Chem AO3 U1 research task

What is the general formula for alkanes, and how does octane fit into this formula?

Alkanes are saturated hydrocarbons.

“Saturated” means:

• all carbon-carbon bonds are single bonds

n = number of carbon atoms

Octane has:

• 8 carbon atoms

Substitute n=8n = 8n=8:

so

C8H18

2. Explain the concept of a homologous series and provide examples of alkanes that are part of this series. why do the physical properties change?

A homologous series is a family of organic compounds with:

• the same functional group

• similar chemical properties

• the same general formula

• gradual changes in physical properties

• each successive member differs by CH₂

Why Physical Properties Change

As chain length increases:

• molecular mass increases

• intermolecular forces become stronger

Therefore:

• boiling point increases

• melting point increases

Why is crude oil considered a non-renewable resource? and why does this matter?Why This Matters

Heavy reliance on crude oil leads to:

Crude oil is considered non-renewable because:

• it takes millions of years to form

• it cannot be replaced on a human timescale

• humans consume it much faster than it forms naturally

Once crude oil reserves are depleted:

• they cannot realistically be replenished

Why This Matters

Heavy reliance on crude oil leads to:

• resource depletion

• energy insecurity

• environmental damage

• greenhouse gas emissions

This is why scientists investigate:

• renewable fuels

• circular economy strategies

• sustainable chemistry

Describe the process by which crude oil is formed.

formed from the marines of ancient marine organisms that were buried under layers of sediment and subjected to heat and pressure over millions of years.

Converts organic material into hydrocarbons and is exracted and refined for fules

What is the significance of the octane rating in gasoline?

The octane rating measures a fuel’s resistance to “knocking” during combustion.

What is Knocking?

Knocking occurs when fuel combusts unevenly inside an engine.

This causes:

• reduced efficiency

• possible engine damage

What do higher octane rating mean?

• smoother combustion

• better engine performance

• greater resistance to premature ignition

Premium fuels therefore have higher octane ratings.

Write the balanced chemical equation for the combustion of octane.

Complete combustion occurs when there is excess oxygen.

Products are:

• carbon dioxide

• water

7. Discuss the environmental impact of burning octane as a fuel.

Greenhouse Gas Emissions

Combustion produces:

• carbon dioxide

CO₂ is a greenhouse gas that contributes to:

• global warming

• climate change and air pollution

Greenhouse gases trap infrared radiation in Earth’s atmosphere. which leads to?

• ising global temperatures

• altered weather patterns

• melting ice caps

• sea level rise

How can the principles of a circular economy be applied to the use of octane and other fossil fuels?

Circular Economy Definition

A circular economy aims to:

• minimise waste

• maximise reuse of resources

• keep materials circulating as long as possible

This contrasts with a linear economy:

take → make → dispose

Applying Circular Economy Principles to octane and other fossil fuels

Applying Circular Economy Principles 1. Improve Fuel Efficiency

Using less fuel reduces:

• emissions

• resource depletion

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2. Carbon Capture and Storage (CCS)

CO₂ from combustion can be:

• captured

• stored underground

• reused industrially

This reduces atmospheric emissions.

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3. Recycling Materials

Petroleum-based plastics can be:

• mechanically recycled

• chemically recycled

reducing demand for new crude oil extraction.

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4. Transition to Renewable Alternatives

Using:

• bioethanol

• biodiesel

• renewable electricity

reduces reliance on fossil fuels.

What is the general formula for alcohols, and how does ethanol fit into this formula?

R represents an alkyl group

Why is bioethanol considered renewable?

Bioethanol is renewable because it is produced from biomass:

• corn

• sugarcane

• crops

Plants can be regrown within short timescales.

Unlike fossil fuels:

• it does not require millions of years to form.

Carbon Cycle Link

Plants absorb atmospheric CO₂ during photosynthesis.

When bioethanol burns:

• CO₂ returns to atmosphere

This can make bioethanol closer to carbon-neutral.

Describe the process by which bioethanol is produced from biomass.

Step 1 — Biomass Contains Sugars/Starch

Examples:

• sugarcane

• corn

• Step 2 — Fermentation

  Yeast enzymes break down sugars in plants

Products:

• ethanol

• carbon dioxide

tep 3 — Distillation

Ethanol is purified from the fermentation mixture.

What is the significance of octane rating in bioethanol fuel?

Bioethanol has a high octane rating.

This means:

• good resistance to knocking

• smoother combustion

• efficient engine performance

This makes ethanol useful in petrol blends.

Discuss the + environmental impact of burning bioethanol.

• enewable

• lower net CO₂ emissions

• cleaner combustion

• fewer pollutants

Discuss the - environmental impact of burning bioethanol.

Disadvantages

• still emits CO₂

• agricultural land required

• possible deforestation

• fertiliser use may damage ecosystems

8. Circular economy and bioethanol

Bioethanol supports a circular economy because:

• produced from renewable biomass

• agricultural waste can be reused

• reduces fossil fuel dependence

Advanced biofuels can also use:

• waste biomass

• crop residues

which reduces waste generation.

What is the general structure of a biodiesel molecule?

Biodiesel molecules are esters.

long hydrocarbon chains

Describe step 1 in biodiesel production.

Hydrolysis

Triglycerides react with water.

• glycerol

• fatty acids

Triglycerides

the most common type of fat in your body

Transesterification / Condensation

Fatty acids react with methanol.

Products:

• biodiesel

• water

Catalyst:

• NaOH or KOH

Why is biodiesel renewable?

Because feedstocks can be replenished:

• vegetable oils

• animal fats

• used cooking oil

Plants regrow rapidly compared to fossil fuels.

Environmental benefits of biodiesel

Lower Emissions

Produces less:

• particulate matter

• carbon monoxide

• sulfur compounds

Biodegradable

Breaks down more easily than petroleum diesel.

7. Biodiesel and circular economy

Excellent circular economy example because:

• waste cooking oils are reused

• waste converted into useful fuel

• fewer materials discarded

• lower fossil fuel dependence

Advantages in engines and emissions

Better Lubricity

Reduces engine wear.

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Cleaner Combustion

Lower toxic emissions.