2.10-2.16

Question 1

Where do water’s life-supporting properties come from?

Answer 1

the structure and interaction of its molecules (polarity and resulting hydrogen bonds)

Question 2

How long do hydrogen bonds between molecules last?

Answer 2

trillionth of a second

Question 3

What is the property of water that comes from hydrogen bonding?

Answer 3

Cohesion/surface tension. It is much stronger in water than many other liquids.

Question 4

How does the cohesion of water supports tree life?

Answer 4

When water evaporates, it pulls on the water to come up. Without cohesion, those particles would not come up together.

Question 5

How does adhesion play a role in how water supports tree life?

Answer 5

Water adheres itself to cell walls when traveling up through plants veins, which counteracts gravity.

Question 6

Define surface tension. What is water’s surface tension like?

Answer 6

measure of how difficult it is to stretch or break the surface of a liquid. Hydrogen bonds=unusually high surface tension.

Question 7

What is the classic example of water’s surface tension/cohesion?

Answer 7

the meniscus of an overfilled glass of water.

Question 8

What creates beads of sweat?

Answer 8

The cohesion and surface tension of water.

Question 9

Define thermal energy

Answer 9

kinetic (random movement) of atoms and molecules.

Question 10

Define heat

Answer 10

thermal energy in transfer from a warmer to a cooler body.

Question 11

Define temperature

Answer 11

the intensity of the heat or the average kinetic energy of the particles

Question 12

Define specific heat

Answer 12

the amount of heat needed to raise the temperature of 1 gram of a substance 1 degree Celsius (°C).

Question 13

Why does it take so long for water to heat up?

Answer 13

Because of hydrogen bonding; very high specific heat.

Question 14

To increase the thermal energy of water, what process must it undergo?

Answer 14

To make water particles move faster, hydrogen bonds must be broken. When they are broken, they release heat and allow for thermal energy to increase. Water absorbs much heat while only heating up slightly.

Question 15

What happens when water cools?

Answer 15

hydrogen bonds are reformed; water releases immense amounts of heat

Question 16

What role do oceans, lakes and rivers play in regulation of the earth’s temperature?

Answer 16

They absorb and store much of the heat from the sun during hotter areas. They give off heat gradually.

Question 17

Why are coastal areas’ temperatures more mild?

Answer 17

because more heat is stored and let off slowly by body of water.

Question 18

What role do oceans, lakes and rivers play in temperature and marine life? in you?

Answer 18

Because of its high specific heat, marine life is able to flourish. Humans are made 66% of water, and it is key for homeostasis.

Question 19

Define evaporative cooling.

Answer 19

occurs because the molecules with the greatest energy leave. When a substance evaporates, the surface of the liquid that reminds behind cools down.

Question 20

Why is evaporative cooling important.

Answer 20

helps terrestrial organisms from overheating (sweating, ex.), leaves becoming too dry, cools tropical sea by evaporation of surface water.

Question 21

Explain the popular adage, “it’s not the heat, it’s the humidity”

Answer 21

High humidity hampers cooling by slowing the evaporation of sweat.

Question 22

Why is ice less dense than liquid water?

Answer 22

Hydrogen bonds; they crystalize/lattice themselves to be the same (further) distance away from other molecules.

Question 23

If ice sunk, what would happen to life?

Answer 23

ponds, lakes and oceans would freeze solid. But ice actually acts as an insulator for the warmer water below in cool temperatures.

Question 24

Explain how freezing water can crack boulders.

Answer 24

Water in the crevices of a boulder expands as it freezes because the water molecules become spaced farther apart, in forming crystal ice.

Question 25

Define solution

Answer 25

a liquid consisting of a uniform mixture of two or more substances.

Question 26

Define solvent

Answer 26

dissolving agent, ex, water.

Question 27

Define solute

Answer 27

the dissolved; salt.

Question 28

Why is water so versatile as a solvent?

Answer 28

The polarity of its atoms. Take salt, which consists of the ionically bonded Na+ and Cl-. The charges of the hydrogen and oxygen in the covalent bond pull apart this ionic bond in favor of being attracted to the different atoms within the water molecules. This can also happen with covalent bonds, such as sugar. This process happens in a lot of seawater.

Question 29

Why is blood and most other biological fluids classified as aqueous solutions?

Answer 29

Because the solvent is water.

Question 30

What does a water molecule break into to determine its pH level?

Answer 30

H+ and OH-. (in very small amounts)

Question 31

H+ is…

Answer 31

….a hydrogen ion

Question 32

OH- is…

Answer 32

…a hydroxide ion

Question 33

What is true about the pH ions?

Answer 33

They are very reactive.

Question 34

What does an acid have a higher concentration of?

Answer 34

H+. Ex. hydrochloric acid (HCl).

Question 35

What does a base have a higher concentration of?

Answer 35

OH- ions. It reduces the the hydrogen ion concentration. ex. NaOH (sodium hydroxide) donates the OH to H+ to make more water and reduce H+ ions.

Question 36

Define pH scale.

Answer 36

A range from 0-14, where 14 is most basic and 0 is most acidic. Each unit represents a 10 fold change in the concentration of H+ in a solution.

Question 37

pH 7 is neutral, equal concentrations. What aqueous solutions have that or are near to that?

Answer 37

pure water, pH inside most cells.

Question 38

What is a buffer, for pH levels?

Answer 38

substances that minimize change in pH. Accepting H+ and donating H+. An example is blood plasma, which must have a pH between 7.0-7.8

Question 39

Compared to a basic solution at pH 9, the same volume of an acidic solution at pH 4 has________times more H+

Answer 39

100,000

Question 40

What is the naturally occurring remedy for excess CO2

Answer 40

The ocean consumers 25% of it.

Question 41

Define ocean acidification

Answer 41

CO2 dissolving in seawater lowers the pH of the ocean. by end of 21st century, pH levels could go from 8.1-7.8 (more change than in last 420,000 years)

Question 42

How does ocean acidification affect processes within corals reefs?

Answer 42

Excess hydrogen ions combine with carbonate ions (CO3 2-) to create bicarbonate ions (HCO3 -). Calcifers, or marine organisms that use carbonate ions to create their shells, are facing drastic changes in the amount of this ion available to them to make their shells. They then reduce their diversity, recruitment of juvenile coral animals. This is bad, as coral reefs contribute so much to oxygen levels, etc.

Question 43

Why might there be life on Mars?

Answer 43

Mars has ice poles, that are, or have melted in the past. There also might be water underground.

Question 44

Why is the presence of water important in the search for extraterrestrial life?

Answer 44

Water plays important roles in life as we know it, from moderating temperatures on the planet to functioning as the solvent of life.