Skip to notes
wise otter.Chemistry
Contents
K223 / K225 / 2027
Organic Chemistry

Full chapter

Organic Chemistry

Recognise molecular families and connect structures, reactions, fuels and materials.

SEC G2 Science K223 / K225 (2027)

01

Fuels, fractions and bioethanol

Follow carbon from a resource to useful products.

Make a guess. You are not marked.

Petrol molecules have about 5 to 10 carbon atoms. Bitumen molecules have more than 70. Which fraction has the higher boiling point?

  1. Petrol, as its smaller molecules pack closer
  2. Bitumen, as its larger molecules attract more
  3. Neither; they boil at the same temperature
Show the answer

Bitumen, as its larger molecules attract more

Bigger molecules have stronger attractive forces between them, so more energy is needed to separate them and they boil at a higher temperature.

A hydrocarbon contains carbon and hydrogen only. Natural gas is mainly methane; crude oil is a mixture of hydrocarbons. Both are non-renewable because they form far more slowly than they are consumed. Burning a fuel releases energy, while the same hydrocarbon feedstock may also be valuable for manufacturing chemicals and plastics.

Fractionate crude oil
  1. Heat the oil

    Many components vaporise.

  2. Vapour rises through the column

    The column is hotter at the bottom and cooler at the top.

  3. Condense different fractions

    Higher-boiling, generally larger molecules condense lower down; smaller, more volatile molecules travel higher.

  4. Collect useful mixtures

    Each fraction contains hydrocarbons with a range of boiling points, not necessarily one pure compound.

Crude oil fractions, from the top of the column to the bottom
FractionMolecules and boiling rangeMain use
Petroleum gasSmallest molecules (1 to 4 C); lowest boiling pointsFuel for cooking and heating
Petrol (gasoline)Small moleculesFuel for cars
NaphthaSmall to medium moleculesFeedstock for making chemicals and plastics
Paraffin (kerosene)Medium moleculesFuel for aircraft
DieselMedium to large moleculesFuel for lorries, buses and trains
Lubricating oilLarge moleculesLubricants, waxes and polishes
BitumenLargest molecules; highest boiling points; very viscousRoad surfaces and roofing

As hydrocarbon molecules get larger, melting and boiling points generally rise overall, viscosity increases, and volatility decreases. Smaller fractions are useful fuels; larger fractions may be cracked into more sought-after smaller molecules. The amount supplied by fractional distillation need not match the demand for each fraction. Larger molecules generally have stronger intermolecular attractions, so more energy is needed to separate them and the liquid resists flow more. These are trends within comparable members, not a claim that every individual melting point rises smoothly.

Bioethanol can be made from sugars in a crop such as sugarcane and is renewable if the crop is regrown. Growing plants take in carbon dioxide, partly offsetting carbon dioxide released when the ethanol burns. Fossil fuels instead add carbon stored underground to the active carbon cycle. Biofuel is not automatically emission-free: cultivation, processing, transport and land-use change also affect its impact.

Check your understanding

Why is a crude-oil fraction not a pure substance?

  1. It still contains water and sand that the distillation column cannot remove.
  2. It is a mix of hydrocarbons with similar boiling points that condense together.
  3. Its molecules break apart in the hot column, so new compounds keep forming.
Show the answer

It is a mix of hydrocarbons with similar boiling points that condense together.

Fractional distillation groups compounds by boiling range. Several hydrocarbons boil in the same range, so each fraction is still a mixture.

Check your understanding

Why are natural gas and crude oil described as non-renewable?

  1. They took millions of years to form and are used far faster than they form
  2. They release carbon dioxide into the air whenever they are burned as fuel
  3. They are mixtures of many different hydrocarbons that must be separated
  4. They are found deep underground, so they have to be drilled for
Show the answer

They took millions of years to form and are used far faster than they form

A non-renewable resource cannot be replaced within a human lifetime. Fossil fuels formed from ancient remains over millions of years, so once used they are gone.

Check your understanding

Compared with the bitumen fraction, the petrol fraction has:

  1. smaller molecules, lower boiling points and lower viscosity
  2. larger molecules, higher boiling points and higher viscosity
  3. larger molecules, lower boiling points and higher flammability
  4. smaller molecules, higher boiling points and lower viscosity
Show the answer

smaller molecules, lower boiling points and lower viscosity

Small molecules have weaker attractions between them, so they boil at lower temperatures and flow easily. Petrol condenses near the top of the column.

Check your understanding

Bioethanol is made from sugarcane. Why can burning it add less CO2 overall than burning petrol?

  1. Ethanol contains no carbon atoms, so burning it gives water but no carbon dioxide.
  2. Ethanol burns at a lower temperature, so less of its carbon turns into carbon dioxide.
  3. The growing cane took in CO2, which partly offsets the CO2 released on burning.
Show the answer

The growing cane took in CO2, which partly offsets the CO2 released on burning.

Sugarcane absorbs CO2 for photosynthesis, so burning its ethanol returns carbon recently taken from the air. Petrol releases carbon locked away for millions of years. Farming and transport still use fuel, so it is not fully carbon neutral.

Exam-style question

A refinery records the percentage of its crude oil that ends up in two fractions, and the percentage its customers want.
Petrol: supply 15%, demand 35%.
Fuel oil (large molecules): supply 40%, demand 20%.
(a) Use the data to explain why the refinery cracks some fuel oil. [2]
(b) A molecule of C12H26 is cracked to give octane, C8H18, and ethene only. Write the balanced equation. [1] [3]

Saved on this browser only. Anyone using this browser can see it.

02

Alkanes: build a valid carbon skeleton

Use four bonds per carbon and one per hydrogen.

A homologous series has a common general formula, similar chemical properties and a gradual change in physical properties as molecule size and mass increase. Successive members differ by CH2. Alkanes are saturated hydrocarbons: all carbon-carbon bonds are single. For an unbranched or branched acyclic alkane, the general formula is CnH2n+2.

Shared alkane structures
NameMolecular formulaCondensed structure
MethaneCH4One C with four C-H bonds
EthaneC2H6CH3-CH3
PropaneC3H8CH3-CH2-CH3

To draw a displayed formula, draw the carbon-carbon connections first, then add individual C-H bonds until each carbon has four bonds. A condensed CH3 group stands for three separate hydrogens bonded to that carbon. Count atoms after drawing; moving the page or bending a chain does not create a new compound.

Four bonds around carbon

Methane has four single C-H bonds. Each ethene carbon has two C-H bonds and a double C=C bond, giving four bonds in total.

A double bond counts twice when checking carbon valency; flat drawings do not show molecular shape.

Displayed methane

Complete displayed structure with 1 carbon, 4 hydrogen atoms: CH4. Every bond and hydrogen is shown.

CH4. Count four bonds at every carbon, two at oxygen and one at hydrogen. The flat layout shows connectivity, not molecular shape.

Displayed ethane

Complete displayed structure with 2 carbon, 6 hydrogen atoms: C2H6. Every bond and hydrogen is shown.

C2H6. Count four bonds at every carbon, two at oxygen and one at hydrogen. The flat layout shows connectivity, not molecular shape.

Displayed propane

Complete displayed structure with 3 carbon, 8 hydrogen atoms: C3H8. Every bond and hydrogen is shown.

C3H8. Count four bonds at every carbon, two at oxygen and one at hydrogen. The flat layout shows connectivity, not molecular shape.

Alkanes are generally unreactive, but burn and undergo substitution with chlorine in ultraviolet light. Complete combustion: CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l), showing cooled products. Limited oxygen can produce carbon monoxide and/or soot. Substitution: CH4(g) + Cl2(g) -> CH3Cl(g) + HCl(g), under UV. One H is replaced by Cl; further substitution is possible.

Check your understanding

A saturated, non-cyclic hydrocarbon has three carbon atoms. What is its formula?

  1. C3H12, from CnH4n
  2. C3H6, from CnH2n
  3. C3H8, from CnH2n+2
Show the answer

C3H8, from CnH2n+2

Alkanes follow CnH2n+2, so n = 3 gives C3H8. Check a drawing: each C has four bonds and there are eight H in total.

Check your understanding

Methane, ethane and propane are in the same homologous series. Which statement is not a feature of a homologous series?

  1. The members all have the same boiling point
  2. Each member differs from the next by CH2
  3. The members share the same general formula
  4. The members have similar chemical properties
Show the answer

The members all have the same boiling point

Boiling points rise gradually as molecules get larger and the attractions between them get stronger.

03

Alkenes: a double bond creates new reactions

Distinguish substitution, addition and cracking.

Make a guess. You are not marked.

Orange/brown bromine water is shaken with ethene, and separately with ethane, at room temperature. What do you see?

  1. Neither changes the colour at room temperature
  2. Only the ethene decolourises it, by addition
  3. Both decolourise it, as both are hydrocarbons
Show the answer

Only the ethene decolourises it, by addition

Ethene has a C=C double bond, and bromine adds across it to make a colourless product. Ethane has only single bonds, so nothing adds.

Alkenes are unsaturated hydrocarbons containing a carbon-carbon double bond. For acyclic molecules with one C=C bond, their general formula is CnH2n. Ethene is CH2=CH2; propene is CH2=CH-CH3. Each carbon still has four bonds in total.

Worked exampleExpand an alkene without adding too many hydrogens

Draw propene from CH2=CH-CH3.

Try it first. Then show the worked stepsHide the worked steps
  1. Join three carbon atoms. Put the double bond between the first two; this uses two of each participating carbon's four bonds.
  2. Carbon 1 needs two C-H bonds. Carbon 2 already has three bonds in total to carbons, so needs only one H. Carbon 3 needs three H.
  3. Count the result: C3H6, with four bonds at each carbon.
Answer

Use the displayed propene below as a check. A double bond counts twice for valency but still connects the same two carbon atoms.

Displayed ethene

Complete displayed structure with 2 carbon, 4 hydrogen atoms: C2H4. Every bond and hydrogen is shown.

C2H4. Count four bonds at every carbon, two at oxygen and one at hydrogen. The flat layout shows connectivity, not molecular shape.

Displayed propene

Complete displayed structure with 3 carbon, 6 hydrogen atoms: C3H6. Every bond and hydrogen is shown.

C3H6. Count four bonds at every carbon, two at oxygen and one at hydrogen. The flat layout shows connectivity, not molecular shape.

Aqueous bromine distinguishes an alkene from an alkane under the usual test conditions without UV. The alkene decolourises orange/brown bromine water because bromine adds across C=C. Ethene forms CH2Br-CH2Br. The alkane does not show this addition reaction. The colour change is an observation; unsaturation is the inference.

Ethene reaction pathways
Reagent or processEssential conditionsProduct/change
Oxygen: complete combustionIgnition, sufficient oxygenC2H4 + 3O2 -> 2CO2 + 2H2O
Aqueous bromineRoom conditions; no UV requiredC2H4 + Br2 -> C2H4Br2
HydrogenNickel catalyst, heatC2H4 + H2 -> C2H6
Addition polymerisationSuitable temperature, pressure and catalystMany ethene molecules form poly(ethene)

Cracking breaks larger hydrocarbons into smaller molecules using strong heating, often with a catalyst. Products can include smaller alkanes, alkenes and hydrogen. Examples of possible balanced changes are C10H22 -> C8H18 + C2H4, and C2H6 -> C2H4 + H2. Actual cracking produces a mixture; use atom conservation to deduce a missing product.

Polyunsaturated food molecules contain more than one C=C bond. Hydrogenating unsaturated vegetable oils with hydrogen and a nickel catalyst reduces the number of double bonds, making the product more solid and useful in margarine manufacture. This is addition, not polymerisation.

Check your understanding

C8H18 cracks to C6H14 and one other molecule. What is the other molecule?

  1. C2H2, ethyne
  2. C2H4, ethene
  3. C2H6, ethane
Show the answer

C2H4, ethene

Subtract: 8 - 6 = 2 carbons and 18 - 14 = 4 hydrogens remain, so C2H4. Check both totals.

Exam-style question

Describe a chemical test to distinguish between ethane and ethene. Give the result for each gas. [3]

Saved on this browser only. Anyone using this browser can see it.

Check your understanding

Ethene reacts with hydrogen. Which line gives the condition and the product?

  1. Heated nickel catalyst; ethane
  2. Ultraviolet light; chloroethane
  3. Acid catalyst with steam; ethanol
  4. Yeast at 37 degrees C; ethanol
Show the answer

Heated nickel catalyst; ethane

Hydrogen adds across the C=C bond: C2H4 + H2 -> C2H6. The same reaction hardens vegetable oils into margarine.

Check your understanding

A vegetable oil is polyunsaturated. How is it turned into a solid margarine?

  1. Hydrogen is added to some of its C=C bonds, using a heated nickel catalyst.
  2. Oxygen is added to its C=C bonds, by bubbling air through the warm oil.
  3. Water is removed from the oil by heating, which leaves the solid fat behind.
Show the answer

Hydrogen is added to some of its C=C bonds, using a heated nickel catalyst.

Polyunsaturated means many C=C bonds per molecule. With fewer double bonds the molecules pack more closely, so the melting point rises and the product is a soft solid.

Check your understanding

An unbranched alkene has 5 carbon atoms. What is its formula, and why is it unsaturated?

  1. C5H8; each carbon has one fewer H than in pentane
  2. C5H10; it has a C=C bond, so two fewer H than pentane
  3. C5H12; it can still react, so it counts as unsaturated
Show the answer

C5H10; it has a C=C bond, so two fewer H than pentane

Alkenes follow CnH2n, so n = 5 gives C5H10. The double bond can open to add more atoms, which is what unsaturated means.

04

Addition polymers: open the double bond, keep the substituents

A repeat unit shows the pattern within a long chain.

Make a guess. You are not marked.

Thousands of ethene molecules, CH2=CH2, join to make poly(ethene). What happens to each C=C double bond?

  1. It opens to a single bond and links to the next unit
  2. It breaks fully and the carbon atoms separate
  3. It stays as a double bond along the whole chain
Show the answer

It opens to a single bond and links to the next unit

Addition polymerisation uses one bond of each double bond to join the monomers, so the chain has only single carbon-carbon bonds.

A polymer is a large molecule built from many smaller monomer molecules. Different monomers give different repeating units and properties. In addition polymerisation, the C=C bonds open to link monomers into a chain; no small molecule is eliminated. Poly(ethene) forms from ethene and is used in plastic bags and clingfilm.

Draw an addition polymer
  1. Start with the alkene

    Identify the two carbon atoms of C=C.

  2. Change the double bond to a single bond

    Give each of those carbons a new bond to the next unit.

  3. Preserve every attached group

    Do not detach or lose hydrogens, chlorine atoms or side chains.

  4. Show repetition

    Enclose a repeat unit in brackets, with backbone bonds extending through the brackets and n outside.

Ethene gives the repeat unit [-CH2-CH2-]n. Propene, CH2=CH-CH3, gives [-CH2-CH(CH3)-]n. The CH3 side group stays attached; it does not become a third carbon in the two-carbon backbone repeat.

Poly(ethene): bonds through the brackets

Two backbone carbon atoms have a single bond between them and open bonds passing through the brackets to neighbouring units. Each carbon has two hydrogen atoms.

The n means many repeats. The bonds crossing the brackets join neighbouring units; they are not additional hydrogen atoms. Restoring C=C between the two backbone carbons gives ethene.

Poly(propene): keep the side group

Two backbone carbon atoms have a single bond between them and open bonds passing through the brackets to neighbouring units. A complete CH3 side group remains attached to the second carbon.

The n means many repeats. The bonds crossing the brackets join neighbouring units; they are not additional hydrogen atoms. Restoring C=C between the two backbone carbons gives propene.

Two repeat units of poly(propene)

A chain of four carbon atoms joined by single bonds, with bonds continuing off both ends. Every carbon has one hydrogen on top. Below, the first and third carbons have a hydrogen and the second and fourth carbons have a CH3 group.

When asked for two repeat units, draw four backbone carbons, all with single bonds, plus a bond sticking out at each end to show the chain continues. Each propene unit keeps its CH3 group, on every second carbon.

Worked exampleRecover a monomer

A polymer repeat unit is [-CH2-CHCl-]n. Deduce its monomer.

Try it first. Then show the worked stepsHide the worked steps
  1. Identify the two backbone carbons.
  2. Remove their links to neighbouring repeat units and restore a C=C double bond.
  3. Keep the chlorine attached to the same carbon.
Answer

CH2=CHCl. An unfamiliar monomer can be deduced from bonding without memorising its name.

Check your understanding

Should the repeat unit of poly(ethene) keep the C=C double bond of ethene?

  1. No. The C=C becomes a triple bond so that each carbon can join two chains.
  2. No. The C=C opens to a single bond so each carbon can join the chain.
  3. Yes. The C=C bond is what holds the repeat units together along the polymer chain.
Show the answer

No. The C=C opens to a single bond so each carbon can join the chain.

One bond of C=C breaks so that each carbon can join the next unit. Keeping the double bond as well would give each carbon five bonds.

Check your understanding

Chloroethene is CH2=CHCl. Which describes two repeat units of its addition polymer?

  1. -CH2-CHCl-CH2-CHCl-: four carbons, all single bonds, Cl on alternate carbons
  2. -CH=CCl-CH=CCl-: four carbons, double bonds kept, Cl on alternate carbons
  3. -CHCl-CHCl-CH2-CH2-: four carbons, all single bonds, Cl atoms side by side
Show the answer

-CH2-CHCl-CH2-CHCl-: four carbons, all single bonds, Cl on alternate carbons

Each C=C opens and the units join head to tail. Show a continuation bond at each end. The polymer is poly(chloroethene), also called PVC.

Check your understanding

A polymer has the repeat unit [-CF2-CF2-]n. What is its monomer?

  1. CF2=CF2
  2. CHF=CHF
  3. CF3-CF3
  4. CF2=CF-CF3
Show the answer

CF2=CF2

Remove the bonds to the next units and put back the C=C double bond. Each carbon keeps its two F atoms.

Exam-style question

Ethene is the monomer of poly(ethene).
(a) Name the type of polymerisation, and describe what happens to the ethene molecules. [2]
(b) State one use of poly(ethene). [1] [3]

Saved on this browser only. Anyone using this browser can see it.

05

Evaluate plastic use and recycling

Compare what happens to the molecules and to the wider system.

Many plastics are non-biodegradable: natural biological processes do not break them down readily. Persistent waste can harm wildlife through ingestion or entanglement, accumulate in habitats and fragment into small pieces. Burning plastics releases carbon dioxide and, depending on the plastic and conditions, other pollutants. Disposal shifts a problem unless its consequences are considered.

Two recycling routes
RouteWhat happensTrade-off
Physical recyclingSort and clean plastic, cut it into pieces, then melt it into pellets; poly(ethene) is an exampleRetains polymer molecules but mixed materials or contamination can reduce product quality
Chemical recycling by crackingBreak plastic molecules into smaller hydrocarbons that can be used as fuelCan process molecules differently, but requires energy; burning the fuel still releases carbon dioxide
Evaluate a proposed recycling system
DimensionQuestions that matter
SocialIs collection accessible? Are sorting instructions understandable? Are workers and nearby communities affected?
EconomicWhat do collection, transport, sorting and processing cost? Is there a market for the recovered material?
EnvironmentalHow much energy, transport and virgin resource use are avoided or added? What emissions and unrecovered waste remain?

Worked exampleCompare two claims

One plan melts clean separated poly(ethene) locally; another ships mixed plastic far away for cracking. Is either always better?

Try it first. Then show the worked stepsHide the worked steps
  1. The first may use less processing but depends on clean sorted input and a useful output market.
  2. The second may accept different waste but adds transport and cracking energy.
  3. Compare actual quantities, energy sources, yields and avoided virgin production.
Answer

A justified decision uses evidence across the whole process, rather than assuming the word recycling guarantees a lower impact.

Check your understanding

Does melting used poly(ethene) into pellets turn it back into ethene?

  1. Yes. Heating breaks the polymer chains back into ethene molecules.
  2. No. Melting only changes its shape; the long polymer chains remain intact.
  3. No. Melting turns it into a different polymer, poly(propene), with shorter chains.
Show the answer

No. Melting only changes its shape; the long polymer chains remain intact.

Mechanical recycling is a physical change. Getting the monomer back needs a chemical process that breaks the chain.

Quick revision

Revisit the essentials, then return to an explanation when you need it.

Exam definitions: learn these in mark-scheme words
TermDefinition to write
HydrocarbonA compound made of carbon and hydrogen only.
Homologous seriesA family of compounds with the same general formula and functional group, similar chemical properties, and a gradual change in physical properties as the molecules get larger. Successive members differ by CH2.
Saturated hydrocarbonA hydrocarbon with only single bonds between carbon atoms.
Unsaturated hydrocarbonA hydrocarbon with at least one carbon-carbon double bond.
CrackingThe breaking down of large hydrocarbon molecules into smaller, more useful molecules, using heat and a catalyst.
MonomerA small molecule that can join with many others to form a polymer.
PolymerA very large molecule built up from many small units (monomers).
Addition polymerisationMany unsaturated monomer molecules join together to form a polymer, with no other product formed.
PolyunsaturatedDescribes food molecules (fats and oils) that contain many carbon-carbon double bonds.
Core reaction connections
  1. Alkane

    Combustion; chlorine substitution under UV; larger molecules can crack.

  2. Alkene

    Bromine/hydrogen addition and addition polymerisation.

  3. Polymer

    Match the repeat unit to its monomer; distinguish physical and chemical recycling.

Scope

Learning outcomes

8. Organic Chemistry (K223 / K225). Use the outcome map to find the explanation for a particular syllabus requirement.

See the learning outcome map

  1. 8.1(a) Identify non-renewable fuel sources

    • Natural gas mainly methane
    • Crude oil

    Fuels, fractions and bioethanol

  2. 8.1(b) Explain crude-oil fractionation

    • Hydrocarbon mixture
    • Fractions
    • Competing fuel and chemical feedstock uses

    Fuels, fractions and bioethanol

  3. 8.1(c) Recognise renewable biofuel

    • Bioethanol from sugarcane

    Fuels, fractions and bioethanol

  4. 8.1(d) Compare carbon impacts of fuels

    • Plant-growth uptake offsets burning emissions
    • Compare fossil-carbon release
    • Sustainability depends on wider inputs

    Fuels, fractions and bioethanol

  5. 8.2(a) Describe homologous series

    • General formula
    • Similar chemistry
    • Gradual melting/boiling/viscosity change with size/mass

    Alkanes: build a valid carbon skeletonFuels, fractions and bioethanol

  6. 8.2(b) Describe alkanes

    • Saturated hydrocarbons
    • CnH2n+2

    Alkanes: build a valid carbon skeleton

  7. 8.2(d) Describe alkane reactions

    • Methane combustion
    • Chlorine substitution with UV
    • Generally unreactive otherwise

    Alkanes: build a valid carbon skeleton

  8. 8.2(e) Describe alkenes

    • Unsaturated hydrocarbons
    • CnH2n

    Alkenes: a double bond creates new reactions

  9. 8.2(g) Explain cracking

    • Alkenes and hydrogen products
    • Demand for smaller refinery molecules
    • Heating/catalyst conditions

    Alkenes: a double bond creates new reactionsFuels, fractions and bioethanol

  10. 8.2(h) Distinguish saturation

    • Molecular structure
    • Aqueous bromine test

    Alkenes: a double bond creates new reactions

  11. 8.2(j) Explain polyunsaturated food molecules

    • More than one C=C

    Alkenes: a double bond creates new reactions

  12. 8.2(k) Explain margarine manufacture

    • Hydrogen addition to vegetable oils
    • Solid product
    • Nickel catalyst and heat

    Alkenes: a double bond creates new reactions

  13. 8.2(c) Draw and name alkanes

    • Unbranched C1-C3
    • Methane to propane

    Alkanes: build a valid carbon skeleton

  14. 8.2(f) Draw and name alkenes

    • Unbranched C2-C3
    • Ethene and propene

    Alkenes: a double bond creates new reactions

  15. 8.2(i) Describe ethene reactions

    • Combustion
    • Polymerisation
    • Bromine and hydrogen addition
    • Essential conditions

    Alkenes: a double bond creates new reactionsAddition polymers: open the double bond, keep the substituents

  16. 8.3(a) Describe polymers and monomers

    • Large molecules from small units
    • Different monomers give different polymers

    Addition polymers: open the double bond, keep the substituents

  17. 8.3(b) Explain poly(ethene) formation

    • Addition polymerisation of ethene

    Addition polymers: open the double bond, keep the substituents

  18. 8.3(c) Identify poly(ethene) uses

    • Plastic bags
    • Clingfilm

    Addition polymers: open the double bond, keep the substituents

  19. 8.3(d) Deduce addition-polymer structures

    • Monomer to repeat unit
    • Repeat unit to monomer

    Addition polymers: open the double bond, keep the substituents

  20. 8.3(e) Explain plastic pollution

    • Non-biodegradability
    • Disposal impacts

    Evaluate plastic use and recycling

  21. 8.3(f) Compare recycling routes

    • Physical: poly(ethene) melted into pellets
    • Chemical: cracking into fuel

    Evaluate plastic use and recycling

  22. 8.3(g) Evaluate recycling issues

    • Social
    • Economic
    • Environmental

    Evaluate plastic use and recycling