1. WATER & Its Unique Properties
H2O aka dihydrogen monoxide

2. Polar molecule – has a positive end and a negative end
What water looks like…

3. Special Characteristics
Density – water is less dense as a solid than as a liquid
Boiling and melting points – melts/freezes at 0°C and evaporates/condenses at 100°C
High Specific Heat Capacity – takes large amount of energy to change temperature 1 degree celcius
Special Characteristics

4. Strong intermolecular forces – hydrogen bonding, each water molecule can form four hydrogen bonds
Characteristics….

5. Surface Tension – results from cohesion; molecules stick to each other
Capillary Action – results from adhesion; molecules stick to other surface like a straw
Characteristics….

6. Aka The Universal Solvent
Water is known as a “universal solvent” because it can dissolve many substances.
Water dissolves substances by surrounding charged particles and “pulling” them into solution. Any substance that carries a net electrical charge can dissolve in water.
Aka The Universal Solvent

8. Water molecules contract until they reach 4 oC, then they expand as the ice crystals form until they are solid. Solid water (ice) is less dense than liquid water; hence it floats!
Why does ice float?

9. Since water has the ability to dissolve many substances water may contain a variety of materials.
The main components that are in water are:
Dissolved and undissolved solids like salt, oil, calcium
Particulate matter such as clay
Living materials such as algae or bacteria
What’s in the Water?

10. Water Quality- How clean is it?
Most clean water supplies contain a mixture of the materials just described.
Some materials like phosphates for example are needed for plants and aquatic organisms to survive.
However, if too high of a concentration builds up it can cause disastrous affects to the ecosystem.
Water Quality- How clean is it?

11. Water Quality Indicators
Temperature pH
Dissolved oxygen
Nutrients
Dissolved solids
Turbidity
Bacterial Count
Water Quality Indicators