States Of Matter And Changes Of State Flashcards
(110 cards)
1
Q
Gases are well described by ___
A
Gas laws—no such laws exist for solids or liquids
2
Q
Kinetic-molecular theory of matter attempts to describe…
A
All states of matter and conversion between states
3
Q
Solids have a definite ___ and ___
A
Volume and shape
4
Q
Molecules of solids are ___
A
Closely packed together
5
Q
What holds molecules together in solids?
A
Intermolecular forces
6
Q
Liquids have definite ___ but no definite ___
A
Definite volume, no definite shape
7
Q
Liquids have the ability to ___
A
Flow
8
Q
Molecules in liquids are ___
A
Very close together, but can flow past each other
9
Q
Intermolecular forces of liquids are strong enough to ___; not strong enough to ___
A
Strong enough to hold molecules in a condensed phase; not strong enough to prevent molecules from sliding past each other
10
Q
Gases have neither ___ nor ___
A
No definite shape or definite volume
11
Q
A gaseous sample will expand to ___
A
Fill the available space
12
Q
Intermolecular forces are ___ between gas molecules
A
Essentially zero
13
Q
Transitions between states of matter:
A
- Melting (S-L)
- Freezing (L-S)
- Vaporization (L-G)
- Condensation (G-L)
- Deposition (G-S)
- Sublimation (S-G)
14
Q
Deposition
A
Gas to solid
15
Q
Sublimation
A
Solid to gas
16
Q
What are intermolecular forces?
A
Chemical bonds hold atoms in molecules
17
Q
Intermolecular forces determine how molecules ___
A
Interact
18
Q
Intermolecular forces most directly impact ___
A
The macroscopic properties of a sample
19
Q
Repulsion of intermolecular forces
A
Molecules, atoms, and oppositely charged ions are attracted to each other, but not too close
20
Q
Intermolecular forces are ___ in nature
A
Electrostatic
21
Q
Coulomb’s Law
A
States that intermolecular forces arise because of the attraction of opposite charges
22
Q
The driving force in the formation of chemical bonds of all types is the ___
A
Octet rule
23
Q
Octet rule
A
Atoms tend to add, remove, or share electrons so as to wind up with eight valence electrons
24
Q
Valence electrons
A
Electrons in the highest energy, or valence shell
25
Noble gases each have a ___ valence shell
Filled, containing 8 electrons; located in group 8A
26
Ionic compounds are formed between ___ and ___
Metals and non metals
27
Metals don’t ___ their electrons very strongly; they are good ___; tend to form ___
Don’t hold onto their electrons very strongly; this is why they are good electrical conductors; tend to form cations
28
Nonmetals are much better at ___ electrons; tend to form ___
Attracting electrons; tend to form anions
29
Ionic bond
Results from coulombic attraction between oppositely charged ions
30
In the solid state, oppositely charged ions settle into a ___, in which every cation is attracted to every anion
Highly organized crystalline lattice
31
Ionic bonds are generally stronger than ___
Covalent bonds
32
Ionic compounds are (almost) always ___ under normal conditions
Solids
33
Example of an ionic compound:
NaCl
34
Valence bond theory—a covalent bond results from ___
Overlap of two electron clouds, electron sharing
35
Valence bond theory—electron is bound to the ___ because the negatively charged electron is attracted to the positively charged nucleus by Coulomb’s Law
Nucleus
This allows the electron on atom 1 to spend time around atom 2’s nucleus, and vice versa
36
VESPR Theory
The intermolecular forces that operate between the molecules in a sample, all of which are caused by how electrons are arranged in the molecule
37
Non-polar bond
If two atoms of identical electronegativity are bonded together
38
Polar bond
If two atoms of different electronegativity are bonded together; the electrons spend more time around the more electronegative atom; this creates partial charges
39
The greater the difference in electronegativity between two atoms, the more ___ the bond
Polar
40
Intermolecular forces are attractive forces between ___ or ___ or ___
Molecules or atoms or ions
41
Intermolecular forces are immensely important because these forces hold...
DNA molecules in a helix and are the mechanism for DNA transcription
42
Three main varieties of IM forces:
- Dipolar
- Hydrogen bonding
- London forces
43
Dipole-dipole attraction
This is the attraction between the opposite (partial) charges of polar molecules
44
Dipolar attractions occur only between
Polar molecules
45
Hydrogen bonding
Hydrogen bonds
46
London forces are generally the ___ of the three intermolecular forces
Weakest
47
All common matter experiences ___
London forces
48
A London force is the result of...
An instantaneous dipole that is created wherever electrons in a molecule are unevenly distributed
49
___ molecules show more London forces because ___ molecules have more ___
Larger molecules because large molecules have more electrons
50
London forces are AKA
Van der waals forces
51
More intermolecular forces mean— ___ boiling and melting points; ___ heats of fusion and vaporization; ___ vapor pressure; ___ viscous liquids
Higher boiling and melting points; higher heats of fusion and vaporization; lower vapor pressure; more viscous liquids
52
IM forces also affect ___
Solubility—“like dissolves like”
53
Substances with greater intermolecular attractions have ___ surface tensions
Greater
54
What is surface tension?
Molecules in the liquid state are attracted to all neighboring molecules by intermolecular forces
A molecule near the surface experiences attractive forces to all of the surrounding surface molecules and with the molecules below it in the liquid
Unbalanced forces create a “skin” on the surface of a liquid
The attractive strength of this skin is called the surface tension
55
LaPlace’s law—surface tension on a blood vessel wall will depend on the ___ of the vessel
Radius
56
LaPlace’s Law—the tension on the surface of the blood vessel is directly proportional to the ___ of the vessel
Radius
57
Aneurysms
Spherical
Represent a dangerous physical means for lowering the surface tension on a blood vessel
58
Tension for cylinders (LaPlace’s Law)
T = Pr
T = wall tension, P = pressure of fluid within the cylinder, r = radius
59
Tension for spheres (LaPlace’s Law)
T = Pr/2
60
Surfactants improve a solvent’s ability to be a solvent by reducing the ___
Surface tension of the solvent
61
Surfactant =
Surface active agent; commonly known as soaps or detergents
62
Soaps are derived directly from ___ or ___ through a chemical process called
Fats or oils (triglycerides) through a chemical process called saponification
63
A triglyceride is a triester derived from ___ and three ___
Glycerin and 3 fatty acids
64
A fatty acid is a long-chained carboxylic acid having ___ to ___ carbon atoms
12 to 18
65
Heating a fat or oil with excess sodium hydroxide gives 3 moles of a ___ plus 1 mole of ___
3 moles of a fatty acid salt, plus 1 mole of glycerin
66
A soap is the ___
Salt of a fatty acid
67
Detergent
Chemically synthesized, most commonly from soaps
Molecular structure can be tweaked to optimize the physical properties of the detergent
Can be positively or negatively charged, or uncharged
68
Surfactant molecules stick their polar heads onto ___ while their greasy tails ___
Polar heads onto water; greasy tails stick out of the surface of the water
69
Bilayer
Basic structure of cell membranes
Tails of surfactant molecules can dissolve in each other to form a double layer
Non polar tails interact with each other, with the polar heads on the outside interacting with the water molecules
70
Micelles
Tails can dissolve in each other forming a sphere; this creates a non-polar micro environment in the water
71
Viscosity is a measure of...
A fluid’s resistance to flow
72
Viscosity increases with ___
Increasing intermolecular forces
73
Substances having greater intermolecular forces have ___ vapor pressures
Lower
74
What is vapor pressure?
The most energetic molecules in a liquid have sufficient kinetic energy to break intermolecular forces and escape into the gas phase; once the molecules are free as gases, they exert a pressure, known as the vapor pressure
75
Vapor pressure and volatility of a liquid increases with ___ temperature
Increasing temperature
76
At the surface of a liquid, the most energetic molecules can escape from the IM forces into the ___ phase
Gas
77
Gas molecules near the surface of a liquid can be captured by IM forces into the ___ state
Liquid
78
When there is a balance between vaporization and condensation, a state of ___ exists
Dynamic equilibrium
79
Volatility is the tendency of a liquid to ___
Evaporate
80
Does a more volatile liquid have a higher or lower vapor pressure?
Higher vapor pressure
81
Does a more volatile liquid have a higher or lower boiling point?
Lower boiling point
82
Boltzmann distribution
Explains why vapor pressure increases with increasing temperature
83
Vapor pressures at 200C of common inhalational anesthetics—isoflurane
239 mm Hg
84
Enflurane
175 mm Hg
85
Halothane
243 mm Hg
86
Desflurane
669 mm Hg
87
Sevoflurane
157 mm Hg
88
Solid to liquid
Melting
89
Liquid to solid
Freezing
90
Liquid to gas
Vaporization
91
Gas to liquid
Condensation
92
Solid to gas
Sublimation
93
Gas to solid
Deposition
94
Boiling point
The temperature at which the vapor pressure of a liquid equals the ambient pressure
95
The normal boiling point is the temperature at which the vapor pressure of a liquid equals exactly ___
760 mm Hg
96
Compounds with more intermolecular forces have ___ boiling points
Higher
97
Molecules in the liquid state have sufficient intermolecular attractions to keep them from flying away from each other into the ___
Gas state
98
Compounds with more intermolecular forces have ___ melting temperatures
Higher
99
Melting point
The temperature at which the solid state reversibly passes into the liquid state
100
Solid state is characterized by...
Definite shape and volume, which is due to strong intermolecular forces that lock the component molecules into a crystalline array
101
Liquid state
Component molecules have sufficient intermolecular attractions to keep them from flying away from each other into the gas state, but the intermolecular forces are not strong enough to prevent the molecules from sliding around past each other
102
Molar enthalpy of vaporization
The heat required to convert 1 mole of a liquid to a gas at its normal boiling point
103
The molar enthalpy of vaporization is inherently ___, representing an amount of energy that must be added to the sample in order for the phase transition to occur
Endothermic
104
Molar enthalpy of vaporization represents the energy needed to ___ intermolecular forces and allow molecules to escape into the ___ phase
Break intermolecular forces; allow molecules to escape into the gas phase
105
Molar enthalpy of fusion
The heat necessary to convert 1 mole of a solid into a liquid at its normal melting point
106
Fusion is an inherently ___ process
Endothermic
107
Units for molar enthalpy of fusion
KJ/mole
108
The heat of fusion represents the amount of energy necessary to overcome the intermolecular forces to the point that the molecules can start to ___
Move around each other
109
A phase diagram shows combined effects of ___ and ___ on the state of matter
Temperature and pressure
110
3 key points of phase diagrams:
- Equilibrium lines between states
- Triple point
- Critical point
