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14.1 Finite and Renewable Resources

GCSE Chemistry · AQA · Chapter 14: The Earth's Resources

A free GCSE Chemistry lesson for AQA (8462) from OBA School: how we use Earth’s resources, the difference between finite and renewable resources, and sustainable development. Watch the video, read the explanation and worked examples, then try the revision questions. You can work through the full lesson, with every video, practice quizzes and printable worksheets with mark schemes, in our free online course.

What you will learn

  • State what humans use Earth’s resources for, and how agriculture and synthetic products add to natural resources
  • Distinguish between finite and renewable resources, with examples
  • Explain what sustainable development means and the part chemistry plays in it
  • Interpret data about resources, including using orders of magnitude and calculating how long reserves will last

Key words

  • Natural resource: Something found in or on Earth that people use, e.g. wood, cotton, crude oil, metal ores.
  • Finite resource: A resource that will run out, because it is used much faster than it forms. Also called non-renewable.
  • Renewable resource: A resource that can be replaced at the same rate as it is used, e.g. timber from managed forests.
  • Synthetic product: A material made by chemical reactions to replace or improve a natural one, e.g. polyester instead of wool.
  • Sustainable development: Development that meets the needs of people today without stopping future generations meeting their own needs.
  • Reserves: The amount of a resource known to exist that can be extracted with current technology.

Using Earth’s resources

Humans use Earth’s resources to provide warmth, shelter, food and transport. Many products come straight from nature, but chemists help in two ways:

  • Agriculture adds to natural resources. Fertilisers, pesticides and better crop varieties mean much more food can be grown on the same land.
  • Synthetic products replace or improve natural ones. Polyester and nylon replace or blend with cotton and wool; synthetic rubber replaces natural rubber; plastics replace wood, glass and metal in many uses.
  • Warmth; Natural resource wool, cotton, wood for burning; Synthetic or improved product polyester fleece, nylon; natural gas heating
  • Shelter; Natural resource timber, stone, clay; Synthetic or improved product bricks, cement, steel, plastic window frames
  • Food; Natural resource crops and animals; Synthetic or improved product fertilisers and pesticides that raise crop yields
  • Transport; Natural resource crude oil (fuels); Synthetic or improved product petrol and diesel from refining; biofuels; synthetic rubber tyres

Finite and renewable resources

Key fact: A resource is only renewable if it is managed. Timber is renewable when new trees are planted to replace the ones cut down. Cutting down a rainforest faster than it regrows is not sustainable.

Switching to renewable raw materials

Industry is trying to replace finite raw materials with renewable ones wherever it can. A good example is the plastic poly(ethene). Its monomer, ethene, is usually made by cracking alkanes from crude oil. But ethene can also be made from ethanol, and ethanol can be made by fermenting sugar from a crop. The plastic made at the end is exactly the same.

  • A crop can be grown again next year, so the sugar route is renewable and more sustainable – as long as land, water and energy are used carefully.
  • Some power stations burn wood pellets instead of coal. This only counts as renewable if new trees are planted to replace the ones that are cut down.
  • Biofuels such as bioethanol (made from crops) can replace some petrol made from crude oil.

Exam tip: Asked “finite or renewable?” about a product? Look at the raw material it was made from, not the product itself. Poly(ethene) from crude oil uses a finite resource; poly(ethene) from sugar cane uses a renewable one.

Sustainable development and the role of chemistry

Sustainable development meets the needs of current generations without compromising the ability of future generations to meet their own needs. Chemistry helps by:

  • developing catalysts and new processes that use less energy and fewer raw materials;
  • designing products that can be recycled, and processes that make less waste (high atom economy);
  • making new materials from renewable sources (e.g. plant-based plastics, biofuels);
  • finding ways to extract metals from low-grade ores and waste (see 14.4).

Interpreting data about resources

You may be given data about reserves and how fast a resource is used. Divide the reserves by the rate of use to estimate how long the resource will last.

Worked example: how long will reserves last?

Known reserves of metal ore P = 7.2 × 10⁸ tonnes. Use = 1.8 × 10⁷ tonnes per year.
years = reserves ÷ use per year = 7.2 × 10⁸ ÷ 1.8 × 10⁷ = 40

Answer: about 40 years at the current rate

Worked example: orders of magnitude

Reserves of mineral R are 5 × 10⁹ tonnes. Reserves of ore Q are 3 × 10⁷ tonnes.
10⁹ ÷ 10⁷ = 10², so reserves of R are about two orders of magnitude (roughly 100 times) bigger.

Answer: two orders of magnitude

Exam tip: Estimates of “years left” are uncertain, so they are best given only as an order of magnitude (tens, hundreds or thousands of years). New reserves may be found, new technology can reach ores that were too costly, recycling can cut demand, and the rate of use may rise as populations grow. Different assumptions can change the answer by a factor of 10 or more.

Worked example: an order-of-magnitude estimate

A country has about 2 × 10⁹ tonnes of a mineral and uses about 8 × 10⁶ tonnes a year.
years ≈ 2 × 10⁹ ÷ 8 × 10⁶ = 250 years. 250 is between 100 and 1000, so the answer is “hundreds of years”.

Answer: of the order of 10² years

Common mistakes

  • Calling fresh water or wood “finite”. They are renewable if they are managed and not used faster than they are replaced.
  • Saying fossil fuels are renewable “because they are still forming”. They form over millions of years, far slower than we use them.
  • Defining sustainable development as “using renewable resources”. It means meeting today’s needs without harming future generations’ ability to meet theirs.
  • Dividing the wrong way round in “years left” calculations. Years = reserves ÷ use per year.

Revision questions

Try these, then check your answers below each one.

Question 1. Which is the best definition of sustainable development? (Choose from: Development that meets the needs of today without compromising the ability of future generations to meet their own needs, Using only renewable resources, Recycling every material that is used, Producing as much as possible as cheaply as possible.)

Answer: Development that meets the needs of today without compromising the ability of future generations to meet their own needs

Working: Sustainable development meets the needs of current generations without compromising the ability of future generations to meet their own needs.

Question 2. Known reserves of a metal ore are 6.0 × 10⁸ tonnes. The world uses 2.4 × 10⁷ tonnes a year. How many years will the reserves last at this rate?

Answer: 25 years

Working: 6.0 × 10⁸ ÷ 2.4 × 10⁷ = 25 years.

Question 3. True or false? Polyester clothing fibre is a synthetic product made from crude oil.

Answer: True

Working: True. Polyester is a synthetic fibre made from chemicals obtained from crude oil. It replaces or blends with natural fibres such as cotton and wool.

Related lessons

Continue in the full course

This lesson is section 14.1 (AGCCH1401) of our free GCSE Chemistry course for AQA. In the full course you get every video for this section, a self-marking practice quiz, a printable worksheet with a mark scheme, chapter tests, and your progress saved. Go to the full GCSE Chemistry course.

 

 

 

 

 

 

 

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