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college chem 117 > midterm exam 4 > Flashcards

midterm exam 4 Flashcards

(122 cards)

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1
Q

Materials that dissolve in water to form a solution that will conduct electricity are called

A

electrolytes

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2
Q

NaCl dissolves in water, and the charged ions conduct what

A

electricity

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3
Q

NaCl is a _______ electrolyte because it dissociates completely in water

A

strong

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4
Q

if an ionic compound doesn’t dissolve in water, can it still be regarded as an electrolyte?

A

no

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5
Q

Interactions between Na+ and Cl‐ are ______

A

electrostatic

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6
Q

Materials that dissolve in water to form a solution that will not conduct electricity are called?

A

nonelectrolytes

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7
Q

Sucrose dissolves in water, but its __________ do not conduct electricity.

A

neutral molecules

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8
Q

Acetic Acid is a molecule that partially dissociates into ions when dissolved in water. It is a _____ electrolyte.

A

weak

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9
Q

non electrolytes have ___ dissociation

A

no

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10
Q

weak electrolytes have ___ dissociation

A

partial

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11
Q

strong electrolytes have ___ dissociation

A

complete

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12
Q

is silver nitrate a strong or weak electrolyte

A

strong

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13
Q

is silver chloride a strong or weak electrolyte

A

very weak, almost a nonelectrolyte because it is almost completely insoluble

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14
Q

Attractive forces hold together the ions/molecules of solute in the crystal. What must be done for the solute to dissolve? What happens after?

A

These attractive interactions need to be broken; new attractive forces will be established between the solute ions/molecules and the solvent

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15
Q

A precipitation reaction is one where aqueous solutions of ionic compounds are mixed to produce an ionic compound that is insoluble in water.
The insoluble product is called what?

A

a precipitate

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16
Q

What happens when we mix a solution of NaCl with a solution of KI?

A

Neither NaI nor KCl precipitate because they are both soluble salts

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17
Q

An equation showing the complete neutral formula for each compound in the aqueous reaction as if they existed as molecules is called what?

A

a molecular equation

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18
Q

In actual solutions of soluble ionic compounds, dissolved substances are present as ions. Equations that describe the material’s structure when dissolved are called what?

A

complete ionic equations

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19
Q

A ________ differs from a complete ionic equation because it does NOT have spectator ions (K+, NO3‐) in the equation.

A

net ionic equation

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20
Q

What is the maximum amount of solute that can dissolve in a given amount of solvent at a given temperature

A

Solubility

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21
Q

A solution is said to be ______ when its concentration equals the solubility

A

saturated

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22
Q

A solution is said to be ______ when its concentration is lower than the solubility.

A

undersaturated

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23
Q

A solution is said to be ______ when its concentration is higher than the solubility

A

supersaturated

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24
Q

understand solubility graphs

A

okay

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25
what do bonds do all the time
vibrate, bend, and stretch about 100000000000000 times per second
26
In pure water, [OH-] = [H+], and the solution is said to be
neutral
27
about how many moles of H2O is in 1 L of water
about 55 moles
28
what fraction of molecules dissociate in 1 L of water
about 2 in 1 billion
29
what does pH equal (mathematically)
-log[H+]
30
Many compounds that dissolve in water change the balance between H+ and OH- (i.e., they change the pH). These compounds are called ______
acids or bases
31
alkaline/basic solutions represent
[OH-] > [H+] ; pH > 7
32
acidic solutions represent
[H+] > [OH-] ; pH < 7
33
Our body regulates pH _____ because most of the biochemical reactions that our cells undergo continuously are very sensitive to pH. The structure of proteins and the interactions between proteins and nucleic acids can also be very sensitive to pH.
extremely tightly
34
______ from normal pH makes a delicate machinery fall apart.
Small deviations
35
in our blood, Values greater than ___ or lower than ___ result in death
7.8; 6.8
36
what you eat has _____ effect on the acid concentrations in your blood
very little
37
what did Robert Young claim in his book "The pH Miracle" and what was his practice later called
claimed that diseases were caused by acidity in the blood; called quakery
38
why is HCl a strong acid
it dissociates completely when dissolved in water
39
do all hydrogens in a molecule have to be acidic
no
40
do all acids contain a hydrogen
no
41
what happens if you dissolve a very strong electrolyte in water?
it will be acidic
42
why is NaOH a strong base
it dissociates completely when dissolved in water
43
do all bases contain OH-
no
44
Reactions between an acid and a base are called _____
neutralization reactions
45
The reactions in which electrons are transferred from one reactant to the other are called ______
oxidation–reduction reactions
46
Atoms that lose electrons are being ____. The reaction is referred to as _____.
oxidized; oxidation
47
Atoms that gain electrons are being _____. The reaction is referred to as ______.
reduced; reduction
48
A reducing agent causes another substance to be reduced. During the reaction, the reducing agent is _____
oxidized
49
An oxidizing agent causes another substance to be oxidized. During the reaction, the oxidizing agent is _____
reduced
50
Chemists assign a number to each element in a reaction, called an ______, that allows them to determine the electron flow in the reaction.
oxidation state (or oxidation number)
51
Reduction occurs when an atom has gained electrons, resulting in _______ in the oxidation state of that atom.
a decrease
52
Oxidation occurs when an atom has lost electrons, resulting in _______ in the oxidation state of that atom.
an increase
53
strength of dispersion forces
.05-20 kJ/mol
54
strength of dipole-dipole forces
3-20 kJ/mol
55
strength of hydrogen bonding forces
10-40 kJ/mol
56
strength of ion-dipole forces
30-100 kJ/mol
57
how do particles move
randomly
58
Gas particles move in _____ until they collide with either the container wall or another particle.
straight lines
59
what do collisions exchange
momentum
60
Particles (atoms or molecules) exert a force when they collide with the surface of the container. This is measured as the ______
pressure of the gas
61
what are two things that you must assume with gases
* The volume occupied by the molecules is negligible compared to the volume of the container * Molecules do not interact with each other (other than elastic collisions)
62
what is true about gases under the two conditions
all gasses are the same, it doesn't matter the size or polarity
63
_______ is a tiny point that moves around without interacting with other molecules in the container (except for elastic collisions).
A molecule of an ideal gas
64
Gas particles move in _____ until they collide with either the container wall or another particle
straight lines
65
Larger molecules move _____ on average
slower
66
molecules _____ velocity when they collide with other molecules but they _______ velocity when they collide with the walls
change; keep the same
67
when a gas is displaced, the molecules are moving back and forth very fast, so it takes about _____ to make it 1 meter in one direction
1 hour
68
The average velocity of all molecules is related to _____
temperature
69
what is a measure of the average kinetic energy (and therefore velocity) of the molecules
temperature
70
what is the force that collisions exert
pressure
71
All other variables being equal, which weight particles and molecules that move faster or slower will exert a larger pressure?
heavier particles and faster molecules
72
what is the SI unit of volume
m^3
73
what is the SI unit of velocity
m/s
74
what is Kinetic Energy
Energy of a body due to its motion
75
Kinetic Energy formula
Ek = (1/2)mv^2
76
do temperature questions at home to practice
okay
77
Collisions between two molecules will generally result in an exchange of _____. The total energy is _______.
kinetic energy; conserved
78
A given molecule changes its velocity in each collision. Sometimes the velocity will increase, and sometimes it will decrease. At a given temperature, its ______ will be constant.
average velocity
79
different molecules travel at ______
different velocities
80
as temperature increases, kinetic energy______
increases
81
kinetic energy for a molecule of gas
Ek = (3/2)kT
82
in gases, Attractions between molecules are ______
neglected
83
average kinetic energy formula
Ek = (1/2)m(v^2)av
84
if two gasses have the same kinetic energy, which gas will move slower the heavier or the lighter gas
heavier
85
If we use the mass of a molecule, we calculate the average kinetic energy of a molecule over a ____ period of time
long
86
If we use the molar mass we calculate the average kinetic energy for a mole of gas molecules at ______ time
any given
87
average kinetic energy of a mol of gas
Ek = (3/2)RT
88
using the formula for average kinetic energy, it is not exactly average velocity, what is it?
root‐mean‐square velocity (rms velocity)
89
root‐mean‐square velocity, gives ________ of the average, but is not an average
an estimate
90
The rms velocity is _______ on the graph than the most probable velocity which is at the peak
a little further past
91
If we grab a molecule randomly, the most probable velocity is the ______. The average velocity of all molecules is ______.
peak of this distribution; higher
92
what are the three things that pressure depends on
The average number of collisions per unit area The mass of the particle (molecule/atom) The velocity of the particles
93
More particles results in ____ pressure and more collisions
higher
94
If volume is smaller and the same amount of particles remain, there are ____ collisions so pressure _____
more; increases
95
Pressure increases with increasing _____ Pressure decreases with increasing ___
n and T; V
96
The behavior of a gas is more likely to be well‐described by the ideal gas model at _____ densities
low
97
The magnitude of the attractive force depends on ____
distance.
98
At low densities the average distance between two molecules is _____
larger
99
at high densities, molecules are _______
closer together
100
____ behavior is what happens in reality
Real
101
_____ behavior is a simplified formalism in which molecules are assumed to have negligible size and move around the container without interacting with each other except for elastic collisions
Ideal
102
With a molecule that has strong _______ forces the Pideal is larger than the Preal
attractive
103
why is the Pideal larger than the Preal with attractive forces?
the attractive forces hold the molecules closer together so they hit the container less resulting in a smaller pressure than the ideal
104
Attractive interactions are _____ energies
negative
105
negative energies make atoms _____ stable
more
106
If you try to get the atoms closer together than the min (2 times the radii in A) energy, it becomes a ________ and the energy shoots up
repulsive force
107
do larger or smaller molecules experiences the strongest attractive interactions between molecules?
larger
108
ideal gasses have ____ attraction and size
no
109
an expression that relates p, V, T, and n
equation of state
110
_______ is a measure of how many molecules we have in given volume, which in turn measures how close molecules are on average to each other.
density
111
The lower the density, the _____ the intermolecular interactions
weaker
112
As density increases, pressure _____
decreases
113
______ states that the total pressure of a gas mixture is the sum of the partial pressures
Dalton’s law
114
The pressure of a single gas in a mixture of gases is called its _______
partial pressure.
115
The partial pressure from the ideal gas law can be determined by assuming that each gas component acts _____
independently
116
The number of moles of a component in a mixture divided by the total number of moles in the mixture is the _____
mole fraction
117
how do you calculate the partial pressure of a gas
multiply the total pressure by the mole ratio of a certain gas
118
what is the main thing density determines
average distance
119
P_____ will always be larger than P______ when there is attractive forces
ideal; real
120
if the molecules get very close together, from an extremely high densities, whats larger Pideal or Preal?
Preal
121
attractive forces ______ energy
lowers
122
repulsive forces _______ energy
raises

college chem 117 (7 decks)

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