Earth's Resources and Human Needs Revision Notes | GCSE AQA Higher Chemistry

1. Why Earth's Resources Matter

Every morning you wake up in a house built from Earth's materials, eat food grown in Earth's soil, and travel using energy from Earth's resources. But here's the problem: we're using these resources faster than Earth can replace them.

Humans depend on Earth's resources for four essential needs: warmth (heating fuel), shelter (building materials), food (agriculture), and transport (fuels and metals). Natural resources from the land, oceans and atmosphere provide the raw materials. Agriculture supplements what nature provides, while synthetic chemistry creates alternatives when natural supplies run short.

2. Finite vs Renewable Resources

The key difference is time. Renewable resources regenerate within human timescales - trees regrow in decades, water cycles continuously. Finite resources took millions of years to form. Once we burn all the oil or mine all the copper ore, it's gone forever.

3. Natural, Agricultural and Synthetic Products

Nature provides the starting point, but humans have learned to supplement and replace natural products. Here's how the three types compare:

Natural products come directly from the environment - cotton from plants, wool from sheep, timber from trees. Agricultural products are natural materials produced through farming - crops grown in larger quantities than nature alone would provide. Synthetic products are manufactured alternatives designed to replace natural materials.

Worked example: Comparing Clothing Materials

Compare cotton (natural), farmed cotton (agricultural), and polyester (synthetic) for making clothes.

1. Wild cotton: limited quantities, seasonal availability, variable quality — Nature provides small amounts when conditions are right
2. Farmed cotton: large-scale production, selective breeding for better fibres, year-round supply through global farming — Agriculture increases quantity and improves quality
3. Polyester: made from oil, consistent properties, water-resistant, cheaper to produce — Chemistry creates materials with designed properties
4. Cotton biodegrades but needs lots of water; polyester lasts longer but creates microplastic pollution — Each option has environmental costs and benefits

Answer: Agricultural cotton supplements natural cotton supply; synthetic polyester provides an alternative with different properties and environmental impacts.

4. Processing Earth's Resources

Raw materials from Earth rarely come ready to use. Finite resources from the Earth, oceans and atmosphere must be processed to provide energy and useful materials. This processing often requires significant energy input and can create environmental challenges.

Metal ores contain the metal mixed with rock and other compounds. We extract pure metals through processes like electrolysis or reaction with carbon. Crude oil gets refined into different fuels and chemical feedstocks. Even renewable resources need processing - timber becomes paper, crops become food products.

Worked example: Processing Iron Ore to Steel

Describe how iron ore (finite resource) becomes steel for construction.

1. Mine iron ore (mainly iron oxide, Fe₂O₃) from the ground — This depletes finite reserves of iron ore
2. Heat with carbon in a blast furnace: Fe₂O₃ + 3CO → 2Fe + 3CO₂ — Chemical reduction removes oxygen from the ore
3. Add controlled amounts of carbon and other elements to pure iron — Alloying improves strength and corrosion resistance
4. Roll, forge or cast steel into beams, sheets or other construction materials — Physical processing creates useful shapes

Answer: Iron ore (finite) → pure iron → steel alloy → construction materials through mining, chemical reduction, alloying and physical shaping.

5. Exam Technique and Common Mistakes

Resource questions test your ability to classify materials and explain sustainability. Examiners look for precise terminology and clear reasoning about environmental impacts.

Common exam mistakes: Calling renewable resources 'unlimited' (they can be overused), confusing natural with renewable (some natural resources like oil are finite), and forgetting that synthetic doesn't always mean worse (synthetic materials often have superior properties).

Exam precision note: In Earth's Resources and Human Needs - Using the Earth's resources and sustainable development - Using the Earth's resources and obtaining potable water, always identify the key chemical idea first, then link it to evidence, data, or an equation. A high-scoring GCSE answer names the particles involved, states what changes, and justifies the conclusion using correct scientific language. Where calculations are used, show each step with units and keep significant figures sensible. Finally, check that terminology matches AQA wording so your answer is unambiguous and mark-scheme friendly.

Sustainable development is about balancing present needs with the long-term availability of resources. Some Earth resources, such as metal ores and crude oil, are finite because new supplies form far too slowly for human use. Others, such as timber and crops, can be renewed if they are managed so that use does not exceed replacement.