Properties of water Flashcards
1
Q
substance that makes all life possible
A
water
2
Q
All familiar organisms are made mostly of
A
water
3
Q
water is the Only substance to exist in
A
all three states
4
Q
Water’s unique behavior is related to its
A
structure and interaction of it’s molecules
5
Q
water molecule shape
A
a wide V with two hydrogen atoms joined to the oxygen atom by single covalent bonds
6
Q
properties of water come from the
A
attractions between oppositely charged atoms of different molecules
7
Q
hydrogen bond
A
The hydrogen of one water is attracted to the oxygen of another
8
Q
In the liquid form, hydrogen bonds are
A
fragile
9
Q
why are hydrogen bonds fragile
A
They form, break and reform very frequently
10
Q
which atom is is more electronegative in water
A
oxygen
11
Q
what does it mean that oxygen has a higher electronegativity
A
electrons in the covalent bond spend time closer to it
12
Q
The oxygen region has a partial
A
negative charge
13
Q
the hydrogen region has a
A
partially positive charge
14
Q
The overall charge of water is unevenly distributed because
A
unequal sharing of electrons
15
Q
Four emergent properties of water
A
- Cohesive behavior
- Ability to moderate temps
- Expansion upon freezing
Versatility as a solvent
16
Q
Cohesion of water molecules
A
the molecules stay close together because of the hydrogen bonding
17
Q
cohesion contributes to what in plants
A
transport of water and dissolved nutrients against gravity
18
Q
hydrogen bonds cause water molecules to do what in plants
A
water molecules in veins to tug on those farther down
19
Q
Adhesion
A
the clinging of one substance to another
20
Q
adhesion in plants
A
Adhesion of water by hydrogen bonds to molecules of the cell walls counters the downward pull of gravity
21
Q
surface tension is related to
A
cohesion
22
Q
surface tension
A
Measure of how difficult it is to stretch or break the surface of a liquid
23
Q
water has a ______ surface tension
A
high
24
Q
why does hydrogen have a high surface tension
A
hydrogen bonding between the molecules of the air and water below
25
how does water moderate air temps
by absorbing heat from warmer air and releasing stored heat to colder air
26
why is water an effective heat bank
can absorb or release a large amount of heat with only slight changes in own temp
27
why does a desert have huge temp changes
there is no water to moderate the temp
28
places closer to the ocean will have ____ temp fluctuations
less
29
When two objects of different temps are brought together, the
Thermal energy passes from the warmer object to the cooler one
30
when does the thermal energy stop passing from the warmer object to the cooler one
when they are the same temp
31
Molecules in cooler objects
Speed up at the expanse of the thermal energy of the warmer object
32
Kinetic energy:
The energy of motion
33
. Anything that moves has this energy
kinetic energy
34
The faster the movement the greater the
kinetic energy
35
Thermal energy
Kinetic energy associated with the random movement of atoms or molecules
36
thermal energy reflects
total kinetic energy
37
Temperature
The average kinetic energy of molecules in a body of matter
38
does volume matter for temp
nope
39
Heat
Thermal energy transferred from one body of matter to another
40
heat is measured in
Joules
41
1 cal
4.184 J
42
heat is also measured in
calories
43
calories
. Heat needed to raise the temp of 1 g of water by 1 degree Celsius
44
Water's high specific heat has the ability to
stabilize temps
45
why can water stabilize temps
because of it's relatively high specific heat capacity
46
Specific heat
1. The amount of heat that must be absorbed or lost for 1 g of that substance to change temps by 1 degree Celsiu
47
Water has a specific heat of
4.18
48
Water changes it's temp less than other liquids when it
absorbs or loses heat
49
water loses a _____ amount of water with each degree of change
large
50
The high specific heat of water can be traced to the
hydrogen bonds
51
To beak hydrogen bonds,
heat must be absorbed
52
when hydrogen bonds form they
release heat
53
before a water molecule can move faster
the heat goes towards disrupting the hydrogen bonds
54
When water temp drops slightly
releases large amount of energy in HEAT
55
what is the relevance of water's specific heat capacity
Large body of water
a. Can absorb and store huge amounts of heat from the sun
b. Only warms up a few degrees
56
high specific heat capacity of water creates
a favorable environment for marine life
57
Evaporative cooling
Liquid evaporates and the surface left behind cools down (temp decreases)
58
the hottest molecules are the most likely
to become gas
59
evaporating cooling contributes
to the stability of temps in lakes and ponds
a mechanisms that prevents the organism from overheating
60
Molecules stay close together because
they are attracted to one another
61
Molecules must moving fast enough
overcome these attractions
62
VAPORIZATION or EVAPORATION
Depart the liquid phase and enter the air as gas
63
even at the low temps, the speediest molecules can
escape into the air
64
Heat of vaporization
1. Quantity of heat a liquid must absorb for 1 g to be converted from liquid to gas
65
water has a ____ heat of vaporization compared to other liquids
high
66
heat of vaporization is an emergent property from
strength of hydrogen bonds
67
what must be broken before the molecule can exit liquid stage into the water vapor
the hydrogen bonds
68
Water is one of the few substances that is ____ dense as a solid than a liquid
less
69
what does water do when it solidifies
expands
70
what causes this expansion as water turns solid
the hydrogen bonds
71
when water is at a temp above 4 degree Celsius
Water is like any other liquid
72
Temps from 4 degree Celsius to 0 degree Celsius
Water begins to freeze as more and more of it's molecules are moving too slowly to break hydrogen bonds
73
At 0 degree Celsius
Molecules become locked together in a crystalline lattice
74
Hydrogen bonds keep the molecules _____ apart than at 4 degree Celsius
farther
75
When ice absorbs enough heat for the temp to rise above 0 degree Celsius
Hydrogen bonds between molecules are shattered
76
At 4 degree Celsius water has reached
its greatest density
77
floating ice on water allows the liquid below to be
insulated and stops it from freezing
78
how is Global warming affecting ice
a. Ice has formed later in the year and melts earlier
b. It covers a smaller area
79
why is Water a very versatile solvent
polarity of water molecules
80
A compound does not need to be _____ to dissolve in water
ionic
81
how do non-ionic molecules dissolve in water
water molecules surround each of the solute molecules and form hydrogen bonds with them
82
Large molecules like proteins can dissolve in water if
they have polar regions on their surface
83
Solution
1. A liquid that is a completely homogeneous mixture of two or more substances
84
Solvent
Dissolving agent of a solution
85
Solute
1. Substance that is dissolved
86
Aqueous solution
The solute is dissolved in water
87
Hydration shell
The sphere of water molecules that surround a dissolved ion and prevent those ions from rejoining together
88
Working inward, water will eventually do what to the ions
dissolve them all
89
Hydrophilic
1. Any substance that has an affinity (liking) for water
90
can something be hydrophilic without dissolving in water
yes, think of a cotton towel
91
Hydrophobic
1. Substances that are non-ionic and non-polar (can't form hydrogen bonds)
92
Molecular mass
Sum of the mass of all atoms in a molecule
93
Mole (mol)
6.02 x 10^23
94
6.02 x 10^23 daltons in
1 gram
95
Moles of one substance equals the same number
MOLECULES as a mole of another substance
96
Molarity
Number of moles of solute per liter of solution
97
a hydrogen atom can shift between
two water molecules during a hydrogen bond
98
Hydrogen ion (H+)
A single proton with a charge of 1+
99
H+ does NOT exist on
its own in an aqueous solution
100
h+ Always associated with a water molecule in the form
H3O
101
Hydroxide ion (OH-)
The water molecule that lost a proton
102
Dissociation of water importance
H+ and OH- are very reactive and concentration changes can affect a cell's proteins
103
in pure water, H+ and OH- are
equal in concentration
104
Acids
donate H+ ions when dissolved in water
105
Substance that increases the hydrogen ion concentration of a solution
acid
106
An acidic solution has more
H+ to OH-
107
Base
1. Reduces the hydrogen ion concentration of a solution
108
Some bases reduce H+ concentrations directly by accepting Hydrogen ions
Ammonia
109
Other bases reduce H+ concentration indirectly by dissociating to form hydroxide ions
Sodium hydroxide
110
Basic solutions
Have a higher concentration of OH- than H+
111
Neutral solutions
Solutions that have equal H+ and OH-
112
Strong Base and acids
Compounds that dissolve completely when mixed with water
113
what is not a reversable reaction when used
Strong Base and acids
114
The reaction is reversible when using
Weak acid or base
115
The PH scale
Compresses the range of H+ and OH- concentrations by logarithms
116
each jump in the PH scale is a jump in
ten
117
EXAMPLE
Ph of 3 to PH of 6
It is a thousand times more acidic (10 x 10 x 10)
118
PH formula
PH = -log [H+]
119
Ph _____ as H+ concentrations increase
declines
120
Neutral solutions formula
-log 10-7 = -(-7) = 7
121
PH above 7
Basic solutions
122
PH of less than 7
Acidic solution
123
An acid not only adds hydrogen ions to a solution but it also
removes hydroxide ions
124
A base increases OH- concentrations but also
reduced H+ concentrations by the formation of water
125
Buffers
substance that minimizes changes in concentrations of H+ and OH- in a solution
126
buffers must be
weak acids and its corresponding base
127
how do buffers work
1. Buffers accept hydrogen ions from the solution when they are in excess
2. Donate hydrogen ions to the solution when there aren't enough
128
