Why is water so important to life?

1. Why is water so important to life?

2. Extraordinary Properties of Water • Cohesion • Water molecules stick together • Surface tension • Adhesion • Water molecules cling to other solids • capillarity

3. High Specific Heat Amount of heat that must be absorbed for 1g to change 1o C for water = 1.00 cal/g/oC Sp Heat of common liquids Liquid SpHt (cal/g/oC) Ammonia 1.23 Water 1.00 Eth alc 0.60 Acetone 0.53 Olive oil 0.47 Mercury 0.03 Extraordinary Properties of Water

4. High Heat of Vaporization (change from liquid to gas) Quantity of heat a liquid must absorb for 1g to be converted to the gas state for water = 576 cal/g Ht of Vap of some liquids Liquid Ht Vap (cal/g) Water at 37C 576 Ammonia 302 Eth alcohol 237 Acetone 125 Mercury 59 Extraordinary Properties of Water

5. Extraordinary Properties of Water • Water Expands when freezing • Ice Floats! • Water is most dense at 4oC, and expands just a bit to form ice crystals

6. Extraordinary Properties of Water • Water is a versatile solvent • Ionic compounds dissolve in water • Covalent compounds rich in O or N dissolve in water

7. Extraordinary Properties of Water • Adhesion and Cohesion • High Specific Heat • High Heat of Vaporization • Expands when freezing • Versatile Solvent

8. How does water do all this?What allows water to facilitate life at the cellular and global level?

10. Hydrogen Bonds • A weak force of attraction between the H on one molecule and a highly electronegative atom on another molecule

11. Extraordinary Properties of Water • Versatile Solvent-------due to polarity • Adhesion and Cohesion---due to H bonds • High Specific Heat --------due to H bonds • High Heat of Vap. ---------due to H bonds • Expands when freezing ---due to H bonds

12. Ahh, water!