Polymers (Cambridge (CIE) IGCSE Chemistry)

Extended Only

Alkenes are unsaturated hydrocarbons. They show structural isomerism. Alkenes take part in addition reactions and form polymers.

Ethene reacts with each of the following. Give the name and structural formula of each product.

 i) steam

 name of product ..........................................................

 structure of product

 [2]

 ii) hydrogen

 name of product ...........................................................

 structure of product

 [2]

Extended Only

Islay is an island off the west coast of Scotland. The main industry on the island is making ethanol from barley.

Barley contains the complex carbohydrate, starch. Enzymes catalyse the hydrolysis of starch to a solution of glucose.

Alkenes polymerise by addition.

 i) Explain the term polymerise.

 [2]

 ii) What is the difference between addition polymerisation and condensation polymerisation?

 [2]

 iii) Poly(dichloroethene) is used extensively to package food. Draw its structure. The structural formula of dichloroethene is drawn below.

 [2]

Separate: Chemistry Only

Lactic acid can be made from corn starch.

lactic acid

It polymerises to form the polymer, polylactic acid (PLA ) which is biodegradable.

Suggest two advantages that PLA has compared with a polymer made from petroleum.

Extended Only

The structure of PLA is given below.

i) What type of compound contains the group that is circled?

[1]

ii) Complete the following sentence. Lactic acid molecules can form this group because they contain both an ............................. group and an ............................. group.

[2]

iii) Is the formation of PLA, an addition or condensation polymerisation? Give a reason for your choice.

[2]

When lactic acid is heated, acrylic acid is formed.

i) Complete the word equation for the action of heat on lactic acid. lactic acid → ..................................... + ..................................... 

[1]

ii) Describe a test that would distinguish between lactic acid and acrylic acid. test ...............................................................................................................  result for lactic acid ...............................................................................................................  result for acrylic acid ............................................................................................................... 

[3]

iii) Describe a test, other than using an indicator, which would show that both chemicals contain an acid group. test ...............................................................................................................  result ............................................................................................................... 

[2]

Separate: Chemistry Only

Synthetic polymers are disposed of in landfill sites and by burning.

 i) Describe two problems caused by the disposal of synthetic polymers in landfill sites.

 [2]

 ii) Describe one problem caused by burning synthetic polymers.

 [1]

Extended Only

State two uses of synthetic polymers.

Extended Only

The structural formulae of two synthetic polymers are given below.

i) Draw the structural formula of the monomer of polymer A.

 [2]

 ii) Identify the functional group circled in polymer B.

 [1]

 iii) Deduce the two types of organic compound which have reacted to form polymer B.

 [2]

Extended Only

Explain the difference between addition and condensation polymers. Classify A and B as either addition or condensation polymers.

Extended Only

Polymers are made by the polymerisation of simple molecules called monomers.

i) The structural formula of a polymer is given below.

 This polymer is made by addition polymerisation. Draw the structural formula of its monomer.

 [1]

 ii) The two monomers shown below form a nylon which is a condensation polymer.

 Draw its structural formula showing one repeat unit of the polymer.

[3]

iii) Name the natural macromolecule which contains the same linkage as nylon.

 [1]

 iv) Explain the difference between addition polymerisation and condensation polymerisation.

 [2] 

Separate: Chemistry Only

Many polymers are non-biodegradable.

 i) Explain the term non-biodegradable.

 [2]

 ii) State three problems caused by the disposal of non-biodegradable polymers.

 [3]

Separate: Chemistry Only

Many monomer molecules react together to form one molecule of a polymer. This reaction is called polymerisation.

The structural formula of the polymer, poly(chloroethene), is given below. This polymer is also known as PVC.

 i) A major use of PVC is insulation of electric cables. PVC is a poor conductor of electricity.

 Suggest another property which makes it suitable for this use.

 [1]

 ii) One way of disposing of waste PVC is by burning it. This method has the disadvantage that poisonous gases are formed.

 Suggest two poisonous gases which could be formed by the combustion of PVC.

 [2]

Extended Only

i) Deduce the structural formula of the monomer from that of the polymer.

 structural formula of monomer ..................................................

 [1]

 ii) Deduce the structural formula of the polymer, poly(phenylethene), from the formula of its monomer, phenylethene.

 structural formula of polymer ..................................................

 [2]

Extended Only

The carbohydrate, glucose, polymerises to form the more complex carbohydrate starch.

If glucose is represented by

 then the structural formula of starch is as drawn below.

 How does the polymerisation of glucose differ from that of an alkene such as phenylethene?

Domestic rubbish is disposed of in landfi ll sites. Rubbish could include the following items.

 Explain why aluminium, a reactive metal, takes so long to corrode.

Extended Only

Both paper and cotton are complex carbohydrates. They can be hydrolysed to simple sugars such as glucose.

The formula of glucose can be represented as:

 Draw the structural formula of a complex carbohydrate, such as cotton.

Include at least two glucose units.

Separate: Chemistry and Extended Only

i) What is the scientific term used to describe polymers which do not break down in landfill sites?

 [1]

 ii) Styrofoam is poly(phenylethene). It is an addition polymer. Its structural formula is given below. Deduce the structural formula of the monomer, phenylethene.

 [1]

Separate: Chemistry Only

Plastics are polymers. They are formed from their monomers by polymerisation.

Two methods for the disposal of waste plastics are

• burning

• recycling.

Describe one advantage and one disadvantage of each method.

burning ..............................................................................................................................

recycling ...........................................................................................................................

Extended Only

i) There are two types of polymerisation reaction. Give their names and explain the differences between them.

 [4]

 ii) Give the structural formula of a polymer which is formed from two different monomers.

 [2]

Extended Only

There are two types of polymerisation - addition and condensation.

Explain the difference between them.

Extended Only

Poly(dichloroethene) is used to package food. Draw its structure. The structural formula of dichloroethene is shown below.

Extended Only

Enzymes are biological catalysts. They are used both in research laboratories and in industry.

Enzymes called proteases can hydrolyse proteins to amino acids. The amino acids can be separated and identified by chromatography. The diagram below shows a typical chromatogram.

 i) The R_f value of a sample = 

 Some R_f values for amino acids are: 

• glutamic acid = 0.4

• glycine = 0.5

• alanine = 0.7

• leucine = 0.9

 Identify the two amino acids on the chromatogram.

 A is ..............................    B is ..............................

 [2]

 ii) Explain why the chromatogram must be exposed to a locating agent before R_f values can be measured.

 [1]

 iii) Measuring R_f values is one way of identifying amino acids on a chromatogram.

 Suggest another.

 [1]

 iv) The synthetic polymer, nylon, has the same linkage as proteins. Draw the structural formula of nylon.

 [3]

Fermentation can be carried out in the apparatus drawn below. After a few days the reaction stops. It has produced a 12% aqueous solution of ethanol.

 i) Complete the equation.

 [2]

 ii) Suggest a reason why the reaction stops after a few days.

 [1]

 iii) Why is it essential that there is no oxygen in the flask?

 [1]

 iv) What technique is used to concentrate the aqueous ethanol?

 [1]

Separate: Chemistry and Extended Only

Alkenes are unsaturated hydrocarbons. They undergo addition reactions.

Two of the methods of making alkenes are cracking and the thermal decomposition of chloroalkanes.

 i) Complete an equation for the cracking of the alkane, decane. 

  ii) Propene can be made by the thermal decomposition of chloropropane.

 Describe how chloropropane can be made from propane.

 reagents   propane and ..............................

 conditions   ...................................................

 [4]

Separate: Chemistry and Extended Only

The following alkenes are isomers.

 i) Explain why they are isomers.

[2]

 ii) Give the name and structural formula of another hydrocarbon that is isomeric with the above.

 name ......................................................

 structural formula ......................................................

 [2]

Extended Only

Give the name of the product when but-1-ene reacts with each of the following.

steam .........................................................

hydrogen ....................................................

bromine ......................................................

Separate: Chemistry and Extended Only

Alkenes can polymerise.

 i) Deduce the name and structural formula of the monomer from the structure of the polymer.

 name of monomer .......................................................

 structural formula .......................................................

 [2]

ii) Draw the structure of the polymer formed from the following monomer. 

[2]

 iii) Describe the pollution problems caused by the disposal of polymers in landfill sites and by burning.

 landfill sites ..................................................

 [2]

 burning ..................................................

 [1]

Separate: Chemistry and Extended Only

Alkenes are unsaturated hydrocarbons. They show structural isomerism. Alkenes take part in addition reactions and form polymers.

Structural isomers have the same molecular formula but different structural formulae.

Give an example of structural isomerism.

molecular formula ........................................

two structural formulae ........................................ and ........................................

Extended Only

Ethene reacts with each of the following. Give the name and structural formula of each product.

 i) steam

 name of product ..........................................................

 structure of product ..........................................................

 [2]

 ii) hydrogen

 name of product ...........................................................

 structure of product ..........................................................

 [2]

Extended Only

Alkenes polymerise by addition.

 i) Explain the term polymerise.

 [2]

 ii) What is the difference between addition polymerisation and condensation polymerisation?

  [2]

 iii) Poly(dichloroethene) is used extensively to package food. Draw its structure. The structural formula of dichloroethene is drawn below.

 [2]

Separate: Chemistry and Extended Only

A compound X contains 82.76% of carbon by mass and 17.24% of hydrogen by mass.

 i) Calculate the empirical formula of compound X.

 [2]

 ii) Compound X has a relative molecular mass of 58.

 Deduce the molecular formula of compound X.

 [2]

Separate: Chemistry Only

Alkenes are unsaturated hydrocarbons.

 i) State the general formula of alkenes.

 [1]

 ii) State the empirical formula of alkenes.

 [1]

What is meant by the term unsaturated hydrocarbon?

unsaturated ..................................................

hydrocarbon ..................................................

Describe a test that would distinguish between saturated and unsaturated hydrocarbons.

reagent ..................................................

observation (saturated hydrocarbon) ..................................................

observation (unsaturated hydrocarbon) ..................................................

Extended Only

Addition polymers can be made from alkenes. The diagram shows part of an addition polymer.

 i) Draw a circle on the diagram to show one repeat unit in this polymer.

 [1]

 ii) Give the structure and the name of the monomer used to make this polymer.

 structure ..................................................

 name ..................................................

 [2]

 iii) Give the structure of an isomer of the alkene in (e)(ii).

[1]

Extended Only

Alkenes can form polymers.

What type of polymerisation occurs when alkenes form polymers?

Extended Only

Part of the structure of a polymer is shown.

Draw the structure of the alkene from which this polymer can be made. Show all of the atoms and all of the bonds.

Extended Only

Part of the structure of a polyamide is shown.

This polyamide is formed from identical monomers. Complete the diagram to show the structure of one monomer. Show all of the atoms and all of the bonds.

There are two types of polymerisation, addition and condensation.

Explain the difference between these two types of polymerisation.

Some plastics, formed by polymerisation, are non-biodegradable.

Describe two pollution problems that are caused by non-biodegradable plastics.

The polymer known as PVA is used in paints and adhesives. Its structural formula is shown below 

 Deduce the structural formula of its monomer.

A condensation polymer can be made from the following monomers.

 HOOC(CH₂)₄COOH and H₂N(CH₂)₆NH₂

 Draw the structural formula of this polymer.

A South Korean chemist has discovered a cure for smelly socks. Small particles of silver are attached to a polymer, poly(propene), and this is woven into the socks.

i) Give the structural formula of the monomer.

[1]

ii) Draw the structural formula of the polymer.

[2]

iii) Suggest which one, monomer or polymer, will react with aqueous bromine and why?

[2]

To show that the polymer contains silver the following test was carried out. 

The polymer fibres were chopped into small pieces and warmed with nitric acid. The silver atoms were oxidised to silver(I) ions. The mixture was filtered. Aqueous sodium chloride was added to the filtrate and a white precipitate formed.

i) Why was the mixture filtered?

[1]

ii) Explain why the change of silver atoms to silver ions is oxidation.

[1]

iii) Give the name of the white precipitate.

[1]

Propanoic acid is a weak acid.

i) The following equation represents its reaction with ammonia.

CH₃CH₂COOH + NH₃ → CH₃CH₂COO^–+ NH₄⁺

Explain why propanoic acid behaves as an acid and ammonia as a base.

[2]

ii) Explain the expression weak acid.

[1]

Monomers polymerise to form polymers or macromolecules.

i) Explain the term polymerise.

 [1]

 ii) There are two types of polymerisation - addition and condensation. What is the difference between them?

 [2]

An important monomer is chloroethene which has the structural formula shown below.

 It is made by the following method.

 C₂H₄ + Cl₂ → C₂H₄Cl₂ dichloromethane

 This is heated to make chloroethene.

 C₂H₄Cl₂ → C₂H₃Cl + HCl

 i) Ethene is made by cracking alkanes. Complete the equation for cracking dodecane.

 C₁₂H₂₆ → .................... + 2C₂H₄

 [1]

 Another method of making dichloroethane is from ethane.

 C₂H₆ + 2Cl₂ → C₂H₄Cl₂ + 2HCl

 ii) Suggest a reason why the method using ethene is preferred.

 [1]

 iii) Describe an industrial method of making chlorine.

 [2]

 iv) Draw the structural formula of poly(chloroethene).

 Include three monomer units.

 [2]

Synthetic polymers are widely used in the modern world.

Their use has brought considerable advantages to modern life as well as some disadvantages.

 i) Suggest two advantages of a plastic bucket compared to a steel bucket.

 [2]

 ii) Name two uses of man-made fibres, such as nylon and Terylene.

 [2]

 iii) Describe the pollution caused by synthetic polymers.

 [3]

One type of polymer is formed by addition polymerisation.

 i) The structural formula of an addition polymer is given below.

 Give the name and structural formula of the monomer.

 name of monomer ..................................................

 [1]

 structural formula of monomer

 [1]

 ii) Draw the structural formula of the addition polymer formed by the polymerisation of phenylethene. The structural formula of phenylethene is given below.

 [2]

Nylon is made by condensation polymerisation. It has the structural formula shown below.

 i) Name the linkage in this polymer.

 [1]

 ii) Name the natural macromolecules which have the same linkage.

 [1]

 iii) Deduce the formulae of the two monomers which reacted to form the nylon and water.

 monomer ...................................................................................................................

 monomer ...................................................................................................................

 [2]

Esters, fats and polyesters all contain the ester linkage.

The structural formula of an ester is given below.

 Name two chemicals that could be used to make this ester and draw their structural formulae. Show all bonds.

 names .................................................. and ..................................................

 [2]

structural formulae .................................................. and ..................................................

 [2]

i) Draw the structural formula of a polyester such as Terylene.

 [2]

 ii) Suggest a use for this polymer.

 [1]

Cooking products, fats and vegetable oils, are mixtures of saturated and unsaturated esters 

The degree of unsaturation can be estimated by the following experiment. 4 drops of the oil are dissolved in 5 cm³ of ethanol. Dilute bromine water is added a drop at a time until the brown colour no longer disappears. Enough bromine has been added to the sample to react with all the double bonds.

 i) Complete the one blank space in the table.

 [1]

 ii) Complete the equation for bromine reacting with a double bond.

 [2]

 iii) Using saturated fats in the diet is thought to be a major cause of heart disease.

 Which of the products is the least likely to cause heart disease?

 [1] 

A better way of measuring the degree of unsaturation is to find the iodine number of the unsaturated compound. This is the mass of iodine that reacts with all the double bonds in 100 g of the fat.

Use the following information to calculate the number of double bonds in one molecule of the fat.

Mass of one mole of the fat is 884 g.

One mole of I₂ reacts with one mole C=C.

The iodine number of the fat is 86.2 g.

Complete the following calculation.

100 g of fat reacts with 86.2 g of iodine.

884 g of fat reacts with .............................. g of iodine.

One mole of fat reacts with .............................. moles of iodine molecules.

Number of double bonds in one molecule of fat is ..............................

Polymers are extensively used in food packaging. Poly(dichloroethene) is used because gases can only diffuse through it very slowly. Polyesters have a high thermal stability and food can be cooked in a polyester bag.

The structure of poly(dichloroethene) is given below.

i) Draw the structural formula of the monomer.

[1]

ii) Explain why oxygen can diffuse faster through the polymer bag than carbon dioxide can.

[2]

i) A polyester can be formed from the monomers HO-CH₂CH₂-OH and HOOC-C₆H₄-COOH. Draw the structure of this polyester.

[2]

ii) Suggest what is meant by the term thermal stability.

[1]

i) Describe two environmental problems caused by the disposal of plastic (polymer) waste.

[2]

ii) The best way of disposing of plastic waste is recycling to form new plastics. What is another advantage of recycling plastics made from petroleum?

[1]

Alkanes and alkenes are both series of hydrocarbons.

i) Explain the term hydrocarbon.

 [1]

 ii) What is the difference between these two series of hydrocarbons?

 [2]

Alkenes and simpler alkanes are made from long-chain alkanes by cracking.

Complete the following equation for the cracking of the alkane C₂₀H₄₂.

C₂₀H₄₂ → 2C₄H₈ + 2C₂H₄ + ...............

Alkenes such as butene and ethene are more reactive than alkanes.

Alkenes are used in the petrochemical industry to make a range of products, which includes polymers and alcohols.

 i) Dibromoethane is used as a pesticide. Complete the equation for its preparation from ethene.

+ Br2 →

 [1]

 ii) The structural formula of a poly(alkene) is given below.

 Deduce the structural formula of its monomer.

 [2]

 iii) How is butanol made from butene, CH₃–CH₂–CH=CH₂? Include an equation in your answer.

 [2]

 iv) Cracking changes alkanes into alkenes. How could an alkene be converted into an alkane? Include an equation in your answer.

 [2]

20c m³ of a hydrocarbon was burnt in 175 cm³ of oxygen. After cooling, the volume of the remaining gases was 125 cm³. The addition of aqueous sodium hydroxide removed carbon dioxide leaving 25 cm³ of unreacted oxygen.

 i) volume of oxygen used = .......... cm³

 [1]

 ii) volume of carbon dioxide formed = .......... cm³

 [1]

 iii) Deduce the formula of the hydrocarbon and the balanced equation for the reaction.

 [2]

Esters occur naturally in plants and animals. They are manufactured from petroleum. Ethyl ethanoate and butyl ethanoate are industrially important as solvents.

i)        Explain the term solvent.

 [1]

 ii) Give the formula of ethyl ethanoate.

 [1]

 iii) Ethyl ethanoate can be made from ethanol and ethanoic acid. Describe how these chemicals can be made.

 ethanol from ethene ..................................................

 [2]

 ethanoic acid from ethanol ..................................................

 [2]

 iv) Name two chemicals from which butyl ethanoate can be made.

 [1]

A polymer has the structure shown below.

 (i) What type of polymer is this?

 [1]

 (ii) Complete the following to give the structures of the two monomers from which the above polymer could be made.

 [2]

Petroleum is a source of many important chemicals.

Name two industrial processes which must take place to produce alkenes from petroleum.

Ethene, CH₂=CH₂, and propene, CH₂=CHCH₃, can both be converted into polymers.

 i) What type of polymerisation takes place when ethene forms a polymer?

 [1]

 ii) What is the empirical formula of the polymer formed from ethene?

 [1]

 iii) Propene has the structural formula CH₂=CHCH₃.

 Draw two repeat units of the polymer made from propene.

 [2]

Ethene will react with steam to form ethanol.

Propene will react with steam to form two isomers, both of which are alcohols.

Suggest the structures of these alcohols.

Esters are organic chemicals noted for their characteristic smells. Ethanoic acid and methanol will react to form an ester.

 i) Name the catalyst needed to form an ester from ethanoic acid and methanol.

 [1]

 ii) Name the ester formed when ethanoic acid reacts with methanol.

 [1]

 iii) Draw the structure of the ester formed when ethanoic acid reacts with methanol. Show all bonds.

 [2]

 iv) Give the name of a polyester.

 [1]

Alkanes and alkenes are examples of hydrocarbons.

 i) What is meant by the term hydrocarbon?

 [1]

 ii) Give the general formula of straight-chain

 alkanes, ..................................................

 alkenes. ..................................................

[2]

A compound X contains carbon, hydrogen and oxygen only.

X contains 54.54% of carbon by mass, 9.09% of hydrogen by mass and 36.37% of oxygen by mass.

 i) Calculate the empirical formula of compound X.

 [2]

ii) Compound X has a relative molecular mass of 88.

 Deduce the molecular formula of compound X.

 [2]

An ester has the molecular formula C₃H₆O₂.

Name and give the structural formulae of two esters with the molecular formula C₃H₆O₂.

Name the ester produced from the reaction of propanoic acid and methanol.

A polyester is represented by the structure shown.

 i) What type of polymerisation is used for the production of polyesters?

 [1]

 ii) Which simple molecule is removed when the polyester is formed?

 [1]

 iii) Complete the diagrams below to show the structures of the monomers used to produce the polyester. Show all atoms and bonds.

 [2]