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BIOL 1020 > Water- lecture #3 > Flashcards

Water- lecture #3 Flashcards

1
Q

when do polar covalent bonds form?

A

when two atoms involved in a covalent bond do not have equal electronegativity

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2
Q

Carbon is more electron loving than hydrogen, what does that mean for sharing of electrons?

A

electrons are equally shared in between the two atoms

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3
Q

oxygen is more electron loving than hydrogen, what does that mean for the sharing of electrons?

A

electrons are not equally shared in between the two atoms and are held more closely to the oxygen nucleus

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4
Q

when the electrons are not equally shared in between the two atoms what happens to the charge?

A

a resulting partial charge on the hydrogen (+) atom and a partial negative (-) charge on the electron loving atom

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5
Q

what are polar molecules?

A

molecules that contain unequal sharing of electrons

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6
Q

in a bond with Na+ and water (H2O) what gets created?

A

solvation cage
this cage gets created because the (-) oxygen stays closer to the (+) nucleus, therefore all the hydrogens end up outside the solvation cage

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7
Q

what are the top 3 elements most greedy for electrons?

A

florine
oxygen
nitrogen

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8
Q

what kind of bonds are used in water molecules?

A

hydrogen bonds using the oppositely charged atoms

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9
Q

the partial positive charge on the hydrogen atom is attracted to what?

A

the partial negative charge on atoms within OTHER molecules

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10
Q

are hydrogen bonds stronger than covalent and ionic bonds?

A

no, they are weaker

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11
Q

hydrogen bonds create molecular networks, these networks occur between what types of molecules?

A

identical and different molecules

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12
Q

what are the two important properties of water?

A

cohesion of water molecules
temperature moderation

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13
Q

does hydrogen bonding keep water molecules close or far from one another? what does this create?

A

close
creates a complex structure

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14
Q

what is cohesion?

A

hydrogen bonding keeping water molecules close to one another
(water likes to stick to itself)

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15
Q

what does cohesion allow for?

A

water to move against gravity from root to shoot in plants
(water likes to stick to other things)

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16
Q

water is also subject to adhesion, what does that mean?

A

The molecules hydrogen bond to the walls of the vessels in the plant preventing them from falling back down

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17
Q

what is temperature moderation?

A

Water absorbs heat from air that is warmer and releases heat to air that is cooler

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18
Q

what type of energy is associated with motion?

A

kinetic energy

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19
Q

if the atoms and molecules move fast, what does that do to kinetic energy?

A

increases

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20
Q

what is heat a measure of?

A

the total kinetic energy of a body

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21
Q

how does heat transfer?

A

from hotter object to a cooler object

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22
Q

what happens to the molecules in the cooler object when heat is transferred from hot to cold?

A

start to speed up because of the gain of kinetic energy

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23
Q

is heat volume independent or volume dependent?

A

volume dependent

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24
Q

is temperature volume independent or volume dependent?

A

volume independent

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25
Q

temperature is the average what of molecules?

A

kinetic energy

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26
Q

what is a calorie?

A

the amount of heat needed to raise the temperature of 1 gram of water by 1oC

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27
Q

1 cal= how many joules?

A

4.184 Joules

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28
Q

what is specific heat?

A

the amount of heat that must be absorbed/lost in order to change the temperature of 1 gram of a substance by 1 degree C

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29
Q

does water have a high or low specific heat?

A

very high specific heat compared to other substances

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30
Q

why does water have such a high specific heat?

A

hydrogen bonding
heat needs to be used in order to break those hydrogen bonds, after the hydrogen bonds are broken the heat can then be used to increase the temperature of the water

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31
Q

what happens when water is cooled?

A

heat is released as hydrogen bonds are reformed between water molecules
results in a decreased speed of the molecules

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32
Q

what does evaporation of a substance do to temperature?

A

moderates temperature

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33
Q

what is something that is incredibly sensitive to temperature?

A

living systems

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34
Q

what occurs in evaporation?

A

molecules with the greatest energy (the hottest) leave the substance
remaining liquid is cooler as a result of this loss

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35
Q

what are examples of evaporation?

A

sweating, boiling water

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36
Q

why is water an excellent solvent?

A

It can dissolve many ionic compounds such as NaCl
The ions (Na+, Cl-) remain dissolved in the water and form a solution

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37
Q

why does the solution form between Na+ and Cl-

A

This solution forms because the partial positive regions within the water molecules surround the negative ions (Cl-) and the partial negative regions within the water molecule surround the positive ions (Na+)
This holds the ions in solution

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38
Q

what are the 3 primary states water exists in?

A

solid, liquid, gas (water vapor)

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39
Q

what is the most dense between solid, liquid and gas?

A

solid

40
Q

what is density?

A

the number of particles (molecules) per unit area

41
Q

what is the one exception to density?

A

water

42
Q

what has a smaller density, ice or liquid water

A

ice, this explains why ice cubes float in water (due to hydrogen bonds)

43
Q

what happens when water freezes?

A

each water molecule forms four hydrogen bonds with adjacent water molecules resulting in the creation of a crystal lattice

44
Q

are the hydrogen bonds developed with freezing temperature weak or stable?

A

extremely stable

45
Q

in liquid water are hydrogen bonds stable or less stable?

A

less stable and continually break and reform

46
Q

what is a solution?

A

a liquid consisting of a uniform (homogenous) mixture of two or more substances

47
Q

what is a solvent?

A

dissolving agent
example: water

48
Q

what is a solute?

A

dissolved substance
example: sugar, salt

49
Q

when water is the solvent the solution is referred to as what type of solution?

A

aqueous solution

50
Q

why is water such a great solvent?

A

because of the polarity of the molecules

51
Q

what happens to NaCl in water?

A

it dissociates forming Na+ and Cl- ions

52
Q

what does the partial positive (+) charge on the hydrogen and the partial negative (-) charge from oxygen (from water) interact with in respect to NaCl

A

partial positive: Cl-
partial negative: H+

53
Q

what is a non-ionic material?

A

polar molecules that have unequal charge distribution

54
Q

what are examples of non-ionic materials?

A

proteins and sugars

55
Q

can non-ionic materials dissolve in water?

A

yes

56
Q

can non-ionic materials participate in hydrogen bonding with water?

A

yes

57
Q

are hydrophilic substances water loving or water hating?

A

water loving (have an affinity for water)

58
Q

do hydrophilic substances dissolve in water?

A

yes, if not too large

59
Q

if hydrophilic substances are too large what do they form?

A

a colloid

60
Q

what is a colloid?

A

stable suspension of fine particles in a liquid

61
Q

are hydrophilic substances polar or non-polar?

A

polar

62
Q

are hydrophobic substances water loving or water hating?

A

water hating (zero affinity for water)

63
Q

are hydrophobic substances polar or non-polar?

A

non-polar (non-ionic)

64
Q

what is an example of a hydrophobic substance?

A

oil
oil and water will not mix

65
Q

what is the equation for glucose?

A

C6 H12 O6

66
Q

how many daltons does carbon weigh?

A

12

67
Q

how many daltons does hydrogen weigh?

A

1 dalton

68
Q

how many daltons does oxygen weigh?

A

16 daltons

69
Q

what is the weight of glucose in daltons?

A

180 daltons
6x12= 72 daltons (carbon)
12x1= 12 daltons (hydrogen)
6x16=96 daltons (oxygen)

70
Q

what is molar mass?

A

the number of grams one mole of a substance weighs
glucose is 180g/mole

71
Q

what is molarity?

A

the number of moles of solute/ liter of solution

72
Q

what can be said about this
H2O <—————> H+ + OH-

A

the hydrogen ion has left its electron behind
(free in solution as an H+ ion)
OH- that results is the hydroxide ion

72
Q

what can be said about this
H2O <—————> H+ + OH-

A

the hydrogen ion has left its electron behind
(free in solution as an H+ ion
OH- that results is the hydroxide ion

73
Q

what can be said about this
2 H2O <——————> H3O+ + OH-

A

the lost proton attaches to the second water molecule

74
Q

in pure water H+ = what?

A

H+ = OH-

75
Q

an addition of acid or base will do what to the balance of H+ = OH-?

A

disrupt this balance

76
Q

do acids dissociate when placed in water?

A

yes, they release H+ ions

77
Q

the more HCl that is added to water will cause what?

A

more H+ to be present following dissociation

78
Q

if theres a high amount of H+ in the solution what happens to the pH of the solution?

A

lower pH (more acidic)

79
Q

do bases dissociate in water?

A

yes, they release OH- ions

80
Q

the OH- that is generation from the dissociation of NaOH binds to what?

A

H+

81
Q

if theres a high amount of OH- in the solution, what will that do to the pH?

A

higher pH (more basic)

82
Q

what does a double sided arrow indicate
(<———->)

A

weak acid will have incomplete dissociation

83
Q

what is the pH scale measured on a scale of?

A

0-14

84
Q

if the amount of H+ in solution is equal to the amount of OH- in solution, what does that indicate about the pH?

A

pH is 7
solution is neutral

85
Q

on the pH scale, what is considered to be acidic?

A

pH 1 to 6 is acidic

86
Q

on the pH scale what is considered to be basic?

A

pH 8-14

87
Q

what will the addition of H+ do to OH- in a solution?

A

cause the OH- to decrease

88
Q

what will the addition of OH- do to H+ in a solution?

A

cause the H+ to decrease

89
Q

what does a difference of 1 pH unit represent in respect to H+ concentration?

A

1000x difference in H+ concentration

90
Q

what is a buffer?

A

substances that allow a solution to offset large and potentially dangerous changes in pH from occuring

91
Q

what is threatened by very small changes in pH?

A

living systems

92
Q

what is an example of a buffer found in the blood?

A

carbonic acid (H2CO3)

93
Q

H2 CO3 <————> H+ + HCO3-
if blood pH drops what will bind to the excess H?

A

HCO3

94
Q

H2 CO3 <————> H+ + HCO3-
if blood pH increases what will bind to the excess OH-

A

H+

95
Q

H2 CO3 <————> H+ + HCO3-
what is the result of these buffers?

A

the blood pH will not change dramatically

BIOL 1020 (16 decks)

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