Crude Oil and Fuels

Year 9 Topic 3 – Crude Oil and Fuels

Outline of the Topic

  • 1. Crude Oil & Hydrocarbons

  • 2. Fractional Distillation of Crude Oil

  • 3. Combustion of Hydrocarbons/ Balancing Equations

  • 4. Incomplete Combustion

  • 5. Acid Rain

Key Concepts and Definitions

1. Crude Oil & Hydrocarbons

  • Hydrocarbon:

    • Definition: A hydrocarbon is a compound of hydrogen and carbon only.

  • Crude Oil:

    • Definition: Crude oil is described as a mixture of hydrocarbons, a fossil fuel made from remains of dead sea creatures and plants, compressed and heated underground over millions of years.

  • Non-Renewable Nature:

    • Crude oil is classified as non-renewable and finite, meaning it is being consumed faster than it can be replaced and there is a limited amount on Earth.

2. Fractional Distillation of Crude Oil

  • Fractional Distillation:

    • Definition: A separating method that relies on different boiling points of liquids in a mixture. It is the process used to separate crude oil into various ‘fractions’.

  • Fractions:

    • Description: These are materials collected from fractional distillation that contains molecules with similar boiling points.

2.1 Main Fractions and Their Uses:

  • Refinery Gases:

    • Uses: Domestic heating and cooking.

  • Gasoline (Petrol):

    • Uses: Used as fuel in cars.

  • Kerosene:

    • Uses: Used as fuel in aircraft.

  • Diesel:

    • Uses: Used as fuel in some cars and larger vehicles like trains.

  • Fuel Oil:

    • Uses: Used for large ships and in some power stations.

  • Bitumen:

    • Uses: Utilized to surface roads and roofs.

2.2 Properties of Fractions:

  • Trend in Properties: As the molecular chain length increases, the following trends are noted:

    • Color: Darker as molecular weight increases.

    • Boiling Point: Higher for longer chains (more energy needed due to stronger intermolecular forces).

    • Viscosity: More viscous as molecular weight increases.

3. Combustion of Hydrocarbons and Balancing Equations

  • Definition of Fuel:

    • A fuel is defined as a substance that releases heat energy when burned.

  • Types of Combustion:

    • Complete Combustion: Occurs in the presence of ample oxygen, resulting in carbon dioxide and water.

      • Word Equation:
        Hydrocarbon + sufficient Oxygen → Carbon Carbon + Water + Energy

    • Incomplete Combustion: Happens when oxygen is limited, producing carbon monoxide (CO) and potentially soot.

      • Word Equation:
        Hydrocarbon + Insufficient Oxygen → Carbon Monoxide + Carbon + Water

  • Chemical Reaction Characteristics:

    • Combustion is an exothermic reaction, releasing heat and light.

    • The fire triangle comprises heat, oxygen, and fuel. Without one, combustion cannot occur.

  • Balancing Chemical Equations: Rules include:

    1. Don't change the formulas.

    2. Count all atoms for reactants and products.

    3. Add coefficients only in front of formulas.

    4. Balance oxygen last in combustion reactions.

4. Incomplete Combustion

  • Consequences of Incomplete Combustion:

    • Insufficient oxygen leads to carbon monoxide production, which is toxic.

    • Carbon monoxide binds with red blood cells, reducing their capacity to transport oxygen, potentially leading to fainting or death.

  • Common Indicators:

    • Occurs commonly in faulty appliances.

5. Acid Rain

  • Formation of Acid Rain:

    • Sulfur contained in fuels reacts during combustion to form sulfur dioxide (SO2), which combines with water to create dilute sulfuric acid.

    • Nitrogen oxides (NOx) also form when fossil fuels burn, leading to the production of nitric acid.

  • Environmental Impact:

    • Acid rain can kill aquatic life, damage plants, and corrode buildings and architecture.

Connection to Global Issues

  • The combustion of fossil fuels contributes not only to acid rain but also to global warming due to increased levels of CO2, a greenhouse gas.

  • Global warming/Climate Change consequences:

    • Increased frequency and severity of severe weather events

    • Loss of habitats for animals

    • Extinction of animals

  • Balancing Chemical Equations: Rules include: 1. Don't change the formulas. 2. Count all atoms for reactants and products. 3. Add coefficients only in front of formulas. 4. Balance oxygen last in combustion reactions.

Review Questions

  • Thinking Questions on Fractional Distillation:

    1. What change of state occurs when crude oil is initially heated? (Boiling)

    2. What is distinct about bitumen? (It can behave as both a liquid and solid; doesn't boil into a gas)

    3. How do boiling points change with carbon atom number? (They decrease with fewer carbon atoms)

    4. Why are approximate carbon numbers provided? (Each fraction is a mixture of hydrocarbons)

    5. How does color change in a fractionating column? (Color lightens upwards)

    6. What happens to viscosity as you ascend the column? (Viscosity decreases, making them easier to pour)

Conclusion

The study of crude oil and its derivatives encompasses a multitude of areas including chemistry, environmental science, and energy production, highlighting both the usefulness and the consequential ecological impacts of fossil fuel usage.