Chapter 2 - Water

Question 1

What are the fluid phases of water?

Answer 1

Gas (steam/vapor)
Liquids (Water)

Question 2

What are the condensed phases of water?

Answer 2

Liquids (water)
Solids (ice)

Question 3

Name 5 reasons why water is essential for biochemistry.

Answer 3

1. Medium for most biochemistry reactions (transportation - taking meds)
2. Common reactant
3. Part of cellular components (protein, cell membrane)
4. Covers 70% of earth’s surface
5. Helps maintain body temperature (sweat, we dont freeze in cold)

Question 4

In which phase are molecules easy to observe??

Answer 4

gas phase - they’re far away

Question 5

Gasses are measured under what conditions??

Answer 5

Standard temperature and pressure (1atm, 0 degrees celsius)

Question 6

Water has a high ______

Answer 6

specific heat, boiling point

Question 7

What is the essential feature of the gas phase?

Answer 7

There is effectively no interaction with other molecules

Question 8

Properties of gasses are essentially the same, as long as they are under_____

Answer 8

STP

Question 9

A water molecule is ______overall

Answer 9

neutral

Question 10

A perfect tetrahedral conformation is _______degrees, but water is ______degrees due to ______

Answer 10

A perfect tetrahedral conformation is 109.5 DEGREES, but water is 104 DEGREES due to the lone pairs on oxygen

Question 11

How many valence electrons does oxygen have?

Answer 11

6

Question 12

In a covalent bond, sharing is usually ______

Answer 12

unequal

Question 13

The only time when electrons are shared completely equally in a covalent bond is when…?

Answer 13

covalent bond between identical atoms (N2 or O2)

Question 14

Unequal sharing of electrons leads to _______

Answer 14

partial charges

Question 15

The electronegativity scale runs from ____to____

Answer 15

0 to 4

Question 16

On the periodic table, which elements are the most electronegative??

Answer 16

The elements at the top right of the periodic table

Question 17

Is CO2 polar or nonpolar? why?

Answer 17

nonpolar because the vectors cancel each other out

Question 18

What are the 2 INCOMPRESSIBLE states of water? What does this mean?

Answer 18

solid and liquid. the external pressure causes the molecules to not be able to move closer together

Question 19

Are hydrogen bonds covalent bonds?

Answer 19

NO

Question 20

On their own, hydrogen bonds are _____

Answer 20

weak

Question 21

Together, hydrogen bonds form a very strong lattice structure. What does this explain about water?

Answer 21

Its peculiar properties

Question 22

As water freezes to ice, its density…..

Answer 22

DECREASES

Question 23

As ice melts to water, density…?

Answer 23

increases

Question 24

At what temperature does water reach its maximum density?

Answer 24

4 degrees celsius

Question 25

The uniqueness of water stems from which 2 things?

Answer 25

electronegativity difference (large) and the geometry of its hydrogen bond interactions

Question 26

The process of surrounding ions with water molecules is called...?

Answer 26

hydration

Question 27

What is specific heat?

Answer 27

The amount of energy needed to increase the temperature of 1 gram of a substance by 1 degree celsius

Question 28

Water acts as a _________

Answer 28

temperature buffer. heat loss or gain is smaller in water compared to other substances

Question 29

As temperature of water increases, the H bonds _____ but dont _____

Answer 29

bend but dont break

Question 30

Which phase of water does NOT have a high specific heat?

Answer 30

ICE. The H bonds cannot bend in this phase

Question 31

What is the definition of an acid?

Answer 31

Species that increase the hydrogen ion concentration when added to water

Question 32

What are bases?

Answer 32

Species that DECREASE the hydrogen ion concentration when added to water

Question 33

NaCl dissolves in water to form a ______ solution

Answer 33

neutral

Question 34

NH3 is a _____?

Answer 34

weak base

Question 35

ph=

Answer 35

-log[H+]

Question 36

What is the pH of the blood?

Answer 36

7.4

Question 37

pka=

Answer 37

-logka

Question 38

The flat region on a titration curve is known as the ____________ and is the numeric value of _______

Answer 38

buffering region, pka

Question 39

All weak acids and bases are _______

Answer 39

buffers

Question 40

What is the most significant physiological buffer?

Answer 40

blood bicarbonate buffer

Question 41

CO2 is technically a(n)____

Answer 41

acid

Question 42

What is 3 mol in avagadro's number??

Answer 42

18 * 10^23

Question 43

A chemical is more stable when it contains ______energy

Answer 43

less

Question 44

Low pka = ____aciditiy

Answer 44

HIGH

Question 45

low ka = ___Acidity

Answer 45

LOW

Question 46

At what temperature does water have the smallest VOLUME

Answer 46

4/5 degrees celsius

Question 47

Water can be considered a ____ of oxygen

Answer 47

hydride

Question 48

Why does decane have a slight affinity for water?

Answer 48

induced dipole attraction

Question 49

Does a substance NEED to provide OH- to be considered basic?

Answer 49

NO

Question 50

What is the pH of our stomach acid when we're hungry?

Answer 50

1-2

Question 51

If pH is 5 what is the [H+] ion concentration?

Answer 51

0.00001 mol/L