1. The Chemistry of Water

2. Water Water, Water Everywhere If you have ever seen a photograph of Earth from space, you know that much of the planet is covered by water. Water makes life on Earth possible. If life as we know it exists on some other planet, water must be present to support that life.

3. Water 1. Working with a partner, make a list of ten things that have water in them. 2. Exchange your list for the list of another pair of students. Did your lists contain some of the same things? Did anything on the other list surprise you? 3. Did either list contain any living things?

4. Water Makes life possible Life on earth probably evolved in water Living cells are 70% to 90% water Water covers about 75% of the earth Only substance on earth that exists in each of the 3 physical states of matter Polar molecule held together by hydrogen bond

5. Hydrogen Bond Hydrogen bond Formed when a hydrogen atom covalently bonds to another atom The + charge of the H will attract to the – charge of the O Hydrogen Bonding

6. Properties of Water 1. Cohesion: Stick to itself force 2. Adhesion: Stick to other things force

7. Properties of Water 3. Capillary Action: Water rising through a small tube defying gravity *The smaller the tube the higher the water climbs*

8. Properties of Water *Above properties aide in the upward movement of water in plants

9. Water Properties Cont. 4. Surface Tension: Measure of how difficult it is to stretch or break the surface of a liquid. Water has a greater surface tension than most liquid

10. Ex] Small insects are able to walk on water

11. Water Properties Cont. 5. Expansion of water as it freezes  Becomes less dense  Prevents bodies of water from freezing solid from bottom up  Ice forms on surface releasing heat to the water below and insulating it.

12. Water Properties Cont. 6. High Specific Heat: Ability of water to absorb a lot of heat energy without having its temperature increase by very much Ex] moderates climates Ex] moderates climates BECAUSE OF WATER'S HIGH SPECIFIC HEAT CAPACITY, CITIES LOCATED NEXT TO LARGE BODIES OF WATER TEND TO STAY WARMER IN THE WINTER AND COOLER IN THE SUMMER. DURING THE EARLY SUMMER MONTHS, FOR INSTANCE, CHICAGO'S LAKEFRONT STAYS COOLER THAN AREAS FURTHER INLAND. THIS IS BECAUSE THE LAKE IS COOLED FROM THE WINTER'S COLD TEMPERATURES AND SNOW RUNOFF.

13. Water Properties Cont. 7. High Heat of Vaporization: Amount of energy needed to transform a liquid to a gas. Takes a lot of heat to evaporate just a little water EX] allows water to remain in smaller lakes and ponds in the summer

14. Water Properties Cont. 8. High heat of Fusion: Amount of energy taken from water to transform liquid to solid  Lakes and streams take longer to freeze allowing wildlife more time to adapt.

15. Mixtures Combination of substances in which the individual substances retain their own properties No chemical bonds A. Can be separated by physical means

16. Types of mixtures 1. Solution: Homogenous (same throughout) mixture of 2 or more substances in which one substance (the solute) dissolves in another substance (the solvent). A. Will not settle out B. Transparent Ex] salt water, sugar water, Kool-Aid

17. Types of mixtures 2. Suspension: Mixture with larger particles than in a solution, suspended in another medium. A. Will settle out B. Cloudy C. Particles may not be homogenous Ex.] Clay in water, Liquid “pink stuff” (amoxicillin)

18. Types of mixtures 3. Colloid: Have particles that are larger than a solution, but smaller than a suspension. Share characteristics of both solution & suspension. Have particles that are larger than a solution, but smaller than a suspension. Share characteristics of both solution & suspension. A. Do not settle out B. Usually cloudy Ex] Mayonnaise, milk, cytoplasm, paint, blood serum, Jell-O

19. Mixtures

20. Acids & Bases pH Measure of how acidic or how basic something is Regulator of every reaction in a living system

21. Acids  Taste sour  Forms H+ ions in solution  Recognized by the chemical formula (beginning with an H) Ex] HCl, HNO 3

22. Base  Bitter taste  Slippery feel  Forms OH- (hydroxide) ions in solution Ex] KOH, NaOH

23. pH Scale Oven cleaner Bleach Ammonia solution Soap Sea water Human blood Pure water Milk Normal rainfall Acid rain Tomato juice Lemon juice Stomach acid Neutral Increasingly Basic Increasingly Acidic

24. Acids & Bases Buffers: Minimize pH changes: absorb or release H+ ions Minimize pH changes: absorb or release H+ ionsSalts: Formed when acids & bases are mixed in solution The H+ ions combine with the OH- ions forming water. The salt is formed from the anion & cation that remain