Chapter 3: Water and Life

Question 1

Cohesion

Answer 1

linking together of like molecules, often hydrogen bonds

Question 2

Adhesion

Answer 2

the clinging of one substance to another,

such as water to plant cell walls by hydrogen bonds

Question 3

Surface Tension

Answer 3

measure of how difficult it is to stretch or break the surface of a liquid

water has a high surface tension because of hydrogen bonds

Question 4

Kinetic Energy

Answer 4

the energy associated with the relative motion of objects

Question 5

Thermal Energy

Answer 5

kinetic energy due to the random motion of atoms.

energy in its most random form

Question 6

Temperature

Answer 6

a measure in degrees of the average kinetic energy of the atoms and molecules in a body of matter

Question 7

Heat

Answer 7

thermal energy in transfer from one body to another

Question 8

Calorie

Answer 8

the amount of heat required to raise the temp of 1g of water by 1 degree C

Question 9

Solution

Answer 9

a liquid, homogeneous mixture of 2 or more substances

Question 10

Evaporative Cooling

Answer 10

surface of an object becomes cooler during evaporation

example: sweating

Question 11

Solute

Answer 11

Substance dissolved in a solution

Question 12

Ocean Acidification

Answer 12

process by which the pH of the ocean is lowered when excess CO2 dissolves in seawater
(CO2 dissolves and forms Carbonic Acid, aka making the water more acidic)

Question 13

Aqueous Solution

Answer 13

solution with water as the solvent

Question 14

Hydrophilic

Answer 14

affinity for water

Question 15

Hydrophobic

Answer 15

no affinity for water (like repels water)

Question 16

Hydrogen Ion

Answer 16

a single proton w/ a charge of 1+.

h20-> -OH&H+

Question 17

Hydroxide Ion

Answer 17

water molecule that lost a proton; OH-

Question 18

Hydronium Ion

Answer 18

a water molecule that has an extra proton bound to it; H30, commonly referred to as H+

Question 19

Buffers

Answer 19

solution that contains a weak acid and its corresponding base.
-minimizes changes in pH when acids or bases are added to the solution

Question 20

Discuss the 4 unique characteristics/qualities of water. List each one, then define.

Answer 20

• Cohesion: water sticks to itself because of hydrogen bonds constantly clinging to each other. This creates surface tension.
• Ability to moderate temp: High specific heat makes water suitable for life, prevents temp fluctuations. Evaporative cooling, cools surface on evaporation.
• Expansion on Freezing: water is densest at 4 degrees Celsius. anything above or below is less dense. While water above 4 degrees floats freely, hydrogen molecules between 0-4 degrees stay far apart (they’re slowed down). So ice expands, and floats.
• Versatility as a solvent: bc of its polarity, water is a universal solvent. non-ionic polar molecules and large polar molecules like protein dissolve in polar regions

Question 21

How do the qualities of cohesion and adhesion of water allow plants to uptake and distribute water throughout their bodies?

Answer 21

• Hydrogen bonds in H2O cause Cohesion
• Water evaporates from leaves
• Evaporating water (bc of hydrogen bonds) pulls water in stem up to leaves, and in roots up to stem
• The adhesion (by hydrogen bonds again) clinging to the cell walls also helps the water counter the downward pull of gravity