Composition of Water (WJEC GCSE Chemistry)

Composition of Water

• We use water in many aspects of our everyday life:

  • Domestic uses: for drinking, cooking, gardening and general sanitation 

  • Agricultural uses: as a drink for animals and watering crops

  • Industrial uses: as a solvent, as a coolant and heated to make steam used to generate electricity

• Water is found in natural sources such as lakes, rivers and underground water sources (groundwater)

• A rock that stores water is known as an aquifer

• Water from natural sources may contain a variety of different substances including:

  • Dissolved oxygen

  • Dissolved carbon dioxide from rainwater (which lowers the pH of water)

  • Metal ions (E.g. Ca²⁺, K⁺, Na⁺, Mg²⁺)

  • Plastics

  • Sewage

  • Harmful microbes

  • Nitrates from fertilisers

  • Phosphates from fertilisers and detergents

• Some of these substances are classed as pollutants 

  • Pollutants can either be natural or man- made

  • Natural pollutants enter water sources when rain falls and washes them into lakes, rivers or groundwater

    • These include bacteria and viruses

  • Man made pollutants are a direct result of human activities

    • These include fertiliser, pesticides and household and industrial waste

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