1. 2.2: Water What do you know about water? 5 min. discussion
What are the uses of water in the human body?

2. Experiment: Regulation of human body temperature through sweat production
Find details for this task on moodle

4. Polarity Covalent bonds BUT electrons are NOT equally shared
It is a POLAR covalent bond
Oxygen exerts a greater pull on electrons than Hydrogen
Therefore, electrons move closer to Oxygen
Oxygen = negative charge
Hydrogen = positive charge
Sometimes referred to as dipolarity

5. Hydrogen bonds The attraction between the water molecules
Technically NOT a bond – an attraction
Weak intermolecular force, BUT water molecules are very small  LOTS of H-bonds.
Moly mods? Build a tetrahedral structure? Each water molecule can form four hydrogen bonds
Important to remember: H-bonds are a theory, scientists cannot prove they exist. But, it has not been disproved, and the presence of H-bonds helps to explain the unique properties of water.

6. Solvent properties Water is an excellent solvent.
Forms hydrogen bonds with polar molecules.
Both positive and negative ions are able to dissolve.

7. Cohesive & Adhesive properties
Cohesion = when two of the same type of molecule bind together
Adhesion = two molecules, of different types bind together
Cohesion
Adhesion
Water transport in plants – suction force through xylem ‘pulls’ water molecules upwards. Cohesion insures water molecules do not separate.
Maintain moisture in the leaves of plants. Water molecules ‘stick’ to cellulose molecules to prevent water loss.

8. Thermal properties High specific heat capacity
A (relatively) large amount of energy is required to raise and lower the temperature of water. As a result, water is a (relatively) thermally stable environment.
High latent heat capacity
Latent heat of vaporization = amount of heat required to evaporate a liquid. In water (due to H-bonds) the amount of energy required is high, therefore evaporation has a cooling effect.

9. More thermal properties…
High boiling point
Water is liquid over a wide range of temperatures 0 – 100 degrees C. Most habitats are within this range.

10. D

11. Comparing the thermal properties of water and methane
Read orange box pg. 71. Write a summary paragraph.

12. Hydrophilic V’s Hydrophobic
Water ‘loving’
Substances are chemically attracted to water.
Polar substances.
Anything that dissolves in water.
Anything that adheres to water.
Water ‘fearing’
Insoluble in water (can dissolve into other substances.
Non-polar (uncharged) substances.
e.g. glucose, cellulose
All lipids
In water, hydrophobic substances will be attracted to each other (this is due to the water molecules surrounding the substance being more attracted to each other (forming hydrogen bonds) than they are to the hydrophobic/non polar substance. This ‘clumping’ together of non polar substances in water is known as hydrophobic interaction.

14. *this question is from the OLD syllabus

15. 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

16. Design an experiment to investigate the solubility of water

17. Thermal properties – water/methane comparison data