Student book answers
Chapter 3
C2 3.1 Acids and metals
In-text questions
A metal salt and hydrogen gas
B Hydrogen gas produces a squeaky pop when a lit splint is placed near it.
Activity
Sulfuric similarities
Plan should include appropriate apparatus list, method, risk assessment, and
consideration for different variables.
An example method would be to place different metals that are known to react
vigorously with HCl in H2SO4 to see if bubbles are produced at a similar rate. The gas
produced can then be collected and tested with a lit splint. Hydrogen is present if a
squeaky pop is produced.
Summary
questions
1 a salt, hydrogen, lead, magnesium, silver (5 marks)
2a Iron chloride and hydrogen. This is because all metal–acid reactions result in a salt and
hydrogen being made. Hydrochloric acid forms chloride salts. (3 marks)
b Presence of hydrogen can be tested with a lit splint. If hydrogen is present, a squeaky
pop can be heard. (2 marks)
3 Visual summary example answers (6 marks):
Most metals react with acids to produce a salt and hydrogen. Bubbles of hydrogen are
produced. Hydrogen can be tested for using the lit-splint test. If hydrogen is present, a
squeaky pop is made. This is due to hydrogen reacting with oxygen to form water. Some
metals react vigorously with acid, for example, magnesium. Some metals react steadily,
for example, iron. Some metals do not react at all with acid, for example, gold. Common
acids in the laboratory are hydrochloric, sulfuric, and nitric acids. Hydrochloric acid
produces chloride salts.
C2 3.2 Metals and oxygen
In-text questions
A (s) for solid, (g) for gas
B Two from: magnesium, zinc, and iron
C magnesium, zinc, iron, lead, copper, and gold
Activity
Fair test?
Jamilla should hold each metal sample using tongs over the Bunsen flame and time
how long it takes for the metal to catch on fire.
The metal that burns the quickest is the most reactive, whilst the one that does not
burn will be the least reactive. Some metals may not burn but may char and appear
with an oxide coating. Jamilla should time how long it takes to make that oxide coating
instead.
Possible improvements:
Use the same mass of metal with the same surface area.
Testing reactivity with acid as well, since metals demonstrate the same reactivity
trends whether burning in oxygen or reacting with acid.
Summary
questions
1 magnesium, oxides, copper, gold (4 marks)
2 2Ca(s) + O2(g) → 2CaO(s) (3 marks)
3 Potassium oxide will be made in an explosive/very vigorous reaction. This is
because the reactivity trends of metals are the same whether burning in oxygen or
reacting with acid. (4 marks)
4 Key points song or rap should include (6 marks):
Metals react with acids to make metal salts and hydrogen. Some metals react with
acids vigorously (magnesium). Some react steadily (iron). Some do not react at all
(gold). Metals follow a similar reactivity trend for reactions with oxygen. Metals react
with oxygen to make metal oxides. Some burn (magnesium). Some form a layer of
oxide on the surface (lead). Some do not react at all (gold).
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This resource sheet may have been changed from the original.
Student book answers
Chapter 3
C2 3.3 Metals and water
In-text questions
A calcium hydroxide and hydrogen gas
B substance in a liquid state (l), substance dissolved in water (aq)
C zinc and iron
Activity
Tim’s tin
From Tim’s data, tin is less reactive than magnesium but more reactive than copper.
In order to learn more about the reactivity of tin, Tim should repeat the reaction with
hydrochloric acid using other metals. He should also carry out the reactions of metals
with water and metals with oxygen for all metals tested. This is because metals follow
similar reactivity trends for all these reactions.
Summary
questions
1 Any six from:
Sodium reacts very vigorously with water.
Sodium is near the top of the reactivity series.
Sodium is more reactive than copper.
Iron is more reactive than copper.
Gold is less reactive than copper.
Gold does not react with oxygen, water, or acid.
Gold is unreactive.
2 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) (3 marks)
3 QWC question (6 marks). Example answers:
Nickel is less reactive than iron.
Iron reacts with water and air but nickel does not.
Iron reacts more vigorously with acid than nickel.
Nickel is more reactive than lead.
Neither nickel nor lead react with water and air, but nickel reacts with acid whereas
lead does not.
C2 3.4 Metal displacement reactions
In-text questions
A A reaction where a more reactive element displaces a less reactive element from a
compound.
B Copper is less reactive than magnesium (lower in the reactivity series).
Activity
Planning paragraphs
Credit suitable prose to explain displacement reactions.
Possible information to include in each paragraph:
What a displacement reaction is.
Displacement of metal salts.
Displacement of metal oxides.
Using the reactivity series to predict displacements.
Summary
questions
1 In a displacement reaction, a more reactive metal pushes out a less reactive metal from
its compound. For example, aluminium displaces iron from iron oxide. (5 marks)
2 Reactions a, c, and d will occur, since the element on its own is more reactive
(positioned higher in the reactivity series) than the metal found in the compound. (8
marks)
3 Credit cartoons that show a scientifically correct explanation of displacement. For
example, Superman (stronger/more reactive element) appearing in front of a couple, and
taking the damsel-in-distress away from the (weaker/less reactive) evil villain. (6 marks)
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Student book answers
Chapter 3
C2 3.5 Extracting metals
In-text questions
A A rock that metals can be extracted from.
B Separate the desired metal compound from the compounds it is mixed with, then use
chemical reactions to extract the desired metal from its compound
C carbon + copper oxide → copper + carbon dioxide
Activity
Ore waste
For an ore of 1000 kg with 50% iron:
percentage wasted = 100% – 50% = 50% mass wasted = 0.5 × 1000 kg = 500 kg
Ore with 16% iron:
percentage wasted = 100% – 16% = 84% mass wasted = 0.84 × 1000 kg = 840 kg
Ore with 70% iron:
percentage wasted = 100% – 70% = 30% mass wasted = 0.3 × 1000 kg = 300 kg
Summary
questions
1 rock, compounds, mixed with (3 marks)
2 mass of copper = 0.06 × 100 kg = 6 kg (2 marks)
3 C(s) + 2ZnO(s) → 2Zn(s) + CO2(g) (2 marks)
4 QWC question (6 marks). Example answers:
Metals can be extracted from their compounds using carbon if the metal is below
carbon in the reactivity series.
This is because carbon is more reactive than the metal in its compound. A
displacement reaction takes place.
For example, carbon + lead oxide → lead + carbon dioxide
If carbon is below the metal in its compound, it cannot be used to extract the
metal. This is because carbon is less reactive. Displacement will not occur. For
example, there will be no reaction between carbon and aluminium oxide. (Credit
correctly balanced formula equations as examples of displacement.)
C2 3.6 Ceramics
In-text questions
A Compounds that include metal silicates, metals oxides, metal carbides, and metal
nitrides.
B Four physical properties from: hard, brittle, stiff, solid at room temperature, strong
when forces press on them but break easily when stretched, are electrical insulators.
One chemical property from: unreactive with water, unreactive with acids, unreactive with
alkalis.
C Three from: buildings, electrical power-line insulators, jet-engine turbine blades, plates,
bowls, mugs, or jugs.
Activity
Splendid ceramics
The article should include information on the usefulness of ceramics presented in an
interesting way for a general audience.
Possible areas of focus:
What are ceramics?
Properties of ceramics and where these properties come from.
Uses of ceramics in technical equipment and in everyday lives.
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This resource sheet may have been changed from the original.
Student book answers
Chapter 3
Summary
questions
1 compounds, silicates, oxides, brittle, hard, high, insulators (7 marks)
2 Materials B, D, and possibly E could be ceramics. This is because they possess
high relative hardness and high melting points. (4 marks)
3 Credit suitable tables with properties of ceramics in one column, and uses of
ceramics in the other (6 marks).
Extra credit should be given where uses are linked directly to the properties of
ceramics, for example:
Hardness and strength for bricks in buildings.
Electrical insulation and lack of reactivity with water for power-line insulators.
High melting points for jet-engine turbine blades.
Unreactive nature of ceramics with water, acids, and alkalis for decorative
ornaments, plates, and so on.
C2 3.7 Polymers
In-text questions
A A substance with very long molecules containing identical groups of atoms that are
repeated many times.
B One from: wool for jumpers and socks, cotton for summer clothing like T-shirts, and
rubber for tyres.
C They are flexible but strong.
Activity
Plotting polymers
Bar charts should have names of the five polymers along the x-axis and density
(g/cm3) on the y-axis.
Axes should be labelled with labels at regular intervals.
Bars should decrease in height from PVC, soft rubber, HDPE, LDPE, to poly(propene).
Summary
questions
1 long, atoms, natural, synthetic, poly(ethene), flexible (6 marks)
2a low density
b poor conductor of heat (4 marks)
3 QWC question (6 marks). Example answers:
PVC is the weakest polymer of the three when pulled.
PVC is harder than nylon but softer than acrylic.
PVC is the densest of the three polymers.
Nylon is stronger than PVC but weaker than acrylic when pulled.
Nylon is the softest.
Nylon is the least dense of the three polymers.
Acrylic is the strongest of the three polymers when pulled.
Acrylic has the highest relative hardness.
Acrylic is less dense than PVC but more dense than nylon.
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This resource sheet may have been changed from the original.
Student book answers
Chapter 3
C2 3.8 Composites
In-text questions
A It is a mixture of materials, each with different properties. The composite material has
properties that are a combination of these properties.
B carbon fibre and a glue-like polymer
C Two from: aluminium, glass fibre, and a glue-like plastic.
Activity
Comparing composites
Callum can put different numbers of masses on the straw and mud blocks, and see
how much force each block can take before breaking.
Independent variable: amount of straw; dependent variable: force (N) taken by block
before breaking; control variables to make the investigation fair: size of block,
amount of mud in each block, method of testing strength, position the mass hanger is
placed on the block each time
Summary
questions
1 mixture, different properties, a combination of (3 marks)
2 Fibreglass has a greater strength when pulled and when squashed than
polyester resin. It is the addition of glass fibres that modify the properties of
polyester resin in these ways. (3 marks)
3 Visual summary example answers (6 marks):
Composites as mixtures of materials.
Combined properties of individual materials in the mixture.
Allows for a better combination of properties for their uses.
Examples (CFRP, glass-fibre-reinforced-aluminium, or fibreglass).
Components that make up the individual composite.
Properties of that composite material.
Uses for the composite material.
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Student book answers
Chapter 3
C2 Chapter 3 summary
End-of-chapter
questions
1 copper – no change
potassium – moves on surface of water, lilac flame
calcium – bubbles vigorously (2 marks)
2a Two from: same sized pieces of metal, same volume of acid, same concentration of
acid. (2 marks)
b Wear eye protection to prevent corrosive acid entering his eye and causing damage. (2
marks)
c zinc – closest to the top of the reactivity series. (1 mark)
d hydrogen (1 mark)
3 hard, brittle, electrical insulator, high melting point (4 marks)
4a lithium hydroxide, hydrogen
b magnesium, oxygen
c zinc chloride, hydrogen
d sulfuric acid, hydrogen (8 marks)
5a X and Z – because the metal elements are more reactive than the metals in the
compounds. In each case the metal element can displace the metal in the compound. (4
marks)
b iron + copper oxide → iron oxide + copper/iron + lead oxide → iron oxide + lead (2
marks)
6 This is a QWC question. Students should be marked on the use of good English,
organisation of information, spelling and grammar, and correct use of specialist scientific
terms. The best answers will provide a methodical approach to the correct identification
of the three solutions (maximum of 6 marks).
Examples of correct scientific points:
Add a small sample of magnesium to each solution.
Those solutions that react are of metal compounds that include a metal that is less
reactive than magnesium.
This is because more reactive metals displace less reactive metals from their compounds
in solution.
The solution that does not react with magnesium is magnesium chloride.
Then add a small sample of zinc to the remaining solutions (zinc chloride and copper
chloride).
The solution that reacts is copper chloride.
This is because copper is less reactive than zinc.
Zinc displaces copper from its compounds in solution.
The solution that does not react is therefore zinc chloride.
Credit answers that state the coloured/blue/green solution is copper chloride.
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This resource sheet may have been changed from the original.
Student book answers
Chapter 3
Answer guide for Case Study
Developing
1–2 marks
Secure
3–4 marks
 Instructions are given for one
 The instructions include two
5–6 marks
Extendi
ng
 The instructions include three
test, such as adding the metals
tests such as adding the
tests such as adding the
to water, to acid, or heating
metals to water, to acid, or
metals to water, to acid, and
the metal in air.
heating the metal in air.
heating the metal in air.
 The instructions state that
 The instructions state that
how the test results show the
the metals that react most
the metals that react most
order of reactivity.
vigorously with these
vigorously with these
reagents are the most
reagents are the most
reactive.
reactive.
 The instructions do not state
 The instructions give one way of
making the test fair, for
example, using similarly- sized
 The instructions give two ways of
 The instructions state that the
pieces of metal, or acid samples
making the tests fair, for
tests can be made fair by using
of the same concentration.
example, by using similarly-sized
similarly-sized pieces of metal,
pieces of metal or samples of
samples of acid of the same
acid of the same concentration.
concentration, Bunsen flames of
 The instructions are not clear,
and would be difficult to follow.
 There is no results table, or
one that is poorly laid out.
Some variables may be
missing from the results table.
 The instructions lack detail, but
overall are clear and easy to
follow.
 The results table is clearly laid
out with all variables involved.
Some units may be missing.
the same temperature, and so
on.
 The instructions are detailed,
clear, and easy to follow.
 The results table is clearly set
out with all variables involved
including their units.
© Oxford University Press 2014 www.oxfordsecondary.co.uk/acknowledgements
This resource sheet may have been changed from the original.