Water and Life: Chp 3

Question 1

structure of water

Answer 1

the key to its special properties. water is made up of one atom of oxygen and two atoms of hydrogen, bonded to form a molecule

Question 2

what does a polar what molecule mean

Answer 2

the oxygen region of the molecule has a partial negative charge, and each hydrogen has a partial positive charge

Question 3

hydrogen bonds

Answer 3

form between water molecules. the slightly negative oxygen atom from one water molecule is attracted to the slight positive hydrogen end of another water molecule…each water molecule can form a max of 4 hydrogen bonds

Question 4

cohesion

Answer 4

the linking of like molecules…“water moleule joined to a water molecule”. this allows insects to walk on water

Question 5

adhesion

Answer 5

clinging of one substance to another…“water molecule attached to another molecule”. water droplets on a glass window

Question 6

transpiration

Answer 6

movement of water molecules up the very thin xylem tubes and their evaporation from the stomata in plants.

Question 7

specific heat

Answer 7

the amount of heat required to raise or lower the temperatire of a substance by 1 degree C. Relative to most other materials, the temperature of water changes less when a given amount of heat is lost or absorbed. this causes the oceans temperature to be relatively stable.

Question 8

water vs ice

Answer 8

water is less dense as a solid than it is in liquid state, whereas the opposite is true of most other substances, this causes ice to float.

Question 9

solvent

Answer 9

substance that something is dissolved in…water is an important solvent

Question 10

solute

Answer 10

substance being dissolved

Question 11

solution

Answer 11

the solvent and solute together

Question 12

hydrophilic

Answer 12

hydrophilic substances are water-soluble. these include ionic compounds, polar molecules, and some proteins.

Question 13

hydrophobic

Answer 13

hydrophobic substances are not dissolvable in water adn are nonpolar. ex: oils

Question 14

pH

Answer 14

scale that measures the relative acidity and alkalinity of aqueous solutions. Runs between 0 and 14.

Question 15

acids

Answer 15

have an excess of H+ ions and a pH below 7.0

Question 16

bases

Answer 16

have an excess of OH- ions, and a pH above 7.0

Question 17

neutral

Answer 17

pH of 7…EX: water

Question 18

buffers

Answer 18

substances that minimize changes in pH. They except H+ from solutions when they are in excess and donate h+ when they are depleted.

Question 19

carbonic acid (H2CO3)

Answer 19

an important buffer in living systems. It moderates pH changes in blood plasma and the ocean