1. The Extraordinary Properties of Water

2. Water Molecule H 2 O made of atoms –2 Hydrogen & 1 Oxygen H H O

3. Water is Polar Oxygen negative”Oxygen “negative” Hydrogen positive”Hydrogen “positive” neutralWater is neutral p+ = e-

4. Hydrogen Bonds Exist Between Water Molecules One hydrogen bond is weak, but many hydrogen bonds are strongOne hydrogen bond is weak, but many hydrogen bonds are strong

5. What are the Properties of Water?

6. Properties of Water CohesionCohesion AdhesionAdhesion Heat CapacityHeat Capacity

7. Cohesion Attraction between molecules of the same substanceAttraction between molecules of the same substance Results in Surface tensionResults in Surface tension –a measure of the strength of water’s surface

8. Cohesion Helps insects walk across water

9. Adhesion Attraction between molecules of different substancesAttraction between molecules of different substances Results in “sticking” (hydrogen bonding) to other surfacesResults in “sticking” (hydrogen bonding) to other surfaces Capillary action-water molecules will “tow” each other along when in a thin glass tube.Capillary action-water molecules will “tow” each other along when in a thin glass tube. –transpiration process which plants and trees remove water from the soil, and paper towels soak up water.

10. Adhesion Form spheres & hold onto plant leaves Attach to a silken spider web

11. Heat Capacity.Water resists temperature change, both for heating and cooling. Water can absorb or release large amounts of heat energy with little change in actual temperature.Water can absorb or release large amounts of heat energy with little change in actual temperature.

12. Properties of Water… As a table group answer A-I with the property of water that applies to the phenomenon Be ready to justify your answers!

14. Homeostasis Ability to maintain a steady state despite changing conditionsAbility to maintain a steady state despite changing conditions Water is important to this process because:Water is important to this process because: a. Makes a good insulator b. Resists temperature change c. Universal solvent d. Coolant e. Ice protects against temperature extremes (insulates frozen lakes)

15. Solutions & Suspensions Water is usually part of a mixture.Water is usually part of a mixture. There are two types of mixtures:There are two types of mixtures: –Solutions –Suspensions

16. Solution Ionic compounds disperse as ions in waterIonic compounds disperse as ions in water Evenly distributedEvenly distributed SOLUTESOLUTE –Substance that is being dissolved SOLVENTSOLVENT –Substance into which the solute dissolves

17. Solution

18. Suspensions don’t dissolve but separateSubstances that don’t dissolve but separate into tiny pieces. Water keeps the pieces suspendedWater keeps the pieces suspended so they don’t settle out.

19. Acids, Bases and pH One water molecule in 550 million naturally dissociates into a Hydrogen Ion (H+) and a Hydroxide Ion (OH-) Hydrogen Ion Hydroxide Ion Acid Base Acid Base H 2 O  H + + OH -

20. The pH Scale concentration of H + ionsIndicates the concentration of H + ions 0 – 14Ranges from 0 – 14 7 is neutralpH of 7 is neutral 0 up to 7 is acidpH 0 up to 7 is acid … H + above 7 – 14 is bpH above 7 – 14 is basic… OH - 10XEach pH unit represents a factor of 10X change in concentration pH 3 is 10 x 10 x 10 (1000) stronger than a pH of 6pH 3 is 10 x 10 x 10 (1000) stronger than a pH of 6

21. Acids Strong Acids have a pH of 1-3Strong Acids have a pH of 1-3 Produce lots of H + ionsProduce lots of H + ions

22. Bases Strong Bases 11 to 14Strong Bases have a pH of 11 to 14 lots of OH - ionsContain lots of OH - ions and fewer H+ ions

23. Buffers Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH (neutralization).Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH (neutralization). Produced naturally by the body to maintain homeostasisProduced naturally by the body to maintain homeostasis Weak Acid Weak Base