the atmosphere.
This increases the pH, causing the red colour
to return.
Hydrated copper(II) sulfate ➞ anhydrous
copper(II) sulfate + water
Suggestions may vary, but the simplest form is
to heat the copper (II) sulfate in a boiling tube
with a bung and delivery tube attached. The
other end of the delivery tube can be passed
into a test-tube in a beaker of cold water to
condense the product.
Practical investigation 9.2
1 and 2 Dependent on results.
3 Ammonia + sulfuric acid ➞ ammonium
sulfate + water
4 2NH4OH (aq) + H2SO4 (aq) ➞
(NH4)2SO4 (aq) + 2H2O (l)
5 Added the sulfuric acid in small volumes /
Used a burette to add the sulfuric acid
6 If the indicator was added it would remain
after the water was evaporated-off and
contaminate the ammonium sulfate
7 Use of a pH meter/data logger with pH
attachment
8 Dependent on student answer but should
include: more repeated measurements / use of
indicator with specific endpoint/pH meter /
more precise method for adding sulfuric acid
(burette or smaller intervals in volume) / may
include finding a rough figure with a trial
titration (described).
12
2
3
Start with anhydrous copper(II) sulfate crystals
[1] ;
Heat [1] ;
Colour change from blue to white [1] ;
Allow to cool [1] ;
Add water [1] ;
Colour change from white to blue [1] ;
a Mid-point in the horizontal boiling tube ;
[1]
b Beneath the horizontal boiling tube /
under the crystals ;
[1]
c For safety. If the boiling tube stops being
heated the submerged delivery tube could
suck back water, which would then cause
the boiling tube to crack/break ;
[1]
d To condense the water produced by the
hydrated copper(II) sulfate ;
[1]
e White ;
[1]
a i
Measuring cylinder ;
[1]
ii Spatula ;
[1]
iii Stirring rod ;
[1]
iv Bunsen burner / electric heating plate ;
[1]
b There is more than needed for the reaction
to take place ;
[1]
c Filter out excess solids [1] ;
Heat the filtrate to form crystals [1] ;
Allow to cool/dry crystals to form [1] ;
Wash in distilled water / filter again [1] ;
Dry crystals [1] ;
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Chapter 10
Practical investigation 10.1
Getting started
The insulated cup reduces heat loss to the
surroundings. The beaker is used to hold the
insulated cup and prevent the cup from falling over.
Recording data
1 and 2 Dependent on results.
3 A chemical reaction / displacement reaction
4 Dependent on results, but likely to be
magnesium or zinc
5 Copper because no (displacement) reaction
took place
6 Iron + copper(II) sulfate ➞ iron sulfate +
copper
Fe + CuSO4 ➞ FeSO4 + Cu
Magnesium + copper(II) sulfate ➞ magnesium
sulfate + copper
Mg + CuSO4 ➞ MgSO4 + Cu
Copper + copper(II) sulfate ➞ copper +
copper(II) sulfate (there is no reaction)
Cu + CuSO4 ➞ Cu + CuSO4
Zinc + copper(II) sulfate ➞ zinc sulfate +
copper
Zn + CuSO4 ➞ ZnSO4+ Cu
7
Reaction
Element
Element
8
9
10 Repeated the experiment to get more data and
calculated a mean. Also ignore anomalous
data.
11 Mass of metal / stirring / time of reaction
12 Mass of metal: greater temperature change
as there was more reactant / stirring: caused
more heat loss as the lid was open or lower
temperature change because the reaction took
place much more slowly when the solution was
stirred less / time of reaction: some reactions
may have gone on to generate more heat later.
Practical investigation 10.2
1
2
3
4
5
6
being
oxidised
being
reduced
Iron + copper(II)
sulfate
Iron
Copper
7
Magnesium +
copper(II) sulfate
Magnesium
Copper
8
Copper +
copper(II) sulfate
No reaction
No reaction
Zinc + copper(II)
sulfate
Zinc
Copper
Dependent on results.
That there is no reaction between copper(II)
sulfate and potassium chloride or potassium
bromide. The reaction with potassium iodide
shows that a reaction has taken place and that
this was a redox reaction.
Iodine was present in the solution. This iodine
came from the potassium iodide and shows
that iodine has been reduced as it is no longer
bound to potassium and is present in the
solution as an atom.
Copper(II) sulfate + potassium iodide ➞
copper iodide + potassium sulfate + iodine
Iodine was oxidised and copper was reduced.
Potassium chloride is not a reducing agent and
therefore does not have the reduction potential
that potassium iodide does
Iron(III) sulfate is a reducing agent /
Potassium manganate is an oxidising agent
Starch changed colour which confirmed the
presence of iodine
Exam-style questions
1
a
ii
So that it was possible to calculate the
temperature change
Volume of copper(II) sulfate / size of cup
b
13
i
i
ii
Acidified potassium manganate /
acidified potassium dichromate ;
Acidified potassium manganate:
purple to colourless / acidified
potassium dichromate: orange
to green ;
Aqueous potassium iodide ;
Colourless to brown ;
[1]
[1]
[1]
[1]
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Chapter 10 continued
2
a
i
ii
b
i
ii
iii
c
14
i
ii
Change from blue to colourless / blue
colour becomes less / lighter blue
colour observed ;
[1]
Magnesium changes from silver to
black/red or brown colour appears on
surface of magnesium ;
[1]
2 (as indicated by the Roman
numerals) ;
[1]
Reduction is the removal of oxygen/
the gain of electrons (supplement) ; [1]
Oxidation is the addition of oxygen/
the loss of electrons (supplement) ; [1]
Exothermic ;
[1]
Thermometer/data logger/
temperature probe ;
[1]
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Chapter 11
Practical investigation 11.1
Practical investigation 11.3
Getting started
red / orange / green / blue / indigo / violet or purple
1
2
Recording data
3
1 and 2 Dependent on results.
3 strength, more, neutralise, weaker, alkalis,
vigorous, metal, hydrogen, stronger, lighted,
red
4 The answers will depend on the students’ own
result but should be the following: colour,
orange, 3, red, 1.
5 Sodium hydroxide, sodium carbonate,
magnesium, universal indicator
6 Blue litmus paper, methyl orange – they
only gave a result to confirm acidity but not
strength.
7 Any value lower than the figure for acid X in
the result or the same if it took only one drop
to neutralise acid X.
3
4
5
15
5
Practical investigation 11.4
Methods: See Planning and setting up the
investigation
Recording data
3
4
5
6
Practical investigation 11.2
1
2
4
Student’s own design.
Test
General result
General word
equation
Magnesium
effervescence/
gas produced
salt +
hydrogen (any
order)
Copper(II)
oxide
coloured
compound
produced
salt + water
(any order)
Calcium
carbonate
effervescence /
carbon dioxide
produced /
limewater
cloudy
salt + water
+ carbon
dioxide (any
order)
Blue litmus
turns red
Methyl
orange
turns red
Dependent on results.
purple, alkalis, green, neutralised, ammonium,
gas, blue, yellow
Sodium hydroxide. It should have taken more
drops of acid to neutralise it.
Neutralisation reaction with hydrochloric
acid.
Compare the colour of universal indicator
paper to a colour chart to give a whole
number value
7
8
Dependent on results.
Sulfur (di)oxide, carbon (di)oxide, phosphorus
oxide
Sodium oxide, potassium oxide, calcium oxide
Non-metals formed acidic oxides, metals
formed basic or alkali oxides
pH meter/data logger with pH sensor
Methyl orange and thymolphthalein change
colour in response to pH changes but do not
allow a specific pH value to be determined (no
further colour change takes place even if the
pH changes further).
Exam-style questions
1
a
b
c
Sulfuric, hydrochloric, citric, ethanoic
There would have been no or little reaction as
copper is much less reactive than magnesium.
Universal indicator, pH meter
d
e
Burette ;
[1]
20, 23, 25, 27, 29, 27, 27, 25, 24, 24, 23
[3] ; All correct = 3, 5–10 correct = 2,
1–4 correct = 1
Points plotted correctly [2] ; All points
plotted correctly = 2, 2–3 points plotted
correctly = 1
axes labelled with units [1] ; /smooth
best-fit line [1] ;
26 [1] °C [1] ;
20 [1] cm3 [1] ;
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Chapter 11 continued
2
3
16
Cut up or crush cabbage [1] ;
Add water [1] ;
Details of filtering mixture to produce a
solution [1] ;
Sample of filtrate mixed with acid and colour
change recorded [1] ;
Sample of filtrate mixed with base and colour
change recorded [1] ;
Same volume of alkali [1] ;
Description of titration (using burette) [1] ;
Use of bromothymol blue [1] ;
Stop titration once blue colour turns to green/
reference to endpoint [1] ;
Detail of volume of hydrochloric acid
measured [1] ;
Repeated for other alkali [1] ;
Reference to repeat whole investigation to
obtain more data / calculation of mean / any
anomalous data ignored [1] ;
Conclusion that alkali that requires greater
volume of hydrochloric acid to neutralise it,
is stronger. [1] ;
[Max. 5]
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Chapter 12
Practical investigation 12.1
1
2
3
4
5
6
7
8
2
Calcium carbonate + hydrochloric acid ➞
calcium chloride + carbon dioxide + water
(products in any order)
CaCO3 + 2HCl ➞ CaCl2 + H2O + CO2
Sodium hydroxide + hydrochloric acid ➞
sodium chloride + water
NaOH + HCl ➞ NaCl + H2O
Yellow to orange
The indicator would mean that the salts
formed would contain an impurity
To remove excess/undissolved solids
Repeat the titration three times to calculate a
mean ‘known volume’
3
Practical investigation 12.2
Getting started
•
•
•
•
4
Sodium carbonate = sodium + carbon +
oxygen
Silver nitrate = silver + nitrogen + oxygen
Copper(II) sulfate = copper + sulfur + oxygen
Potassium iodide = potassium + iodine
5
Exam-style questions
1
Recording data
1
Silver
nitrate
Copper(II) Potassium
sulfate
iodide
Sodium
Light
Blue
No
carbonate green
precipitate precipitate
precipitate
Silver
nitrate
Copper(II)
sulfate
17
Light blue Yellow
precipitate precipitate
Brown
precipitate
Sodium carbonate + silver nitrate ➞ sodium
nitrate + silver carbonate
Sodium carbonate + copper(II) sulfate ➞
sodium sulfate + copper(II) carbonate
Silver nitrate + copper(II) sulfate ➞ copper
nitrate + silver sulfate
Silver nitrate + potassium iodide ➞ potassium
nitrate + silver iodide
Copper(II) sulfate + potassium iodide ➞
potassium sulfate + copper iodide (it should be
noted that the copper iodide will form an offwhite precipitate at the bottom of the test-tube
if left to stand; the brown colour observed is a
result of an iodine solution being formed).
Sodium carbonate + potassium iodide. The
salts formed are soluble / no reaction took
place.
Tap water may contain ions (chloride or
fluoride) which could affect the precipitates
formed.
Silver nitrate is very corrosive.
2
a
i
Measuring cylinder ;
[1]
ii Glass rod ;
[1]
b Zinc oxide stopped dissolving/reacting /
solid remains ;
[1]
c Filtering / filtration ;
[1]
d Heat the solution/evaporate the solution
[1] ; until saturation point/crystals start to
form [1]. Leave to cool [1] ;
Add zinc oxide to beaker of hydrochloric acid
[1] ;
Until no more zinc oxide dissolves [1] ;
Detail of stirring/heating mixture [1] ;
Zinc oxide in excess [1] ;
Filter excess out zinc oxide [1] ;
Evaporate zinc chloride solution/heat zinc
chloride solution [1] ;
[Max. 5]
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Chapter 13
2
Practical investigation 13.1
Getting started
Elements in the same group share properties.
Elements become more reactive down a group.
Recording data
1
2
3
4
5
6
Dependent on results.
Hydrogen
Potassium + water ➞ potassium hydroxide +
hydrogen
The group I metals make water more alkaline /
increase the pH
It is too reactive and may be dangerous
pH meter / datalogger with a pH probe
Practical investigation 13.2
a
se of chlorine water / aqueous
U
bromide [1] ;
Use of potassium chloride / potassium
bromide (or any other reasonable halogen
compound) [1] ;
Displacement / colour change when
potassium chloride added to aqueous
bromine / no reaction when potassium
bromide added to chlorine water [1] ;
b Dependent on compounds chosen in
part a but should be similar to:
Chlorine + Potassium bromide ➞
Potassium chloride + Bromine. [1] ;
c Any one from:
Wear eye protection / Ensure the
laboratory is well ventilated / wear
gloves [1] ;
1 and 2 Dependent on results.
3 Chlorine (most reactive), bromine, iodine
(least reactive)
4 Chlorine (most reactive), bromine, iodine
(least reactive)
5 Fluorine would bleach litmus very quickly
(faster than chlorine water)
6 Potassium fluoride would displace bromine
from solution
Exam-style questions
1
a
b
c
d
e
18
Eye protection [1] ; Safety screen [1] ;
i
Hydrogen [1] ;
ii Test: lighted splint [1] ; Result:
Squeaky pop [1] ;
A (most reactive), C, B (least reactive)
[All three 2 marks, one correct 1 mark]
B [1] ;
A [1] ;
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Chapter 14
Recording data
Practical investigation 14.1
Getting started
Students should sketch a circuit diagram similar to
the diagram below:
1
2
3
4
5
6
Recording data
1
2
3
4
5
6
7
8
Student’s own design.
Metals (dependent on sample used): zinc,
magnesium, iron. Non-metals: sulfur, graphite
Answers will depend on the samples used,
but some examples are: I think that sulfur is
a non-metal because it is brittle, yellow and
does not conduct electricity or heat. I think
that magnesium is a metal because it is grey,
malleable and conducts electricity and heat.
grey, yellow, conductors, non-metals, graphite,
heat, Malleability, brittle, Metals
Only a small sample was tested and this may
not be representative of all metals/non-metals
Test density (or description of test) / melting/
boiling points / test ductility /test whether
sonorous or not.
Properties: good thermal conductivity and
malleability.
Use: plumbing / cooking utensils.
A mixture of metals is called an alloy.
brass / stainless steel / etc.
Practical investigation 14.2
Dependent on results.
Dependent on results, but the results should be
in the order: magnesium, zinc, iron, tin, copper
Dependent on results, but the results should be
in the order: magnesium, zinc, iron, tin, copper
Hydrogen
Dependent on results, but sulfuric acid
should be identified as the stronger acid / the
reactions with metals should be more vigorous
in sulfuric acid than in hydrochloric acid
Use of apparatus to measure the volume of
gas produced in a given time / more accurately
count bubbles produced (gas syringe / delivery
tube into water).
Exam-style questions
1
a
b
c
d
e
2
a
Method
1
2
3
4
5
19
Use a pipette to add 2 cm3 of dilute sulfuric
acid to five of the test-tubes and place them in
the rack.
Use a spatula to add a small amount of zinc
to the first tube and observe the reaction. (You
are looking for bubbling.)
Repeat step 2 with the other metals.
Record your findings in a results table.
Repeat steps 1–4 with the tubes containing
dilute hydrochloric acid.
b
Bars plotted correctly [3] ; All bars
plotted correctly = 3, 2–3 bars plotted
correctly = 2, 1 bar plotted correctly = 1
Axes labelled with units [1] ;
Bars labelled [1] ;
C ;
[1]
E Gold is a good conductor of electricity
and E conducts the best of any material
used/highest value in table/largest bar in
graph ;
[1]
Bulb ;
[1]
Hard to see if it is lit / difficult to judge
which material conducts best as a
judgement about brightness has to be
made / an ammeter would allow
quantitative measurement of current so
comparisons between materials are easier ;
[1]
i
Gloves / eye protection /standing up ;
[1]
ii Measuring cylinder / burette ;
[1]
i
X, Z, Y [All three correct 2 marks,
one correct 1 mark]
ii Gas syringe/inverted measuring
cylinder filled with water ;
[1]
iii Hydrogen ;
[1]
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Chapter 15
f
Practical investigation 15.1
1 and 2 Student’s own answers.
3 C, A, D, B (dependent on student results)
4 A = zinc, B = tin, C = aluminium, D = iron
5 Compare data with other groups in the class.
Use another method/electrolyte.
6 Dependent on student results, but should
be larger than the voltage for aluminium
(metal C).
g
h
i
j
Practical investigation 15.2
1
2
3
4
Dependent on results.
Magnesium is the most reactive as it displaced
zinc, iron and copper
Zinc is the second most reactive as it displaced
iron and copper
Iron is the third most reactive metal as it
displaced only copper
Copper is the least reactive as it did not
displace any other metal from its salt.
The metals changed colour as the metal being
displaced from its salt was deposited on the
surface of the more reactive metal.
There was no displacement taking place and
therefore no metal was displaced from its salt.
Exam-style questions
1
a
b
Timer/stopwatch ;
[1]
Correct column titles [1] ; units for
volume [1] ; correct values recorded [4] ;
1 mark for each correct value.
Name of metal
c
d
e
20
2
a
b
Magnesium, aluminium, iron, copper [3] ;
All correct = 3 marks,
2–3 correct= 2 marks, 1 correct = 1 mark
Zinc [1] ; more gas produced than
aluminium/less gas produced than
magnesium [1] ;
Hydrogen ;
[1]
Squeaky pop test / lighted splint [1] ; will
ignite/pop [1] ;
Two variables with way to control from:
temperature of acid [1] ; use a water
bath [1] ; mass of metal used [1] ; weigh
the metal before using it / use the same
mass of metal [1] ; surface area of metal
[1] ; make sure all pieces same shape / all
powders [1] ;
[Max. 4]
Any three of the following improvements:
use an insulated cup / use a lid / use a
digital thermometer / measure mass of
metal added / repeat for each metal and
calculate a mean ;
[3]
1 mark for each metal ;
[4]
Metal powder
Highest
temperature
reached / °C
Zinc
38
Copper
24
Iron
28
Magnesium
41
Volume of gas
produced in 1 minute
/ cm3
Copper
0
Magnesium
43
Aluminium
30
Iron
13
Used a gas syringe ;
[1]
To remove any dirt/grease/oxidation layer ;
[1]
Bar chart [1] ; axes labelled with units
[1] ; correct plot [2] ; All points plotted
correctly = 2,
2–3 bars plotted correctly = 1
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 16
4
Practical investigation 16.1
1
2
3
4
5
Iron, iron metal
Sodium carbonate
Iron oxide + carbon ➞ iron + carbon dioxide
To provide heat energy for the reaction
Reduction reaction
Practical investigation 16.2
1
2
3
4
5
6
7
Copper(II) carbonate ➞ copper oxide +
carbon dioxide
CuCO3 ➞ CuO + CO2
Copper oxide + carbon ➞ copper + carbon
dioxide
CuO + C ➞ Cu + CO2 (balanced: 2CuO + C
➞ 2Cu + CO2)
The copper is more dense than the carbon.
To reduce the copper oxide as the carbon
powder is more reactive
Aluminium can be extracted from molten
bauxite using electrolysis
Practical investigation 16.3
2
Practical investigation 16.4
Getting started
Magnesium is higher up the reactivity series
than copper and is therefore much more reactive.
Magnesium reacts with oxygen during combustion
reactions to produce a bright white flame,
Copper does not react with oxygen as vigorously.
Magnesium will displace copper from compounds
as magnesium is more reactive.
Recording data
Method
1
5
6
7
Students should identify that one tube will
need to be without water (anhydrous calcium
chloride, one without oxygen (boiled water
with oil layer), one with salt (saltwater), and
one with oxygen and water (distilled water).
Method:
1 Collect the equipment.
2 Label the test-tubes 1–4 with the
permanent marker.
3 Add an iron nail to each tube.
4 Add the contents selected to each tube, e.g.
boiled water, anhydrous calcium chloride,
water with a layer of oil, saltwater.
5 Add a bung to each tube and then observe
the tubes every day for 7 days.
1
2
3
4
5
Recording data
1
2
3
21
The most rusting was caused by salt and water
because rusting requires oxygen and water.
Salt speeds up this process. The least rusting
was caused by calcium chloride/tube with
boiled water and layer of oil because calcium
chloride removed water from the air inside
the tube and water is needed for rusting/ the
boiled water had very little dissolved oxygen in
it and therefore rusting could not take place.
Salt, air/oxygen, water
A nail in an empty tube
Nothing because copper is so unreactive it
does not corrode
Student’s own design.
Dependent on student results, but it should be
the nail in saltwater
The nail in calcium chloride and the nail in
boiled water
6
7
Student’s own design.
Dependent on results.
3: grease/petroleum jelly, 6: plastic coating,
7: paint
Magnesium is more reactive than iron; copper
is less reactive.
a Plastic coating: refrigerators, garden
furniture, window frames (or any
reasonable answer)
b Painting: ships, cars, bridges, gates,
buildings (or any reasonable answer)
c Grease: machinery, moving parts (or any
reasonable answer)
d Galvanising: nails, building materials, cars
(or any reasonable answer)
e Sacrificial protection: ships, water pipes
(or any reasonable answer)
This was a control.
That the corrosion indicator changed colour
even when no corrosion occurred, so the
results were not reliable
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Chapter 16 continued
8
9
There may have been gaps in the paint/grease/
plastic which allowed the iron to come into
contact with air/water so corrosion could still
occur.
By forming a protective layer on the surface of
the nail it would prevent oxygen from coming
into contact with the iron and therefore
prevent rusting.
Exam-style questions
1
a
b
c
d
2
a
b
c
d
e
f
22
Heat the copper(II) carbonate in the
boiling tube using the Bunsen burner. [1] ;
After all of the copper(II) carbonate has
changed colour (green to black), add
carbon powder. [1] ; Heat again. [1] ;
Pure copper produced. [1] ;
Copper(II) carbonate [1] ; ➞ copper oxide
[1] ; + carbon dioxide [1] ;
Copper oxide + carbon [1] ; ➞ carbon
dioxide [1] ; + copper [1] ;
Dissolved in acid (e.g. sulfuric) [1] ;
electrolysis [1] ; pure copper forms at
cathode [1] ;
1 mark each for any two from: wires,
architectural, pipes, cooking pans, coins
or any sensible answer ;
[2]
Tube 1 ;
[1]
Has water available [1] ; and oxygen
present [1] ;
Either tube 2 or 3 ;
[1]
If tube 2 chosen – because it has oxygen
[1] ; but no water [1].
If tube 3 chosen – because it has water
[1] ; but no oxygen [1].
Would protect an iron nail from rusting:
zinc [1] ; magnesium [1] ;
Would not protect the nail from rusting:
copper [1] ; tin [1] ; lead [1] ;
Zinc and magnesium are more reactive
than iron. [1] ;
Copper, lead and tin are less reactive than
iron. [1] ;
3
Steel strip added to test-tube [1] ;
Water added to tubes [1] ;
Same volume of water for each tube [1] ;
Different additive added to each tube [1] ;
Same volume/concentration of additive [1] ;
Strips left to react for same length of time [1] ;
Strips observed / look for rusting [1] ;
Idea of comparison of strips [1] ;
Best protection shows least rusting [1] ;
Repeat the investigation [1] ;
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Chapter 17
Practical investigation 17.1
Practical investigation 17.3
1–5 Dependent on results.
6 rusting, iron, iron oxide, oxygen, volume,
water, difference
7 The iron wool will change colour from grey to
red/brown.
8 Rusting is a slow reaction and so, if the tube is
not left for 1 week, the reaction may not have
ended. This would mean that there would still
be oxygen in the tube.
9 A gas syringe would give more precise results.
10 Errors marking the lines, errors while
measuring volume, reaction not yet complete.
11 Students might suggest a variety of methods,
but the general idea should involve a
substance that absorbs carbon dioxide (soda
lime, sodium hydroxide, potassium hydroxide,
etc.) and some closed container with a method
of measuring the volume taken up. Some
students will recognise the need to use larger
volumes as the percentage of carbon dioxide
in the air is very small.
1, 2, 3 Dependent on results.
4 Carbon dioxide increases the temperature
change.
5 Volume of bottle, volume of gas, time in lamp
light, same light intensity, same distance from
lamp, same volume of water in bottles
6 Pass gas through limewater. Colour change
from clear to cloudy white.
7 If the bottle is closer to the lamp, the light
intensity will be higher and this will affect the
temperature change. Light intensity will no
longer be a controlled variable.
8 The bottle placed closer to the lamp would
show a higher increase in temperature.
9 Crush and weigh the tablets. Repeat the
experiment for different masses of tablet.
Practical investigation 17.4
1
2
Practical investigation 17.2
1
2
Student’s own design.
Dependent on student results, but magnesium
and aluminium should show the greatest
corrosion.
3 Dependent on student results, but magnesium
is most likely to corrode.
4 It is the most reactive, highest in the reactivity
series.
5 Dependent on student results, but copper is
least likely to corrode.
6 It is the least reactive, lowest in the reactivity
series.
7 To remove any surface dirt or layers of
oxidised metal that would prevent a reaction
from taking place.
8 The concentration of acid rain in the
atmosphere is much lower than inside the
plastic box.
9 The combustion of fossil fuels that contain
sulfur compounds.
10 Repeated the experiment but used water
instead of sulfur dioxide solution.
23
3
4
5
6
7
8
Dependent on results.
Dependent on student data but there should
be a 5–20 °C decrease in melting point for
water sample A. Sample B should be close to
no difference.
Dependent on student data but there should
be a 1–5 °C increase in the boiling point for
water sample A. Sample B should be close to
no difference.
Dependent on student data.
Melting Boiling Dissolved
point
point
substances
Water sample A ✗
✗
✗
Water sample B ✓
✓
✓
Use of digital thermometer/thermometer with
smaller intervals/data logger
Repeated each investigation more than once/
calculate mean/remove anomalies
The use of a control would enable the method
and apparatus to be checked. If water boiled
at a temperature other than 100 °C then it
would be clear that there was a problem with
the method.
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Chapter 17 continued
Exam-style questions
1
a
b
c
2
d
e
a
b
c
d
e
f
g
24
Mark the tube every day until the volume
of air inside remains constant. ;
[1]
Boiling tube/test-tube [1] ; / Beaker [1] ;
1 mark for each volume read correctly,
1 mark for each decrease in volume
calculated.
Repeat
Gas syringe
reading / cm3
Decrease in
volume / cm3
1
69
31
2
71
29
3
76
24
4
64
36
30 [1] cm3 [1] ;
0 [1] cm3 [1] ;
Silver is expensive. [1] ; / Silver is a soft
metal. [1] ;
Aluminium ;
[1]
Very corroded / more corrosion than
aluminium / completely corroded /
magnesium dissolves completely ;
[1]
Universal indicator / pH meter / data
logger with pH attachment ;
[1]
All points correctly plotted [3] ; All points
plotted correctly = 3, 2–3 points plotted
correctly = 2, 1 point plotted correctly = 1
Best-fit line or dot to dot [1] ;
Axis labels [1] ;
Day 5 ;
[1]
Day 10 [1] ; Acidity decreased / lake
became less acidic [1] ;
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 18
3
Practical investigation 18.1
Getting started
There are many different examples that could be
used but all should show the following key features:
Saturated compound:
Has a single bond between each of the carbon
atoms
Has more hydrogen atoms
Unsaturated compound:
Has one or more double bonds between the carbon
atoms
Has fewer hydrogen atoms (as there are extra bonds
between carbon atoms)
4
5
6
1
3
4
Student’s own design.
Saturated
hydrocarbons
Unsaturated
hydrocarbons
coconut oil
hexene
unknown sample A
unknown sample B
Product
Test result
with aqueous
bromine
Test result with
dilute acidified
potassium
manganate(VII)
Milk
colourless
colourless
Olive oil
orange-brown
purple
Sesame oil orange-brown
purple
Cream
colourless
colourless
Increases the validity of the results / confirms
first experimental result / easier to see the
result of one test than the other.
Practical investigation 18.2
Liquid
Test 1
Test 2
butan-1-ol
smell produced
no result
Test 1 Alcohols reacts with ethanoic acid to
produce a smell
Test 2 Alcohols do not react with sodium
hydrogen carbonate
Exam-style questions
Recording data
1
2
The alcohols should all produce the same
reactions for both test 1 and test 2.
Safety aspect of smelling products/difficult to
compare smells/not numerical data
2
Samples in (dry) test-tubes [1] ;
Add aqueous bromine [1] ;
Add bung and shake [1] ;
Colour change from orange-brown to
colourless in unsaturated hydrocarbons [1] ;
Saturated hydrocarbons no colour change [1] ;
Wear goggles [1] ;
Wear gloves [1] ;
a i
A compound with no carbon–carbon
double or triple bonds ;
[1]
ii Litmus paper/universal indicator/pH
meter/methyl orange/any reasonable
indicator ;
[1]
b Bromine water/aqueous bromine ;
[1]
c i
carboxylic acids: 1 and 4 ;
[1]
ii alkanes 2 and 3 ;
[1]
iii alkenes 5 ;
[1]
d Temperature is a physical property [1] ;
Homologous series have similar chemical
properties / Homologous series do not
have the same physical properties [1] ;
Getting started
There will be a neutralisation reaction. Description
of effervesce and change in overall pH observed.
Recording data
1
2
25
Dependent on results.
Dependent on results but the alcohols should
all produce similar results for test 1 (smell
produced) and no reaction for test 2. The
carboxylic acids should produce no reaction
for test 1 and effervesce for test 2.
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 19
Practical investigation 19.1
Exam-style questions
1
2
1
3
4
5
6
Student’s own design.
glucose, carbon dioxide, yeast, respiration,
bread
Carbon dioxide
Ethanol is flammable and so combustion
could be used as a test.
As a control / to show a comparison
To stop oxygen from reaching the mixture /
to make sure that anaerobic respiration took
place
Practical investigation 19.2
Ethanol
H
H
H C O H
H
H C
H
H
C O H
H
Propan-1-ol
H
H C
H
c
d
2
a
b
Getting started
Methanol
a
b
H H
c
C C O H
H H
Recording data
1 and 2 Dependent on results.
3 Butanol (accept butan-1-ol and butan-2-ol)
and ethanoic acid
4 Concentrated sulfuric acid is very corrosive /
as a safety precaution
d
A = bung [1] ; B = test-tube [1] ;
X is an oil layer [1] ; prevents oxygen from
reaching the yeast / promotes anaerobic
respiration [1] ;
Y is limewater [1] ; turns cloudy in the
presence of carbon dioxide [1] ;
The liquid (limewater) would remain clear
[1] ; no carbon dioxide produced [1] ;
as yeast killed by high temperature [1] ;
enzymes denatured [1] ;
A = boiling tube/gas jar [1] ; B = delivery
tube [1] ; C = Bunsen burner [1] ;
i
Porcelain chips/fragments [1] ;
ii Catalyst / to speed up the reaction [1] ;
There is no valve fitted to the end of the
delivery tube [1] ;
Suck-back of the cold water into the hot
boiling tube is likely to occur [1] ;
Aqueous bromine [1] ; decolourised [1] ;
Practical investigation 19.3
1
2
3
4
5
6
26
Dependent on results.
The gas burns easily with a yellow flame
therefore it contains a short-chain alkane.
The gas decolourises aqueous bromine
therefore it contains an alkene.
As the boiling tube was heated, the air inside
expanded.
To prevent suck-back occurring as the air
inside the boiling tube cooled and contracted
As a catalyst
To increase the rate of reaction / Energy is
needed to break the bonds in the long-chain
hydrocarbon/liquid paraffin
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 20
Practical investigation 20.1
5
Method
1
Independent variable: Type of fuel
Dependent variable: Temperature change of
water
Control variables:
Time heated for, volume of fuel, starting
temperature water, distance between flame and
boiling tube
I will make my results accurate by: keeping the
thermometer in the water, reading the value
from the thermometer carefully
I will make my results reliable by: taking
repeat readings, completing the experiment
more than once.
Diagram of apparatus:
thermometer
6
Recording data
2
3
4
5
6
25 cm3 water
boiling tube
ceramic wool
heat-resistant mat
To make sure I work safely, I will:
Wear eye protection/not ingest paraffin or
ethanol.
Method:
1 Weigh the crucible and record the mass.
Use the pipette to add ethanol to the
crucible until approximately 1 g has been
added. Record the mass.
2 Fix the boiling tube to the clamp and
stand. Measure 20 cm3 of water using the
measuring cylinder and pour this into the
boiling tube.
3 Place the thermometer in the water in the
boiling tube and leave it for one minute.
Record the temperature shown.
4 Place the crucible with ethanol on the
heat-resistant mat. Lower the boiling
tube of water so that it is just above the
crucible. Light the ethanol using a match.
27
Allow the ethanol to burn until it goes
out. Record the highest temperature
reached by the water.
Repeat the experiment with paraffin.
Student’s own design.
Answer dependent on student results but
should look something like this, with students’
results included:
Paraffin was the better fuel as it caused a
greater increase in the temperature of the
water than ethanol. Paraffin caused an
increase from °C to °C, which was a
total increase of °C. This was more than
ethanol, which only increased the temperature
of the water by °C.
Heated up the boiling tube/crucible/
surroundings/air
Used a calorimeter/lid on boiling tube
Economic reasons, i.e. cheaper / more widely
available /convenient / already own machines
that run on fossil fuels / unaware of problems
caused
Practical investigation 20.2
1–4 Dependent on student results and the
polymers used.
5 Some samples may have bubbles / Some
polymers are not ‘pure’ and may contain fillers
or more than one polymer
6
Tube 1
2
3
4
5
X
7
S
S
F
F
F
Polymers added to different solutions/density
identified by buoyancy or if know volume
and mass density of polymer can be used to
identify unknow samples/compare to know
values of polymers
Exam-style questions
1
a
b
Repeat 1 = 3 °C, repeat 2 = 13 °C, repeat 3
= 5 °C (1 mark for each correct value) ; [3]
Repeat 1 = 35 °C, repeat 2 = 20 °C, repeat
3 = 35 °C (1 mark for each correct value) ;
[3]
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 20 continued
c
d
2
Mean temperature change for methanol
= 7 °C [1] ;
Mean temperature change for paraffin
= 30 °C [1] ;
x-axis fuels / y-axis average temperature
change [1] ; units °C [1] ; correct bars
plotted [1] ; bars not touching [1] ;
a
Long-chain molecules built up from a
large number of monomer molecules ; [1]
b
Polymer
W
Change in
mass / g
−0.025
X
0.000
Y
−0.070
Z
0.000
All correct [2] ;
One error [1] ;
More than one error [0] ;
Polymer
c
d
28
Change in
mass / g
W
0.000
X
−0.065
Y
0.000
Z
−0.060
All correct [2] ;
One error [1] ;
More than one error [0] ;
i
Polymer X [1] ;
Polymer Z [1] ;
ii Polymer W [1] ;
Polymer Y [1] ;
Boiling point [1] ;
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 21
b
Practical investigation 21.1
Getting started
a
b
c
d
i
ii
crystallisation/evaporation
magnetism
distillation
filtration
iii
iv
Method
1
a
b
i
ii
iii
iv
i
ii
iii
iv
v
2
a
i
ii
iii
iv
v
Filtration
Magnetism
Distillation/crystallisation
Crystallisation/distillation
Place a filter paper inside a funnel.
Place the funnel in a conical flask.
Slowly pour the mixture into the
funnel.
When all of the liquid has passed into
the conical flask, remove the funnel.
Carefully remove the wet filter paper
with insoluble solid collected inside it,
open it out, then allow it to dry.
Place the solution in a conical flask or
boiling tube.
Attach a delivery tube to the top.
Set up a second boiling tube in a
beaker of iced water.
Place the end of the delivery tube in
the second boiling tube.
Heat the solution until it boils and
collect the liquid that condenses in
the second tube.
v
c
i
ii
iii
Set up a Bunsen burner with a tripod
and gauze.
Pour the solution into an evaporating
basin.
Place the evaporating basin on the
gauze.
Heat the evaporating basin on a
gentle blue flame until the water
begins to boil.
Stop heating before all of the liquid
boils away. Allow to cool and collect
the solid from the evaporating basin.
Place the two solids into a beaker.
Cover a magnet in plastic wrap then
dip it into the beaker.
Remove the magnet from the beaker
and then observe the surface for any
material that remains. Blow gently to
remove any loose material.
Evaluation
3
4
Anhydrous cobalt(II) chloride (changes colour
from blue to pink) or anhydrous copper(II)
sulfate (changes colour from white to blue) if
water is present,
Acidified silver nitrate (a cloudy white
precipitate is formed if chloride ions (NaCl)
are present).
Practical investigation 21.2
Getting started
X: Rf = 0.67, Y: Rf = 0.40, Z: Rf = 0.43.
Recording data
1–3 Dependent on results.
4 Answer dependent on results, but there must
be comparison/reference to Rf values.
5 Answer dependent on results, but there must
be comparison/reference to Rf values.
6 Volume of dye added to chromatogram –
measure the volume used / Position dye added
not the same for each dye – add all dye to the
line only.
29
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 21 continued
Exam-style questions
1
a
b
c
d
e
2
a
b
c
30
Chromatography ;
[1]
Water ;
[1]
A pencil ;
[1]
Origin / baseline ;
[1]
i
A [1] ; / B [1] ;
ii B [1] ; / C [1] ;
A = round-bottomed flask [1] ;
B = beaker [1] ;
C = tripod [1] ;
D = thermometer [1] ;
E = condenser / Liebig condenser [1] ;
Arrow from the hole on the bottom of the
condenser running through and then out
of the top ;
[1]
Arrow going upwards towards the roundbottomed flask ;
[1]
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 22
Practical investigation 22.1
1
2
3
4
5
6
Sample
Colour observed
Lithium chloride
red
Sodium chloride
yellow
Copper chloride
blue green
Potassium chloride
lilac
Sample X
red
Sample Y
lilac
Sample Z
brick red
X = lithium; Y = potassium; Z = unidentified
(some students might suggest lithium)
Z
Internet/online sources / textbook / reference
book
Splints soaked in distilled water
Practical investigation 22.2
1
2
3
4
5
The rough results were not accurate and it is
likely that the endpoint of the reaction was
missed.
7 Results that do not fit in with the others /
stand out from the others / are far from the
mean
8 To make sure that all of the acid and alkali
mixed properly
9 To make it easier to see the colour change
10 Dependent on results, but they may have
identified finding the endpoint of the
investigation difficult or adding small amounts
of acid from the burette
11 Use of a pH meter or different indicator that
showed the endpoint more clearly / more
repeats or data
Exam-style questions
1
Dependent on results. See Tables 22.2–22.5 in
the Coursebook for expected results.
The gas is carbon dioxide
White precipitate
Barium sulfate
Ammonia
a
b
2
a
b
c
Practical investigation 22.3
1
2
3
4
5
Dependent on results. See Tables 22.2–22.5 in
the Coursebook for expected results.
See Figure 22.7 in the Coursebook for an
example of a suitable flow diagram
Ammonia gas is present / alkaline gas
Zinc ions / Zn2+
The results of the test may be caused by the
contaminant and not the cation being tested.
d
e
f
Any suggestion from: eye protection /
heat-resistant mat / hair tied back /
standing up / any sensible suggestion ; [1]
A = potassium [1] ; B = copper [1] ;
C = lithium [1] ;
Effervescence / fizzing / bubbles ;
[1]
Chloride [1] ; bromide [1] ;
Add ammonia solution [1] ; chloride
precipitate dissolves / bromide precipitate
does not dissolve [1] ;
Damp red litmus paper ;
[1]
Damp red litmus paper turns blue ;
[1]
2+
Zinc ions / Zn ;
[1]
Practical investigation 22.4
1
2
3
4
5
31
Dependent on results.
0.025 mol / dm3
0.025 mol / dm3
Dependent on student results, but should be
close to 25 cm3
Dependent on student results, but should
equal 0.025 mol/cm3 × 1000 / mean volume
(cm3)
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CAMBRIDGE IGCSE™ CHEMISTRY: PRACTICAL WORKBOOK
Chapter 22 continued
3
Salt
Sodium hydroxide
added / and in excess
Ammonia solution
added / and in excess
Dilute nitric acid added
and silver nitrate added
Calcium chloride
white precipitate,
insoluble in excess
no precipitate
white precipitate
Zinc iodide
white precipitate,
soluble in excess
white precipitate,
soluble in excess
yellow precipitate
Chromium(III) bromide
green precipitate,
soluble in excess
green precipitate,
insoluble in excess
cream precipitate
[9]
4
32
Separating the bottle into samples / different
tubes [1] ;
Test for anions:
Add acid and test gas given off for carbonates
[1] ; positive test limewater goes cloudy [1] ;
Acidify with acid and add silver nitrate to test
for halide ions [1] ; white precipitate chloride,
cream precipitate bromide, yellow precipitate
iodide [1] ;
Acidify with nitric acid and add barium
nitrate / acidify with hydrochloric acid and
add barium chloride to test for sulfates [1] ;
positive test white precipitate [1] ;
Add dilute hydrochloric acid and potassium
manganate solution to test for sulfites
[1] ; positive result potassium manganate
decolourises purple to colourless [1] ;
Add sodium hydroxide and aluminium foil/
alumina powder and heat carefully [1] ; test
with damp blue litmus paper [1] ; positive test
damp red litmus paper turns blue [1] ;
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