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2.2 Water

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Description

Nature of science:
Use theories to explain natural phenomena—the theory that hydrogen bonds form between water molecules explains the properties of water. (2.2)
Understandings:
  • Water molecules are polar and hydrogen bonds form between them.
  • Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water.
  • Substances can be hydrophilic or hydrophobic.
Applications and skills:
  • Application: Comparison of the thermal properties of water with those of methane.
  • Application: Use of water as a coolant in sweat.
  • Application: Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water.
Guidance:
  • Students should know at least one example of a benefit to living organisms of each property of water.
  • Transparency of water and maximum density at 4°C do not need to be included.
  • Comparison of the thermal properties of water and methane assists in the understanding of the significance of hydrogen bonding in water.
 International-mindedness:
  • There are challenges for the increasing human population in sharing water resources equitably for drinking and irrigation, electricity generation and a range of industrial and domestic processes.
Theory of knowledge:
  • Claims about the “memory of water” have been categorized as pseudoscientific. What are the criteria that can be used to distinguish scientific claims from pseudoscientific claims?
Utilization:
Syllabus and cross-curricular links:
Biology
Topic 4.3 Carbon cycling
Topic 4.4 Climate change
Physics
Topic 3.1 Thermal concepts

Aims:
  • Aim 6: Probes can be used to determine the effect of different factors likely to influence cooling with water.

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Sub sections and their related questions

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