Bio ch 3

Why is water polar?

Oxygen is more electronegative than hydrogen and the electrons of the polar bonds spend more time near oxygen thus, making oxygen more negativity charged and hydrogen more positively charged

Why is water's polarity significant?

contributes to the fitness of the Earth including other water properties like its cohesion, ability to stabilize temperature, expansion upon freezing, as well as its versatility as a solvent

Cohesion

holding a substance together

Adhesion

clinging of a substance to another

Capillary action

the attraction of the surface of a liquid to the surface of a solid, which causes the liquid to rise or fall

Surface Tension

A measure of how difficult it is to break/stretch a surface

Kinetic Energy

energy of motion

Heat

total kinetic energy due to molecular motion

Calorie

amount of heat it takes to move 1 gram of substance 1 degree Celsius higher

Temperature

intensity of heat due to average kinetic energy

Specific heat

amount of heat needed to be absorbed /lost to change the temperature by 1 degree Celsius

What is the specific heat of water?

1 calorie/1 gram/I degree Celsius

How does high specific heat of water affect temperature in large bodies of water?

can absorb huge amount of heat at night while gradual cooling can warm the air

Evaporative cooling

remains of a liquid cool down

vaporization

amount of heat needed to turn liquid into gas

evaporation

process of liquid becoming gas

Result of water's high heat of vaporization?

stability of temperatures in lakes and ponds

What happens to the density of water as temperature decreases?

because of hydrogen bonding, at temperatures above 4 degree celsius , water behaves like other liquids (expanding as it warms, contracting as it cools), molecules began to freeze when molecules no longer move vigorously to break hydrogen bonds. At O degree celsius, the water is locked in crystalline lattice and keeps hydrogen bonds at "arm's length", at temperatures above 4 degrees Celsius, bonds are free to slip close

How does the density of water contribute to aquatic life?

if ice sank, ponds/oceans/lakes would freeze solid, killing the life (during the summer only top would thaw) instead the floating ice insulates liquid water from below preventing it from freezing and killing animals

solution

liquid completely homogeneous of two or more substances

solvent

dissolving agent

solute

substance dissolved

aqueous solution

water is solvent

solute

substance dissolved

aqueous solution

water is solvent

hydration shell

sphere of water molecules around dissolved ions

hydrophobic/philic substances

water loving/hating

molecular weight

sum of all atoms

mole

the molecular weightof a substance expressed in grams (6.02 x 10^23)

molarity

concentration measured by number of mols/liter of solution

hydrogen ion

H+

hydroxide ion

OH-

hydronium ion

H30+

acids

increase H+ concentration

bases

reduce H+ concentration

strong acids and bases

completely ionized when dissolved in water

weak acids and bases

only partly ionized in their solution

pH scale

measures concentration of H+ (scale from 1-14)

buffers

substance that minimizes changes in H+/OH- concentration

Extent of acid precipitation

presence of sulfur oxides/nitrogen oxides and gaseous compounds react with air and goes into lakes, oceans, and soil, affecting animal life