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Question 1
Steel is usually harder than pure iron. What structural feature of an alloy best explains this?
A.
Different-sized atoms distort the lattice and hinder layer sliding
B.
Covalent bonds replace all metallic bonds in the lattice
C.
The metal ions become fixed by strong ionic bonds
D.
Electrons are removed so the lattice has no attraction
Question 2
Addition polymerization of an alkene has atom economy for the polymer product. What is the reason?
A.
All atoms from the monomer are incorporated into the polymer
B.
The polymer contains fewer atoms than the monomers
C.
Only the atoms in the double bond enter the polymer
D.
Water is the only product formed in the reaction
Question 3
A dicarboxylic acid reacts with a diol in a condensation polymerization. What polymer type and small molecule are formed?
A.
Addition polymer and water
B.
Polyamide and water
C.
Polyester and hydrogen chloride
D.
Polyester and water
Question 4
A solid is lustrous, brittle and has electrical conductivity between that of a metal and an insulator. What bonding description best accounts for these properties?
A.
A simple molecular solid with only weak intermolecular forces
B.
A covalent network with some metallic character
C.
A metallic lattice with layers that slide easily
D.
An ionic lattice with mobile ions in the solid
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Question 5
The electronegativities of atoms X and Y in a binary compound are 0.8 and 2.8. What coordinates should be used to place the X-Y bond on a bonding triangle, using and ?
A.
,
B.
,
C.
,
D.
,
Question 6
Most plastics are poor electrical conductors. What structural reason best explains this property?
A.
They have strong ionic attractions between polymer chains
B.
They have covalent chains but no mobile charged particles
C.
They contain small molecules with mobile ions
D.
They contain electrons fixed in a metallic lattice
Question 7
The characteristic linkage in a polyamide formed from a dicarboxylic acid and a diamine is:
A.
B.
C.
D.
Question 8
Proteins break down at peptide bonds during digestion. What type of reaction occurs, and what is the role of water?
A.
Condensation; water is a product of linkage formation
B.
Oxidation; water removes electrons from the linkage
C.
Addition; water opens a carbon-carbon double bond
D.
Hydrolysis; water is a reactant that breaks the linkage
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Question 9
A diacyl chloride reacts with a diamine to form a condensation polymer. What polymer type and small molecule are formed?
A.
Polyalkene and hydrogen chloride
B.
Polyamide and water
C.
Polyester and hydrogen chloride
D.
Polyamide and hydrogen chloride
Question 10
The repeating unit formed by addition polymerization of bromoethene, , is:
A.
B.
C.
D.
Question 11
A monomer contains both an amino group, , and a carboxyl group, . What polymerization behaviour is expected?
A.
It can form a polyamide-like chain by condensation with release of water
B.
It can form an addition polymer by opening a carbon-carbon double bond
C.
It can form a polyester by eliminating hydrogen chloride
D.
It cannot polymerize because both functional groups are on one molecule
Question 12
Magnesium oxide and silicon may be compared using a bonding triangle.
Electronegativity values: , , .
Calculate and for the Mg-O bond in magnesium oxide.
[2]
State the value of for a Si-Si bond and the bonding region in which silicon is expected to lie.
[1]
Predict one physical property of magnesium oxide from its position near the ionic region of the bonding triangle.
[1]
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Question 13
A solid has a high melting point, is brittle, does not conduct electricity as a solid, but conducts when molten.
State the bonding model that best accounts for these properties.
[1]
Explain why this solid is brittle but conducts electricity when molten.
[2]
Question 14
Reinforced concrete contains concrete surrounding steel bars. It is used in buildings and bridges.
State what is meant by a composite material.
[1]
Explain why reinforced concrete has properties that are more useful than concrete alone.
[2]
Question 15
A polyester can be prepared from a diol and a diacyl chloride instead of from a diol and a dicarboxylic acid.
State the small molecule eliminated when an acyl chloride group reacts with a hydroxyl group.
[1]
State the type of linkage formed in the polymer.
[1]
Compare the polymer formed using a diacyl chloride with that formed using the corresponding dicarboxylic acid.
[1]
Question 16
Samples of iron-carbon alloys were tested for Vickers hardness and electrical resistivity.
Carbon content / wt% | Vickers hardness / HV | Resistivity / |
|---|---|---|
0.00 | 92 | 9.7 |
0.25 | 128 | 10.6 |
0.50 | 162 | 11.4 |
0.75 | 198 | 12.3 |
1.00 | 236 | 13.2 |
State the effect of increasing carbon content on the hardness of the alloy.
[1]
Explain the change in hardness in terms of metallic bonding and structure.
[2]
Suggest why the electrical conductivity of the alloy is lower than that of pure iron.
[1]
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Question 17
Ethane-1,2-diol, , reacts with butanedioic acid, , to form a condensation polymer. The repeating unit is:
A.
B.
C.
D.
Question 18
The hardness of samples of carbon steel was measured as the percentage of carbon was varied.
State why steel is described as a mixture rather than as a compound.
[1]
Explain the trend in hardness using the metallic bonding model.
[2]
Question 19
Polyethene and poly(chloroethene) are synthetic polymers used as plastics.
Define the term monomer.
[1]
Explain why most plastics are electrical insulators.
[1]
Poly(chloroethene) has a higher softening temperature than polyethene of similar chain length. Explain this difference.
[2]
Question 20
2-Methylpropene undergoes addition polymerization.
Draw the repeating unit of the addition polymer formed from 2-methylpropene.
[2]
State the change in bonding that occurs in the monomer during addition polymerization.
[1]
State the atom economy for this addition polymerization.
[1]
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Question 21
Ethane-1,2-diol reacts with butanedioic acid to form a polyester.
Draw the repeating unit of the polyester.
[2]
State the small molecule released during the polymerization.
[1]
Identify the linkage formed in the polymer backbone.
[1]
Question 22
Glycine, , can form a biological macromolecule by condensation reactions.
State the type of polymer and the type of linkage formed when many glycine molecules join.
[2]
Formulate an equation for the condensation of two glycine molecules to form a dipeptide.
[1]
Explain the role of water in hydrolysis of the polypeptide.
[1]
Question 23
Lactic acid, , can polymerize with itself to form poly(lactic acid), PLA.
Identify the two functional groups in lactic acid that allow it to undergo condensation polymerization.
[2]
Draw the repeating unit of PLA.
[2]
Question 24
The table shows selected properties of some period 3 oxides. The oxides are labelled A to D.
Oxide | Melting point / | Bonding character | Acid-base behaviour |
|---|---|---|---|
A | 1130 | predominantly ionic | alkaline |
B | 950 | ionic with some covalent character | basic |
C | 680 | mixed ionic and covalent | amphoteric |
D | 340 | simple molecular covalent | acidic |
Identify the oxide with the greatest ionic character.
[1]
Describe the trend in bonding character shown by the oxides from A to D.
[2]
Explain why oxide D has a much lower melting point than oxide A.
[2]
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Question 25
The electronegativities of selected elements and a bonding triangle are provided. A student is asked to place several binary substances on the triangle.
Element | Electronegativity / Pauling scale |
|---|---|
Al | 1.61 |
Cl | 3.16 |
Ba | 0.89 |
I | 2.66 |
Calculate and for the Al--Cl bond.
[2]
Use the values for Al--Cl to suggest why aluminium chloride does not behave like a typical high-melting ionic chloride.
[2]
Question 26
The structures of three alkene monomers and selected properties of their polymers are shown.
State the structural feature in each monomer that allows addition polymerization.
[1]
Write the condensed repeating unit formed from chloroethene, .
[2]
Explain why the polymer from chloroethene has a higher softening temperature than polyethene.
[2]
Question 27
A polyester is made from benzene-1,4-dicarboxylic acid and ethane-1,2-diol. The monomer structures and a section of the polymer chain are shown.
Identify the two functional groups that react to form the polyester.
[1]
Write a condensed repeating unit for the polyester.
[3]
State the small molecule released when each ester linkage forms from these monomers.
[1]
Question 28
A protein sample was hydrolysed at different temperatures. The graph shows the concentration of free amino acids formed over time.
Describe the trend shown for the concentration of free amino acids at higher temperature.
[1]
Identify the type of linkage broken during hydrolysis of the protein.
[1]
Explain why hydrolysis is described as the reverse of condensation polymerization for proteins.
[2]
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Question 29
Hexane-1,6-diamine reacts with hexanedioic acid to form nylon-6,6, a polyamide.
Draw the repeating unit of nylon-6,6.
[2]
Explain why both monomers must be bifunctional for a long-chain polymer to form.
[1]
State the products formed by complete hydrolysis of nylon-6,6 under suitable conditions.
[1]
Question 30
The repeating unit of PET, a polyester, is shown.
Deduce the two monomers used to form PET from this repeating unit.
[2]
Explain why formation of PET is classified as condensation polymerization rather than addition polymerization.
[2]
Question 31
Four plastics used for packaging were compared. Each polymer differs in side groups, chain length and the presence or absence of hydrolysable groups.
Plastic | Side groups / main structural feature | Relative chain length | Hydrolysable groups? | Softening temperature / | Tensile strength / MPa | Mass loss in biodegradation test / % |
|---|---|---|---|---|---|---|
A | small alkyl side groups | long | no | 90 | 14 | 4 |
B | branched alkyl side groups | long | no | 115 | 22 | 7 |
C | bulky aromatic side groups | long | no | 150 | 18 | 3 |
D | polar side groups | short | yes (ester linkages) | 70 | 6 | 38 |
Identify the plastic most likely to be suitable for a hot-drink lid, using the data.
[1]
Explain why the plastics are electrical insulators.
[2]
Suggest two structural reasons why plastic D loses the greatest percentage mass in the biodegradation test.
[2]
Question 32
Reinforced concrete consists of concrete surrounding steel bars. Mechanical test data for concrete, steel and reinforced concrete are shown.
Material | Tensile strength / MPa | Strain at break / % |
|---|---|---|
Concrete | 2 | 0.1 |
Steel | 500 | 20 |
Reinforced concrete | 20 | 1.0 |
Compare the performance of concrete and reinforced concrete under tension.
[1]
Explain why steel improves the performance of reinforced concrete.
[2]
Evaluate the statement: "The properties of reinforced concrete can be predicted by classifying it as one bonding type."
[2]
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Question 33
Two routes to a polyamide are compared. Route 1 uses a dicarboxylic acid and a diamine. Route 2 uses a diacyl chloride and the same diamine. Observations during polymer formation are shown.
Feature | Route 1 | Route 2 |
|---|---|---|
acid/chloride monomer | ||
amine monomer | ||
polymer-forming reaction | condensation | condensation |
small molecule formed | ||
observable during formation | polymer forms on heating | rapid polymer formation with steamy acidic fumes |
polyamide fragment |
Identify the linkage in the polyamide chain.
[1]
State the small molecule produced in route 2.
[1]
Explain why both monomers in route 1 must be bifunctional for a long-chain polyamide to form.
[2]
Question 34
Two monomers, X and Y, each contain two functional groups. Their structures and possible polymer products are shown.
State which monomer forms a polyester when it polymerizes with itself.
[1]
State which monomer forms a polyamide-like chain when it polymerizes with itself.
[1]
A chain fragment is formed from four molecules of monomer X in a linear condensation reaction. Determine the number of water molecules released.
[2]
Question 35
A manufacturer is choosing between pure copper and a copper alloy for electrical connectors that must resist deformation during use.
Material | Hardness / HV | Conductivity / % IACS |
|---|---|---|
Pure copper | 50 | 100 |
Brass | 100 | 28 |
Bronze | 110 | 15 |
Phosphor bronze | 150 | 10 |
Use the metallic bonding model to answer the following.
I.
Explain why pure copper is malleable.
[2]
II.
State why copper conducts electricity.
[1]
Explain why adding a small amount of another element to copper usually increases hardness but decreases electrical conductivity.
[2]
Evaluate whether pure copper or the copper alloy is more suitable for the electrical connectors.
[2]
Question 36
Reinforced concrete contains concrete surrounding steel bars. Concrete is strong under compression but weak under tension, while steel is strong under tension and can deform before breaking.
Use bonding models to explain the different mechanical behaviour of the two components.
I.
Explain why steel can deform without the metallic structure immediately breaking apart.
[2]
II.
Suggest why concrete is more brittle than steel.
[1]
Explain why reinforced concrete is described as a composite material rather than a compound.
[2]
Evaluate why reinforced concrete can be more useful as a building material than either concrete or steel alone.
[2]
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Question 37
Lactic acid, , can polymerize to form poly(lactic acid), PLA, a biodegradable polyester.
Lactic acid is an example of a monomer that polymerizes with itself.
I.
Explain why lactic acid can undergo condensation polymerization without a second type of monomer.
[2]
II.
Draw the repeating unit of PLA.
[2]
Explain why PLA is more susceptible to biodegradation than polyethene.
[2]
State one environmental condition that may still slow the biodegradation of PLA in landfill.
[1]
Question 38
Three experimental biodegradable plastics were incubated in moist soil. Their structures and mass loss after incubation are compared.
Polymer | Simplified structure | Mass loss after 8 weeks in moist soil / % |
|---|---|---|
A | carbon–carbon backbone only | 5 |
B | ester linkages in backbone; linear chains | 33 |
C | ester linkages in backbone; cross-linked network | 18 |
Identify the polymer expected to undergo the greatest hydrolysis.
[1]
Explain why ester linkages can increase biodegradability compared with a carbon-carbon backbone.
[2]
Evaluate why polymer C loses less mass than polymer B even though both contain ester linkages.
[2]
Question 39
The table compares an addition polymerization and a condensation polymerization carried out on the same scale. The desired polymer and any small-molecule by-products are listed.
Polymerization | Total mass of reactants / g | Mass of desired polymer / g | Mass of small-molecule by-product / g |
|---|---|---|---|
Addition polymerization | 100.0 | 100.0 | 0.0 |
Condensation polymerization | 100.0 | 82.0 | 18.0 |
Calculate the atom economy for the condensation polymerization using the data.
[2]
Compare the atom economy of the addition polymerization with that of the condensation polymerization.
[1]
Explain the difference in atom economy in terms of the polymerization mechanisms.
[2]
Question 40
Aluminium chloride is often introduced using an ionic model, but its properties are better explained using a bonding continuum. The electronegativity values are: Al = 1.61, Cl = 3.16, Mg = 1.31, O = 3.44, Si = 1.90.
Aluminium chloride contains Al--Cl bonds.
I.
Calculate and for the Al--Cl bond.
[2]
II.
Suggest, using these values, why aluminium chloride should not be placed at the purely ionic corner of the bonding triangle.
[1]
Explain why solid aluminium chloride has a much lower melting point than magnesium oxide and does not conduct electricity as a solid.
[3]
Compare the expected properties of silicon and magnesium oxide in terms of their different positions in the bonding triangle.
[2]
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Question 41
The alkene monomer chloroethene, , is used to make poly(chloroethene), PVC.
Consider the addition polymerization of chloroethene.
I.
Draw the repeating unit of poly(chloroethene).
[2]
II.
Explain why this polymerization has atom economy for the polymer product.
[2]
Explain why chloroethene is a gas at room temperature but PVC is a solid plastic.
[2]
PVC is usually an electrical insulator and is often more rigid than polyethene. Explain these two properties in terms of structure and bonding.
[2]
Question 42
The oxides , and illustrate that bonding changes gradually across period 3.
Classify the bonding character of these period 3 oxides.
I.
State which of , and is expected to have the greatest ionic character and justify your answer.
[2]
II.
Suggest why is described as amphoteric and intermediate in bonding character.
[1]
Compare the expected electrical conductivity of solid and liquid in terms of their particles.
[2]
Discuss why assigning each oxide to a single bonding category can be misleading.
[2]
Question 43
Three plastics used in packaging have different repeating units: polyethene, poly(chloroethene) and polystyrene.
Relate the structures of the plastics to their physical properties.
I.
Explain why these plastics are usually poor electrical conductors.
[1]
II.
Explain why poly(chloroethene) usually has stronger attractions between chains than polyethene.
[1]
III.
Suggest why polystyrene is often more brittle than polyethene.
[2]
Packaging fragments can become microplastics in the ocean. Distinguish microplastic formation from biodegradation.
[2]
Suggest two structural features that could make a plastic more biodegradable.
[2]
Question 44
A polyester can be made from benzene-1,4-dicarboxylic acid and ethane-1,2-diol.
Consider the formation of the polyester.
I.
Identify the two functional groups that react to form each ester linkage.
[1]
II.
Draw the repeating unit of the polyester, showing continuation bonds.
[3]
III.
State the small molecule released during formation of each ester linkage.
[1]
Explain why the monomers must be bifunctional for chain growth to occur.
[2]
Suggest the chemical change that occurs when this polyester is hydrolysed.
[1]
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Question 45
Nylon-6,6 is a polyamide made from hexane-1,6-diamine, , and hexanedioic acid, .
Consider the condensation reaction that forms nylon-6,6.
I.
State the functional groups in the two monomers that react to form an amide linkage.
[1]
II.
Draw the repeating unit of nylon-6,6.
[3]
III.
State the small molecule released when the amide linkage forms from these monomers.
[1]
Hexanedioyl dichloride, , can be used instead of hexanedioic acid. Explain one change in the condensation reaction.
[1]
Compare condensation polymerization of nylon-6,6 with addition polymerization of ethene.
[2]
Question 46
Proteins are biological macromolecules formed from amino acid monomers. A general amino acid contains both and groups.
Consider the formation of a peptide linkage between two amino acids.
I.
Identify the functional groups that react.
[1]
II.
State the type of linkage formed and the small molecule eliminated.
[2]
III.
Explain why amino acids can form long chains rather than only dimers.
[1]
Explain how hydrolysis breaks down a protein chain.
[2]
Suggest why proteins are classified as condensation polymers.
[1]
Question 47
A student prepares a polyamide from equimolar amounts of hexane-1,6-diamine, , and hexanedioic acid, . The student reacts of each monomer. Assume that, for a very long chain, each repeat unit forms with elimination of two molecules of water.
The student reacts of each monomer.
I.
Determine the amount, in mol, of water eliminated.
[2]
II.
Calculate the mass of water eliminated.
[1]
III.
State why this polymerization does not have atom economy for the polyamide product.
[1]
Explain why the polyamide can be hydrolysed, but an addition polymer such as polyethene is much less susceptible to hydrolysis.
[2]
Discuss one reason why condensation polymers can still be valuable materials despite producing small-molecule by-products during manufacture.
[1]
Question 48
A section of a condensation polymer is shown. The polymer has both ester and amide linkages and is being investigated for chemical recycling by hydrolysis.
Analyse the linkages in the polymer chain.
I.
Identify one ester linkage and one amide linkage in the polymer section.
[2]
II.
Suggest the two types of functional groups that must have been present in monomers used to form the ester linkage.
[1]
III.
Suggest the two types of functional groups that must have been present in monomers used to form the amide linkage.
[1]
Explain the chemical changes expected during complete hydrolysis of the polymer.
[2]
Evaluate one advantage and one limitation of using hydrolysis for chemical recycling of this polymer.
[2]
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