Bio Chapter 3- Water And The Fitness Of The Environment

Front 1

what % of cells are water

Back 1

70-95%

Front 2

water molecules

Back 2

two hydrogen atoms form single polar covalent bonds with an oxygen atom.
Because oxygen is more electronegative than hydrogen, the region around the oxygen atom has a partial negative charge.
The regions near the two hydrogen atoms have a partial positive charge.
A water molecule is a polar molecule in which opposite ends of the molecule have opposite charges.

Front 3

hydrogen bonding in water molecules

Back 3

The slightly negative regions of one water molecule are attracted to the slightly positive regions of nearby water molecules, forming hydrogen bonds.
Each water molecule can form hydrogen bonds with up to four neighbors.
-- weak bonds
-- they last only a trillionth of a second because they break and reform with other molecules

Front 4

4 emergent properties of water that contribute to earth's fitness for life

Back 4

cohesion
moderation of temp
insulation of water by floating ice
solvent

Front 5

cohesion

Back 5

water molecules bond to each other with hydrogen bonds
this is what allows water olecules to pull each other up through the roots of plants

Front 6

adhesion

Back 6

clinging of one substance to another--- water adheres to the walls of the cells

Front 7

surface tension

Back 7

the force necessary to stretch or break the surface of a liquid
water has greater surface tension because of hydrogen bonds

Front 8

how does water moderate earth's temp?

Back 8

stabilizes air temperatures by absorbing heat from warmer air and releasing heat to cooler air.
Water can absorb or release relatively large amounts of heat with only a slight change in its own temperature.

Front 9

heat

Back 9

measure of total kinetic energy (atoms are moving) due to molecular motion in a body of matter

Front 10

temperature

Back 10

intensity of heat in a body of matter due to average kinetic energy of molecules

Front 11

calorie

Back 11

amount of heat energy necessary to raise the temperature of one g of water by 1°C.

Front 12

kilocalorie

Back 12

A kilocalorie is the amount of heat energy necessary to raise the temperature of 1000 g of water by 1°C.

Front 13

joule

Back 13

energy unit 0.239 cal

Front 14

specific heat of a substance

Back 14

amount of heat that needs to be absorbed for 1 g of substance to raise 1 degree celcius

Front 15

specific heat of water

Back 15

1 cal per gram per degree Celsius or 1 cal/g/°C.

higher than most which means it must absorb or lose more heat for its temp to change

Front 16

why is the specific heat of water high and why is this good for the earth

Back 16

it takes a lot of energy to break or form hydrogen bonds


A large body of water can absorb a large amount of heat from the sun in daytime during the summer and yet warm only a few degrees.
At night and during the winter, the warm water will warm cooler air.
Therefore, ocean temperatures and coastal land areas have more stable temperatures than inland areas.
Living things are made primarily of water. Consequently, they resist changes in temperature better than they would if composed of a liquid with a lower specific heat.

Front 17

vaporization/ evaporation

Back 17

occurs when the molecule moves fast enough to overcome the attraction of other molecules in the liquid.
Even in a low-temperature liquid (with low average kinetic energy), some molecules are moving fast enough to evaporate.
Heating a liquid increases the average kinetic energy and increases the rate of evaporation.

Front 18

heat of vaporization

Back 18

quantity of heat that a liquid must absorb for 1 g of it to be converted from liquid to gas.
Water has a relatively high heat of vaporization, requiring about 580 cal of heat to evaporate 1 g of water at room temperature.

Front 19

evaporative cooling

Back 19

hotter molecules evaporate making the ave kin energy of the ones behind lower aka cooler

Front 20

evaporation in organisms

Back 20

releases heat in sweat and cools organisms down

Front 21

what happens when water freezes

Back 21

when the temperature falls the molecules slow down and cant break the hydrogen bonds so they are held at arms length away from each other making it 10% less dense than at 4 degrees

Front 22

why is water's low density when it freezes good for earth?

Back 22

If ice sank, eventually all ponds, lakes, and even the ocean would freeze solid.
During the summer, only the upper few centimeters of the ocean would thaw.
Instead, the surface layer of ice insulates liquid water below, preventing it from freezing and allowing life to exist under the frozen surface.

Front 23

solution

Back 23

liquid that is completely homogeneous mixture of 2 or more substances

Front 24

solvent vs solute

Back 24

solvent = dissolving agent sugar or whatever= solute

Front 25

aqueous solution

Back 25

solution where water is solvent

Front 26

why water is an effective solvent

Back 26

- polarity of molecules
readily forms hydrogen bonds with charged and polar covalent molecules
- polar molecules are also soluble in water because they form hydrogen bonds with water
0 large molecules can disolve if they have ionic and polar regions

Front 27

hydration shell

Back 27

water molecules surrounding dissolved ions

Front 28

hydrophillic

Back 28

water loving
dominated by ionic or polar bonds
molecules that are too large dont dissolve (example cotton attracts water but cellulose is too big to be dissolved)

Front 29

hydrophobic

Back 29

water fearing
nonionic and have nonpolar covalent bonds
- no consistant regions with partial or full charges so water molecules cannot form hydrogen bonds
- oils
- cell membranes

Front 30

moles

Back 30

unit... 6.02x 10 23 molecules
equal to the molecular weight of a substance but scaled up from daltons to grams

Front 31

advantages to using moles

Back 31

a mole of one substance has the same number of molecules as a mole of any other substance
- allows scientists to combine substances in fixed ratios of molecules
-

Front 32

molarity

Back 32

concentration of a material in solution
- one molar solution has one mole of a substance dissolved in one liter of solvent

Front 33

h2- <=> H+ + OH

Back 33

water molecule dissociates into a hydrogen ion and a hydroxide ion

at equilibrium the concentration of water molecules greatly excedes H+ and oh-

both ions are very reactive and changes in concentrations drastically affect the chemistry of a cell

Front 34

ph scale

Back 34

how acidic or basic a solution is
1-14
ph= -log[h+] or [h+]= 10-pH

Front 35

acid

Back 35

a substance that that increases the hydrogen ion concentration in a solution

hydrochloric acid in water, hydrogen ions dissociate from chloride ions

hcl-> h++ Cl-
each pH unit represents a tenfold difference in h+ and oh- concentrations
small change in pH is large change in concentrations

Front 36

base

Back 36

reduces hydrogen ion concentration
some bases directly accept hydrogen ions sych as ammonia nh3

- other bases just dissociate oh- which combines with h+ to form water

Front 37

strong vs weak acids and bases

Back 37

strong- molecules disociate completely in water
weak-- binding and release of hydrogen ions are reversible

Front 38

product of h+ and OH- concentration

Back 38

always constant at 10-14 in any solution

Front 39

buffers

Back 39

resist changes to the ph of a solution when h+ or oh - is added to the solution to maintain cellular pH at a constant level
- usually consist of a weak acid and its corrosponding base
-- example: carbonic acid in human bloodwhich dissociates into bicarbonate ion and ydrogen ion

Front 40

acid precipitation

Back 40

occurs when raid snow or fog is more acidic than 5.6
caused primarily by sulfur oxides and nitrogen oxides in atmosphere
react with water to form strong acids that fall to the surface with rain or snow

Front 41

main source of oxides that cause acid rain

Back 41

burninf of fossil fuels like coal oil and gas
smokestacks spread the pollution so it effects far away areas

Front 42

effects of acids in lakes and streams are most pronounced when?

Back 42

spring during snowmelt. meltwater accumulates acid and brings it to lakes and streams all at once
can impact egga and early developmental stages of aquatic organisms

Front 43

acid precipitation impact on sols

Back 43

affects solubility of soil minerals
wash away key soil buffers and plant buffers and increase toxic compounds