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college chem 117 > midterm exam 4 > Flashcards

midterm exam 4 Flashcards

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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
Q

what do bonds do all the time

A

vibrate, bend, and stretch about 100000000000000 times per second

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26
Q

In pure water, [OH-] = [H+], and the solution is said to be

A

neutral

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27
Q

about how many moles of H2O is in 1 L of water

A

about 55 moles

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28
Q

what fraction of molecules dissociate in 1 L of water

A

about 2 in 1 billion

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29
Q

what does pH equal (mathematically)

A

-log[H+]

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30
Q

Many compounds that dissolve in water change the balance between H+ and OH- (i.e., they change the pH). These compounds are called ______

A

acids or bases

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31
Q

alkaline/basic solutions represent

A

[OH-] > [H+] ; pH > 7

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32
Q

acidic solutions represent

A

[H+] > [OH-] ; pH < 7

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33
Q

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.

A

extremely tightly

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34
Q

______ from normal pH makes a delicate machinery fall apart.

A

Small deviations

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35
Q

in our blood, Values greater than ___ or lower than ___ result in death

A

7.8; 6.8

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36
Q

what you eat has _____ effect on the acid concentrations in your blood

A

very little

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37
Q

what did Robert Young claim in his book “The pH Miracle” and what was his practice later called

A

claimed that diseases were caused by acidity in the blood; called quakery

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38
Q

why is HCl a strong acid

A

it dissociates completely when dissolved in water

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39
Q

do all hydrogens in a molecule have to be acidic

A

no

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40
Q

do all acids contain a hydrogen

A

no

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41
Q

what happens if you dissolve a very strong electrolyte in water?

A

it will be acidic

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42
Q

why is NaOH a strong base

A

it dissociates completely when dissolved in water

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43
Q

do all bases contain OH-

A

no

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44
Q

Reactions between an acid and a base are called _____

A

neutralization reactions

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45
Q

The reactions in which electrons are transferred from one reactant to the other are called ______

A

oxidation–reduction reactions

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46
Q

Atoms that lose electrons are being ____. The reaction is referred to as _____.

A

oxidized; oxidation

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47
Q

Atoms that gain electrons are being _____. The reaction is referred to as ______.

A

reduced; reduction

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48
Q

A reducing agent causes another substance to be reduced. During the reaction, the reducing agent is _____

A

oxidized

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49
Q

An oxidizing agent causes another substance to be oxidized. During the reaction, the oxidizing agent is _____

A

reduced

50
Q

Chemists assign a number to each element in a reaction, called an ______, that allows them to determine the electron flow in the reaction.

A

oxidation state (or oxidation number)

51
Q

Reduction occurs when an atom has gained electrons, resulting in _______ in the oxidation state of that atom.

A

a decrease

52
Q

Oxidation occurs when an atom has lost electrons, resulting in _______ in the oxidation state of that atom.

A

an increase

53
Q

strength of dispersion forces

A

.05-20 kJ/mol

54
Q

strength of dipole-dipole forces

A

3-20 kJ/mol

55
Q

strength of hydrogen bonding forces

A

10-40 kJ/mol

56
Q

strength of ion-dipole forces

A

30-100 kJ/mol

57
Q

how do particles move

A

randomly

58
Q

Gas particles move in _____ until they collide with either the container wall or another particle.

A

straight lines

59
Q

what do collisions exchange

A

momentum

60
Q

Particles (atoms or molecules) exert a force when they collide with the surface of the container. This is measured as the ______

A

pressure of the gas

61
Q

what are two things that you must assume with gases

A
  • 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
Q

what is true about gases under the two conditions

A

all gasses are the same, it doesn’t matter the size or polarity

63
Q

_______ is a tiny point that moves around without interacting with other molecules in the container (except for elastic collisions).

A

A molecule of an ideal gas

64
Q

Gas particles move in _____ until they collide with either the container wall or another particle

A

straight lines

65
Q

Larger molecules move _____ on average

A

slower

66
Q

molecules _____ velocity when they collide with other molecules but they _______ velocity when they collide with the walls

A

change; keep the same

67
Q

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

A

1 hour

68
Q

The average velocity of all molecules is related to _____

A

temperature

69
Q

what is a measure of the average kinetic energy (and therefore velocity) of the molecules

A

temperature

70
Q

what is the force that collisions exert

A

pressure

71
Q

All other variables being equal, which weight particles and molecules that move faster or slower will exert a larger pressure?

A

heavier particles and faster molecules

72
Q

what is the SI unit of volume

A

m^3

73
Q

what is the SI unit of velocity

A

m/s

74
Q

what is Kinetic Energy

A

Energy of a body due to its motion

75
Q

Kinetic Energy formula

A

Ek = (1/2)mv^2

76
Q

do temperature questions at home to practice

A

okay

77
Q

Collisions between two molecules will generally result in an exchange of _____. The total energy is _______.

A

kinetic energy; conserved

78
Q

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.

A

average velocity

79
Q

different molecules travel at ______

A

different velocities

80
Q

as temperature increases, kinetic energy______

A

increases

81
Q

kinetic energy for a molecule of gas

A

Ek = (3/2)kT

82
Q

in gases, Attractions between molecules are ______

A

neglected

83
Q

average kinetic energy formula

A

Ek = (1/2)m(v^2)av

84
Q

if two gasses have the same kinetic energy, which gas will move slower the heavier or the lighter gas

A

heavier

85
Q

If we use the mass of a molecule, we calculate the average kinetic energy of a molecule over a ____ period of time

A

long

86
Q

If we use the molar mass we calculate the average kinetic energy for a mole of gas molecules at ______ time

A

any given

87
Q

average kinetic energy of a mol of gas

A

Ek = (3/2)RT

88
Q

using the formula for average kinetic energy, it is not exactly average velocity, what is it?

A

root‐mean‐square velocity (rms velocity)

89
Q

root‐mean‐square velocity, gives ________ of the average, but is not an average

A

an estimate

90
Q

The rms velocity is _______ on the graph than the most probable velocity which is at the peak

A

a little further past

91
Q

If we grab a molecule randomly, the most probable velocity is the ______. The average velocity of all molecules is ______.

A

peak of this distribution; higher

92
Q

what are the three things that pressure depends on

A

The average number of collisions per unit area
The mass of the particle (molecule/atom)
The velocity of the particles

93
Q

More particles results in ____ pressure and more collisions

A

higher

94
Q

If volume is smaller and the same amount of particles remain, there are ____ collisions so pressure _____

A

more; increases

95
Q

Pressure increases with increasing _____ Pressure decreases with increasing ___

A

n and T; V

96
Q

The behavior of a gas is more likely to be well‐described by the ideal gas model at _____ densities

A

low

97
Q

The magnitude of the attractive force depends on ____

A

distance.

98
Q

At low densities the average distance between two molecules is _____

A

larger

99
Q

at high densities, molecules are _______

A

closer together

100
Q

____ behavior is what happens in reality

A

Real

101
Q

_____ 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

A

Ideal

102
Q

With a molecule that has strong _______ forces the Pideal is larger than the Preal

A

attractive

103
Q

why is the Pideal larger than the Preal with attractive forces?

A

the attractive forces hold the molecules closer together so they hit the container less resulting in a smaller pressure than the ideal

104
Q

Attractive interactions are _____ energies

A

negative

105
Q

negative energies make atoms _____ stable

A

more

106
Q

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

A

repulsive force

107
Q

do larger or smaller molecules experiences the strongest attractive interactions between molecules?

A

larger

108
Q

ideal gasses have ____ attraction and size

A

no

109
Q

an expression that relates p, V, T, and n

A

equation of state

110
Q

_______ 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.

A

density

111
Q

The lower the density, the _____ the intermolecular interactions

A

weaker

112
Q

As density increases, pressure _____

A

decreases

113
Q

______ states that the total pressure of a gas mixture is the sum of the partial pressures

A

Dalton’s law

114
Q

The pressure of a single gas in a mixture of gases is called its _______

A

partial pressure.

115
Q

The partial pressure from the ideal gas law can be determined by assuming that each gas
component acts _____

A

independently

116
Q

The number of moles of a component in a mixture divided by the total number of moles in
the mixture is the _____

A

mole fraction

117
Q

how do you calculate the partial pressure of a gas

A

multiply the total pressure by the mole ratio of a certain gas

118
Q

what is the main thing density determines

A

average distance

119
Q

P_____ will always be larger than P______ when there is attractive forces

A

ideal; real

120
Q

if the molecules get very close together, from an extremely high densities, whats larger Pideal or Preal?

A

Preal

121
Q

attractive forces ______ energy

A

lowers

122
Q

repulsive forces _______ energy

A

raises

college chem 117 (7 decks)

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