Water A1.1

Polarity of Water

due to unequal sharing of electrons

Properties of water

1. Cohesion

2. Adhesion

3. Thermal conductor

4. Solvent

5. Specific heat capacity

Reactants must be dissolved to react, therefore medium of reaction

Transports nutrients around the body

Cohesion

Water sticking/attracted to nearby (hydrogen bonds) → transpiration stream

Surface tension

transport of water under tension in xylem and use of water surfaces as habitats due to surface tension

Adhesion

Water sticks to other polar/charged molecules through hydro. bonds
positive → oxygen

negative → hydrogen

capillary action in soil and in plant cell walls (cellulose)

Thermal conductivity

Good thermal conductor, takes heat away from individuals

Seals → large layer of blubber to keep warm

Ducks → feather with hydrophobic oil

specific heat capacity

energy required to raise temp of water by 1C

→ high specific heat capacity: retains its temperature, keeps temp stable and constant for the environment

→ absorb/release large amount of energy without experiencing significant temp change

Solvent

dissolve and surround other substances (ionic and polar)

Oxygen → sodium

Hydrogen → chloride

Pulls it apart

(allows chemical reactions to occur)

wide variety of hydrophilic molecules dissolve in water and most enzymes catalyze in aqueous solutions. functions of some molecules relies on hydrophobic and solvent properties

Physical properties of water

1. buoyancy

2. viscosity

buoyancy

upward force exerted by a fluid on an object immerse in a fluid

denser than air providing greater buoyancy (conserve energy, helps them float)

blubber offers more buoyancy (ringed seals) → less dense than muscles

viscosity

slower to flow (thicker), water is more difficult to flow

→ higher viscosity makes it harder for animals to move through

→ aquatic animals are streamlined to make it easier to move through water

black-throated loons: streamlined in water but in air wings are out for more air resistance

extraplanetary origin of water

1. water was not present on earth when the planet was formed → it was too hot and water vapor would’ve been blown away by solar winds

2. earth cooled down and water arrived as ice from asteroids (evaporated water gets trapped in the atnosphere and stays on earth due to gravity)

3. makes planet habitable, creation of the water cycle

goldilocks zone

planets in orbits of a star where it is not too hot/cold for liquid water to exist