2 Water as a vehicle for life

Question 0

hydrogen bonding

Answer 0

attraction between H atom in a polar covalent bond and another electronegative atom

Question 1

Oxygen

Answer 1

stronger attraction for electrons (more electronegative-pulls electrons toward it)

Question 2

solution

Answer 2

liquid that is a homogenous (of the same) mixture of substances

Question 3

solute

Answer 3

dissolving agent of a solvent and a substance which is dissolved

Question 4

aqueous solution

Answer 4

water is the solvent (each ion is surrounded by a hydration shell)

Question 5

hydration shell

Answer 5

the sphere of water molecules around each dissolved ion

Question 6

Cations

Answer 6

• positive ions

- oxygen closet

Question 7

anions

Answer 7

• negative ions

- hydrogen closet

Question 8

Water as a solvent can dissolve many types of solutes:

Answer 8

• Ionic molecules
• compounds made of non-ionic polar molecules
• large polar molecules (ex. proteins) if they have ionic and polar regions

Question 9

hydrophilic substance

Answer 9

has an affinity for water (relatively polar bonds)

Question 10

hydrophobic substance

Answer 10

does not have an affinity for water (relatively non-polar bonds)

Question 11

H-bonding in ice is more ordered than in liquid water because…

Answer 11

• ice is less dense than water

- ice is solid and has a larger volume

Question 12

freezing point depression

Answer 12

presence of solutes decreases the freezing point of a solvent (seawater)

Question 13

Hydrogen bonds are constantly…

Answer 13

breaking and reforming

Question 14

What can high concentrations of solutes in some organisms do in cold climates?

Answer 14

can prevent body fluids from freezing

Question 15

Glycerol concentration in smelt blood (plasma)….

Answer 15

increases as temperature decreases

Question 16

liquid water

Answer 16

hydrogen bonds break and reform

Question 17

ice

Answer 17

hydrogen bonds are stable

Question 18

are cohesion and adhesion important in water transport in plants?

Answer 18

Yes

Question 19

Cohesion

Answer 19

sticking together (the hydrogen bonds hold the substance together)

Question 20

Adhesion

Answer 20

the clinging of one surface to another

adhesion of water by hydrogen bonds to the molecules of cell walls helps counter the downward pull of gravity

Question 21

as a result of hydrogen bonding what do water molecules do?

Answer 21

they stay close to each other

Question 22

surface tension

Answer 22

how hard it is to break the surface of a liquid

Question 23

Surface tension is high in water due to..

Answer 23

its cohesive behaviour. At the interface b/t water and air is an ordered arrangement of water molecules, hydrogen-bonded to on another and to the water below. this gives water an unusually high surface tension, making it behave as though coated with and invisible film. (water above the rim of a glass)

Question 24

does water has a high specific heat?

Answer 24

Yes

Question 25

What is the amount of heat to change temperature?

Answer 25

1 gram, raised by 1 degree celsius

Question 26

Calorie

Answer 26

the amount of heat it takes to raise the temperature of 1 g of water by 1 degree celsius

Question 27

specific heat of a substance is defined as..

Answer 27

the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree celsius (cal/g/degrees c)

Question 28

To change the temperature of something what do we apply?

Answer 28

heat

Question 29

temperature

Answer 29

the intensity of heat

Question 30

thermal energy

Answer 30

amount of kinetic energy due to molecular motion

Question 31

what happens because of the high specific heat of water relative to other materials...

Answer 31

water will change its temperature less than other liquids when it absorbs of loses a given amount of heat (pot heating before the water inside)

Question 32

Heat of vaporization

Answer 32

quantity of heat of liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state (large quantity of heat must be absorbed)

Question 33

What happens as liquid evaporates?

Answer 33

remaining surface cools

Question 34

Evaporative cooling helps stabilize temperature in organisms and bodies of water...

Answer 34

ex. a dogs tongue | Ocean absorbs heat from warmer air and releases stored heat to cooler air (only slight change in water temp.)

Question 35

water has a high...

Answer 35

specific heat and heat vaporization relative to most other liquids

Question 36

how much heat is need to evaporate 1g of water at 25 degrees Celsius?

Answer 36

2427 Joules (double is need for alcohol or ammonia)

Question 37

What bond must be broken before the molecules can make their exodus from the liquid?

Answer 37

hydrogen bonds

Question 38

H2O molecules dissociate the same rate at which...

Answer 38

they are being reformed

Question 39

When is there fewer fluctuation?

Answer 39

when there is a body of water near by

Question 40

acid

Answer 40

donates a proton to a solution, increases H+ concentration of a solution (gives)

Question 41

Base

Answer 41

accepts a proton from the solution, decreases H+ concentration of a solution (receives/accepts)

Question 42

Neutral solution

Answer 42

equal number of protons and hydroxide ions

Question 43

acidic solution

Answer 43

has more H+ than OH-

Question 44

Hydrogen leaves its electron behind...

Answer 44

therefore transferred as a proton (H+ ion) | molecules that lost H-1 becomes OH-

Question 45

basic solution

Answer 45

has more OH- than H+

Question 46

[H+][OH-]=10^-14

Answer 46

in any aqueous solution at 25 degrees C, the product of the H+ and OH- concentrations is constant at 10^-14

Question 47

p=-log[H+] (log base 10)

Answer 47

pH of a solution is defined as the negative logarithm (base 10) of the hydrogen ion concentration

Question 48

What would a neutral solution be using the pH scale?

Answer 48

7

Question 49

pH declines as...

Answer 49

H+ concentration increases

Question 50

most biological fluids are... (pH)

Answer 50

within the range of pH6-8 (human stomach is the exception with about a pH2)

Question 51

Changes in pH can drastically affect....

Answer 51

the chemistry of a cell

Question 52

Buffers

Answer 52

minimize changes in concentration of H+ and OH- in a solution (acid-base pair that reversibly combines with H+ (it does so by accepting hydrogen ions from the solution when they are in excess and donating hydrogen ions to the solution when they have been depleted. Most buffer solutions contain a weak acid and its corresponding base, which combine reversibly with hydrogen ions.)

Question 53

buffering in biological systems: EX

Answer 53

CO2->H2O H2CO3 HCO3- acts as buffers in your blood

Question 54

pH rises

Answer 54

less H+ in solution

Question 55

pH falls

Answer 55

more H+ in solutions

Question 56

When air pollutants mix with water in atmosphere what happens?

Answer 56

decreases pH | can fall at some distance

Question 57

Ocean water quality is at risk because..

Answer 57

when CO2 dissolves in seawater it reacts with water to form carbonic acid, which lowers ocean pH, a process known as ocean acidification, coral reefs are avery sensitive therefore this causes a decrease in the ability of corals to form calcified reefs)