Properties+of+Water

=Properties of water (SBI3U)= 10/9/10 Without water there would be no life. Why?

1. Water is **polar** Oxygen (O) end of molecule is slightly negative Hydrogen (H) end of molecule is slightly positive
 * Because...**

Therefore water forms hydrogen bonds (H-bonds)

However, polar water molecules ALSO result in hydrophobic (water fearing) and hydrophilic (water loving) interactions with other chemicals.

2. Unique property of water: **cohesion** Because of the H-bonds, water molecules stick together, thus, raising melting point and boiling point of water molecules compared to comparably sized molecules.

3. **High specific heat** -- because of cohesion, water requires a lot of heat energy to change temperature Therefore, it moderates Earth's climate making it habitable. The Earth is not too hot, not too cold; it's "just right".

4. **Density** -- frozen water is less dense than liquid water. Therefore frozen water (ice) floats and keeps heat trapped underneath it keeping the water underneath it liquid. This is a good habitat for organisms to survive the cold of winter.

5. Water is a **solvent**. Therefore it dissolves many compounds and can transport them.

6. **Dissociation** -- H and O separate and give us... i) pH (H + and OH - ions) ii) good environment for chemical reactions (technically item i is actually part of item ii)