1. Water, Water Everywhere! Textbook Chapter (2.3)
Essential Questions:
What are the properties of Water?
What are Mixtures, Solutions and Suspensions?
Why is water important for living things?
What is the pH scale?

2. Introduction to Water
Consists of 1 Oxygen atom and 2 Hydrogen atoms per 1 water molecule.
How is water bonded?
Covalent Bonds
Carries substances via Osmosis.
Serves as material transportation
Blood, plant sap
Water makes up 70-95% of organisms.
Because of its bonding it can hold large molecules like proteins together.
Cycles through the kidneys and eliminated out of the body

3. Five Major Properties of Water
Water is liquid at room temperature, boiling point is high at 100° C; low molecular weight molecules are usually gaseous.
Water resists temperature change (insulator)‏
Has three phases: Solid (ice), liquid, gas (vapor)‏
Water has a high freezing point and ice is less dense than water. (Thus, ice floats in water.)
Water is the universal solvent for polar and ionic molecules (means it dissolves things)
Hydrophilic: means “water-loving”, molecules that interact with water, soluble in water
Hydrophobic: means “water-fearing”, insoluble in water
Polar: Means it has a slightly positive (+) end and a slightly negative (-) end.

4. Five Major Properties of Water
4. Water is sticky:
Why? Hydrogen bonds keep water together (polar areas attract)
Slightly negative (-) Oxygen end
is attracted to the slightly
positive (+) Hydrogen ends.
Cohesion: attraction of water to other water molecules.
Adhesion: attraction of water to other types of molecules.
Capillary Action: Can adhere creep up tubes.
Examples:
- From ground to tops of trees.
- The meniscus in a graduated cylinder.

5. Five Major Properties of Water
5. Water has high surface tension
water is more attracted to itself than to the air around it
Sticks together (+ and – attract.)
Your Mini-Lab today concerns determining factors that affect
Surface Tension!

6. Mixtures, Solutions & Suspensions
A mixture is a combination of substances where both substances keep their original properties.
Physically mixed, not chemically mixed.
Solution – one or more substances (solutes) are distributed evenly in another substance (solvent) (water)‏
The more solute in a solvent, the higher the concentration.
Organisms need to maintain a certain concentration for life processes, called homeostasis.
Suspensions – mixtures of water and non dissolved particles
Example: Blood
Signs of Dehydration

7. pH Scale HCl (acid) + NaOH (base)  H2O (water)+ NaCl (salt)‏
pH – a measure of how acidic or basic something is.
Use pH paper (litmus paper) to test
Acidic range is 0-6
Acids form H+ ions in water
Example: Lemon (2)‏
Neutral is 7
Example: Pure water and blood (7)‏
Basic range 8-14
Bases form OH- ions in water
Example: Ammonia (12)‏
Buffers – weak acids and weak bases that react with strong acids or bases to prevent sudden changes in pH.
Used to maintain homeostasis.
You can cause a Neutralization reaction by using an acid and a base combine to form water and a salt (ionic compound)‏
HCl (acid) + NaOH (base)  H2O (water)+ NaCl (salt)‏
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8. Homeostasis
The ability or tendency of an organism to maintain internal equilibrium, or balance, internally.

9. Fight Club Science: Neutralization Reaction
In the Movie, Fight Club, Brad Pitt’s Character puts a chemical burn (using Lye, pH of 13) on Edward Norton’s Character's wet hand.
Start at 1:16 on Video Clip from Fight Club:
What is Lye, an Acid, Base or Neutral substance?
Why would putting Water on this burn not help?
What is the pH of Water?
Why would Vinegar put out the burn?
What is the pH of Vinegar?
You need a weak acid to neutralize a strong base into a neutral substance and salt.
Base 7 3

10. Properties and biological roles of water