This topic explores the key concepts of water as they relate to:
- functional uses of water
- properties of water
- solutes, solvents and solutions
- solubility and concentration
- reactions in solution.
Key concepts of water:
The activities in this topic are designed to explore the following key concepts:
- Water is an essential component of all living things.
- Water is a good solvent.
- Water exists as molecules of H2O.
- The water molecule is polar in structure; this concept explains many of water's properties.
- Water has relatively high melting and boiling points.
- Water expands on freezing. Ice is less dense than liquid water.
- Large amounts of energy (latent heat) are required for a change of state of water.
Students' alternative conceptions of water
Research into students' ideas about this topic has identified the following non-scientific conceptions:
- Water is something different from H2O molecules.
- Water molecules have different sizes and shapes.
- There is no space between water molecules in ice.
- Water vapour molecules weigh less than ice molecules.
- The 'skin' of a water drop or water surface is a different kind of water.
- Oil doesn't mix with water because oil and water molecules repel each other.
- Water molecules are largest and heaviest when in the solid phase.
- Water molecules can be seen with an optical microscope.
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