[Sophomore Biology: Organic Molecules Menu]


Water makes up about 70% of the mass of your body.


IMPORTANT PROPERTIES of WATER:

1. UNIVERSAL SOLVENT.- water dissolves many substances

2. SURFACE TENSION

A. COHESIVE: water molecules show attractions to each other. Allows insects to walk on water.

B. ADHESIVE: water molecules show attractions to other substances. Allows water to climb veins of tall trees.

3. HIGH BOILING POINT: Good insulator-Much energy is needed to raise or cool body temperature.

4. GOOD COOLANT: Evaporation takes energy from skin, cooling it.

5. SOLID FORM (ICE) IS LESS DENSE THAN LIQUID FORM, SO ICE FLOATS. THE ICE CAN THEN ACT AS AN INSULATOR.

6. pH: H2O breaks into H+ (hydrogen ions) and OH- (hydroxide) ions.

H2O ----> H+ + OH-

A. ACID: more H+ ions (pH 0-7)

B. BASE: more OH- ions (pH 7-14)

C. NEUTRAL: H+ = OH- (pH =7)

D. BODY FLUIDS: pH = 7.4


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