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)

• 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.

• 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.