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MCAT Chem Flashcards

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1
Q

What are valence electrons?

A

The electrons farthest from the nucleus, as well as any electrons available for bonding, are the valence electrons

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2
Q

T/F: One amu is equal to 1/12 the mass of a carbon-12 atom

A

True

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3
Q

How many particles are in a mole (mol)?

A

1 mol = 6.022 x 10 23 power

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4
Q

What is atomic weight?

A

The atomic weight of an element reflects the number of grams per mole (g/mol) of the element. The atomic weight is usually derived from a weighted average of the naturally occurring isotopes of the element.

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5
Q

What is an isotope?

A

An isotope is a different form of the same element due to a different number of neutrons

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6
Q

What is Planck’s constant?

A

6.626 x 10 -34 power m 2power kg/s

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7
Q

How many more protons are in a carbon - 14 atom than in a carbon - 12 atom?

A

None. Carbon-12 and carbon-14 are isotopes. They thus have the same number of protons

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8
Q

What is an atomic emission spectrum?

A

An atomic emission spectrum is the unique spectrum of light emitted when an atom’s electrons fall to their ground states.

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9
Q

What is an atomic absorption spectrum?

A

An atomic absorption spectrum is the unique spectrum of light absorbed when an atom’s electrons are excited to higher energy levels

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10
Q

Define the Heisenberg uncertainty principle

A

The Heisenberg uncertainty principle states that it is impossible to know both the momentum and position of an electron at the same time.

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11
Q

Define the Pauli exclusion principe

A

The Pauli exclusion principle states taht no two electrons in an atom can have the same four quantum numbers

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12
Q

What does the principal (1st) quantum number (n) represent?

A

The principal (1st) quantum number (n) is an integer which represents the shell (energy level) of an electron

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13
Q

What is the maximum number of electrons allowed in the second shell (n=2)?

A

The max number of electrons in the second shell is eight. (The maximum number of electrons in any shell equals 2n 2(power)

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14
Q

What does the azimuthal (2nd) quantum number (l) represent?

A

The azimuthal (2nd) quantum number (l) represents the subshell

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15
Q

What are the first 4 subshells (corresponding to l=0, 1, 2, and 3)?

A

first four subshells are: s,p,d, and f

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16
Q

What is the formula for the maximum number of electrons allowed in a subshell?

A

Maximum number of electrons in a subshell = (4l +2)

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17
Q

What does the magnetic 3rd quantum number (m sub l) represent?

A

The third quantum number represents an orbital within a subshell. The possible values range from -l to l

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18
Q

How many fourth quantum numbers (m sub s) are possible for an electron? What are they?

A

The two possible values for m sub s are +1/2 and -1/2

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19
Q

What is Hund’s Rule

A

Hund’s Rule states that electrons will fill to create the maximum number of half-filled orbitals

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20
Q

Which subshell will fill first? 5s or 3d

A

3d will fill before 5s Note: compare (n+l) values. The lower sum has lower energy If the sums are equal, the subshell with the lower n value will fill first.

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21
Q

Which subshell will fill first? 6s or 4f

A

6s will fill before 4f Note: compare (n+l) values. The lower sum has lower energy If the sums are equal, the subshell with the lower n value will fill first.

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22
Q

Which subshell will fill first? 4p or 3d

A

3d will fill before 4p Note: compare (n+l) values. The lower sum has lower energy If the sums are equal, the subshell with the lower n value will fill first.

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23
Q

What is a paramagnetic material

A

Paramagnetic material has unpaired electrons

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24
Q

what is a diamagnetic material

A

Diamagnetic material has no unpaired electrons

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25
Q

Does a “period” run horizontally or vertically?

A

A period runs horizontally

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26
Q

Does a “group” run horizontally or vertically?

A

A group runs vertically

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27
Q

T/F: Groups have the same valence configuration and have similar chemical properties

A

True

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28
Q

Which group (A or B) contains the representative elements?

A

Group A elements are the representative elements

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29
Q

Which group of elements (A or B) contains the transition elements?

A

Group B elements are the transition elements

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30
Q

What happens to the number of electrons when one moves from left to right across a row?

A

Electrons are sequentially added as you move across a row

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31
Q

Are electrons more tightly held or less tightly held as one moves down a column?

A

Electrons are less tightly held as you moved down a column

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32
Q

What is the atomic radii trend within the periodic table?

A

Atomic radii decrease as you move from left to right across a period and up a group

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33
Q

What is ionization energy (L.E.)?

A

Ionization energy is the energy required to completely remove an electron from an atom

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34
Q

What is the ionization energy trend within the periodic table?

A

I.E. increases as you move from left to right across a period and up a group

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35
Q

Compare the values of the first ionization and second ionization energy of an atom

A

The second ionization energy is always higher than the first ionization energy of an atom

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36
Q

What is electron affinity?

A

Electron affinity is the energy released when an atom accepts an electron

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37
Q

What is the electron affinity trend within the periodic table?

A

Electron affinity increases as you move from left to right across a period and up a group

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38
Q

T/F: Group VIIIA elements have high electron affinities

A

False, Group VIIIA elements have a stable octet and have an electron affinity approaching zero

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39
Q

What is electronegativity?

A

Electronegativity is a measure of the attraction an atom has for electrons in a chemical bond

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40
Q

What is the electronegative trend within the periodic table?

A

Electronegativity increases as you move from left to right across a period and up a group

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41
Q

T/F: Metals are found on the left side of the periodic table and are good conductors of electricity and heat

A

True

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42
Q

T/F: Nonmetals are found in the middle of the periodic table and are malleable, ductile, and shiny

A

False, nonmetals are generally brittle and lusterless, and are located on the upper right side of the periodic table

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43
Q

T/F: Metalloids are found between the metals and nonmetals and have varying properties

A

True

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44
Q

Which group of elements contains the alkali metals?

A

Group 1A elements are known as the alkali metals

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45
Q

Which group of elements contains the halogens?

A

Halogens are in group VIIA

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46
Q

Which group of elements contains the alkaline earths?

A

The alkaline earths are in group IIA

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47
Q

Which group of elements contains the noble gases?

A

The noble gases are in group VIIIA

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48
Q

Which group of elements contains the transition metals?

A

The transition metals are in groups 1B to VIIIB

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49
Q

What is an ionic bond

A

An ionic bond is formed from the transfer of electrons between two atoms

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50
Q

What is a covalent bond

A

A covalent bond is formed from the sharing of electrons between atoms

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51
Q

What is a polar covalent bond?

A

A polar covalent bond is one that has properties of both ionic and covalent bonds. Electrons are shared, but not equally

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52
Q

What is a cation?

A

A cation is a positively charged ion

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53
Q

What is an anion?

A

An anion is a negatively-charged ion

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54
Q

Which type of bond forms between two atoms with substantial differences in electronegativities (>1.7)?

A

Ionic bonds forms between two atoms with substantial differences in electronegativities

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55
Q

T/F: All atoms bond according to the “octet rule”

A

False, some atoms such as hydrogen can have only two valence electrons while others can have more than eight

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56
Q

What are some characteristics of ionic compounds?

A

Ionic compounds form crystal lattices, conduct electricity in solution, and have high melting and boiling points

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57
Q

What are the bond orders of single, double, and triple bonds?

A

1st order 2nd order 3rd order

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58
Q

T/F: A triple bond is longer than a single bond.

A

False, a triple bond is shorter than a single bond

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59
Q

What is bond energy?

A

Bond energy is the amount of energy required to separate two bonded atoms

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60
Q

Can both bonding and nonbonding electrons be valence electrons?

A

Yes, they can both be valence electrons. Nonbonding electrons are not involved in a bond, whereas bonding electrons are involved in a bond.

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61
Q

What is the formula for calculating formal charge on an atom involved in a covalent bond?

A

Formal charge = V - (1/2 N bonding + N nonbonding)

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62
Q

What are resonance structures?

A

Two or more non-identical Lewis structures for the same molecule are resonance structures

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63
Q

T/F: A Lewis structure with small or no formal charges is preferred over one with large formal charges

A

True

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64
Q

Should a negative formal charge be placed on highly electronegative atoms or weakly electronegative atoms?

A

Negative formal charge should be placed on highly electronegative atoms

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65
Q

Which type of bond forms between atoms with small differences in electronegativity (.4 - 1.7)?

A

polar covalent bond forms between atoms with small differences in electronegativity

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66
Q

Which type of bond forms between atoms with the same electronegativities?

A

A nonpolar covalent bond forms between atoms with the same electronegativities

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67
Q

What is a coordinate covalent bond?

A

A coordinate covalent bond is one in which a pair of bonding electrons originates from just one of the atoms

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68
Q

T/F: A dipole moment exists when a molecule has a separation of positive and negative charges

A

True

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69
Q

What are the 3 steps for determining geometric configuration?

A
  1. Draw Lewis Structure of the molecule 2. Count the bonding and nonbonding electron pairs in the valence shell of the central atom 3. Arrange the electron pairs around the central atom so that they are as far apart as possible
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70
Q

Can molecules with polar bonds be nonpolar?

A

Yes, if there is no net dipole moment within the molecule, it will be nonpolar

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71
Q

What is the shape of an s orbital?

A

An s orbital is spherical

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72
Q

What is the shape of a p orbital?

A

A p orbital is bi-lobed

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73
Q

What are three types of intermolecular forces?

A

The three types of intermolecular forces are: 1. dipole-dipole interactions 2. hydrogen bonding 3. dispersion forces

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74
Q

State the intermolecular forces in order of increasing strength

A

dispersion forces < dipole-dipole < hydrogen bonding

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75
Q

Which molecules, polar or nonpolar, typically have higher boiling points?

A

Polar molecules typically have higher boiling points

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76
Q

What is molar mass (molar weight)?

A

Molar mass is the number of grams per mole of a compound or an element

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77
Q

How many equivalents of hydrogen ion are in the following: HCL, H2SO4, H3PO4?

A

There are 1, 2, and 3 equivalents respectively

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78
Q

What is the formula for gram equivalent weight?

A

Gram Equivalent Weight= Molar Mass/n

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79
Q

What is the formula for calculating equivalents?

A

Equivalents = weight of compound/ gram equivalent weight

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80
Q

What is an empirical formula?

A

An empirical formula represents the simplest whole number ratio of the elements present in a compound

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81
Q

What is the empirical formula for C6H12O6

A

The empirical formula is CH2O

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82
Q

What is a molecular formula?

A

A molecular formula represents the actual number of atoms of each element present in a molecule of the compound

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83
Q

What is the formula for calculating percent composition?

A

% Composition = Mass of X in Compound/ MW of Compound x100%

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84
Q

A + X –> AX

A

Combination or addition

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85
Q

AX –> A + X

A

Decomposition

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86
Q

AX + BY –> AY + BX

A

double displacement

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87
Q

HA (aq) +BOH (aq) –> AB (aq) + H2O

A

Neutralization

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88
Q

AX + B –> BX + A

A

Single displacement

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89
Q

What is a limiting reagent?

A

limiting reagent is the reagent that is fully consumed in a reaction

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90
Q

What is theoretical yield?

A

Theorretical yield is the amount of product that can be predicted from a balanced equation

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91
Q

What is actual yield?

A

Actual yield is the amount of product actually isolated from the reaction experimentally

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92
Q

What is percent yield and what is the formula for calculating it?

A

Percent yield represents the relationship between actual yield and theoretical yield. Percent yield = Actual yield/ Theoretical yield x100%

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93
Q

What is an elementary reaction?

A

An elementary reaction is a reaction that cannot be decomposed into other reactions

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94
Q

T/F: A complex reaction can be broken down into two or more elementary reactions

A

True

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95
Q

What is an intermediate?

A

An intermediate is a complex that appears during the course of a reaction but does not appear in the net reaction, or as a final product

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96
Q

What is the rate determining step of a reaction?

A

The rate determining step is the slowest step of a reaction

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97
Q

What is the general formula for the rate law of the following reaction? aA + bB –> cC + dD

A

Rate = k[A] raised to x [B] raised to y

98
Q

T/F: Rate = -∆[reactants] / time or Rate = ∆[products] / time

A

True

99
Q

What is the reaction order for the following rate law? rate= k[A][B]2

A

Reaction order= 3 (x=1, y=2, and order = x+y)

100
Q

Is the rate of a zero order reaction dependent on the concentration of the reactants?

A

No, a zero order reaction has a constant rate that is independent of the concentration of reactants.

101
Q

What is the enthalpy change of a reaction?

A

Enthalpy change (∆H) of a reaction is the difference between the potential energy of the products and the potential energy of the reactants. ∆H= PE products - PE reactants

102
Q

How do increasing temperature and reactant concentration affect the rate of reaction?

A

Increasing temperature and reactant concentration increase the rate of most reactions

103
Q

Can the medium in which a reaction takes place affect the reaction rate?

A

Yes, the medium can affect the reaction rate

104
Q

How does a catalyst increase reaction rate?

A

A catalyst increases the reaction rate by decreasing the Ea

105
Q

Do pure solids or liquids appear in an equilibrium constant expression?

A

No, pure solids or liquids do not appear in an equilibrium constant expression

106
Q

Does Keq for a reaction remain constant at all temperatures?

A

No, Keq is characteristic of a given system at a given temperature

107
Q

If there is much more product than reactant at equilibrium, what can be said of Keq (as compared to 1)?

A

Keq would be greater than 1 Keq= [products] / [reactants]

108
Q

If Keq is very small compared to 1, then what can be said about the amount of reactants and products at equilibrium?

A

If Keq <1, there will be MORE reactants than products at equilibrium

109
Q

According to Le Chatelier’s Principle, in which direction will equilibrium shift if products are removed?

A

If products are removed, equilibrium will shift to favor the forward reaction

110
Q

What is an isolated system?

A

An isolated system cannot exchange energy or matter with its surroundings

111
Q

What is a closed system?

A

A closed system can exchange energy but cannot exchange matter with its surroundings

112
Q

What is an open system?

A

An open system can exchange both energy and matter with its surroundings

113
Q

What is an isothermal process?

A

An isothermal process is a process that occurs at constant temperature

114
Q

What is an isobaric process?

A

An isobaric process is a process that takes place at constant pressure

115
Q

What is an adiabatic process?

A

An adiabatic process is a process in which no heat exchange occurs between the system and the surroundings ∆Q = 0

116
Q

T/F: Heat absorbed by a system is considered positive and heat lost by a system is considered negative

A

True

117
Q

What is an endothermic process?

A

An endothermic process is a process that absorbs heats from the surroundings

118
Q

What is an exothermic process?

A

An exothermic process is a process that releases heat to the surroundings

119
Q

What is the formula for calculating heat (q) absorbed or released by a process?

A

q= (mass)(heat capacity)(∆ in Temperature q=mc∆T

120
Q

What is a formula for calculating ∆Hrxn

A

∆Hrxn=(sum of ∆Hsubf of products) - (sum of ∆Hsubf of reactants)

121
Q

Does a positive ∆H correspond to an endothermic or exothermic process?

A

A positive ∆H corresponds to an endothermic process.

122
Q

Does a negative ∆H correspond to an endothermic or exothermic process?

A

A negative ∆H corresponds to an exothermic process

123
Q

T/F: HEss’s Law states that enthalpies of reactions are additive

A

True

124
Q

If ∆H of a forward reaction is -220 kJ/mol, what is the ∆H of the reverse reaction?

A

the ∆H of the reverse reaction is +220 kJ/mol

125
Q

What is the bond dissociation energy?

A

Bond dissociation energy is the amount of energy required to break a particular bond in one mole of gaseous molecules

126
Q

What is entropy?

A

Entropy is the measure of disorder or randomness of a system

127
Q

When does a system reach maximum entropy?

A

Maximum entropy occurs when a system is at equilibrium

128
Q

What is the Gibb’s Free Energy equation? ∆G=

A

∆G = ∆H - T∆S

129
Q

How does the value of ∆G correlate with the spontaneity of a reaction?

A

∆G is negative for a spontaneous reaction ∆G is positive for a non-spontaneous reaction

130
Q

What is the value of ∆G for a system at equilibrium?

A

∆G at equilibrium = 0

131
Q

T/F: a reaction with (+) ∆H and a (-)∆S is always spontaneous

A

False, a reaction with a (+)∆H and a (-) ∆S is always non-spontaneous

132
Q

Under what conditions will a reaction with a (+) ∆H and a (+) ∆S be spontaneous?

A

At high temperatures, a reaction with a (+) ∆H and a (+) ∆S will be spontaneous

133
Q

Under what conditions will a reaction with a (-)∆H and a (-)∆S be spontaneous?

A

At low temperatures, a reaction with a (-)∆H and (-)∆S will be spontaneous

134
Q

What are the three phases of matter?

A

The three phases of matter are: solid, liquid, and gas

135
Q

What is standard pressure in atm, mm Hg and torr?

A

Standard pressure= 1atm = 760mm Hg = 760 torr

136
Q

What is standard temperature in Kelvin? Celsius?

A

Standard temperature =273.15K = 0 degrees C

137
Q

T/F: An ideal gas represents a hypothetical gas whose particles take up no volume and experience no intermolecular forces

A

True

138
Q

What is Boyle’s Law?

A

Boyle’s Law states that under isothermal conditions, pressure is inversely proportional to volume P1V1= P2V2

139
Q

What is Charles Law

A

Charles Law states that under constant pressure, volume is directly proportional to absolute temperature. V1/T1 = V2/T2

140
Q

T/F: Avogadro’s Principle states that at constant temperature and pressure, volume is directly proportional to the number of moles of gas

A

True

141
Q

What is the ideal gas law?

A

(pressure)(volume) = (moles)(gas constant)(temperature) PV= nRT

142
Q

What is the volume of 1 mole of gas at STP?

A

1 mole of gas occupies 22.4 liters at STP

143
Q

What are the typical units of density (for a gas)?

A

The units for density are g/L

144
Q

T/F: For a specific sample of gas, (P1V1)/T1 = (P2V2)/T2

A

True

145
Q

What is the formula for calculating the density of a gas? d=

A

d= m/V = P(MM)/RT

146
Q

Under what conditions is the ideal gas law more correct?

A

Gases behave in near-ideal fashion at low pressures and high temperatures

147
Q

How do actual volume and predicted volume of a gas compare at moderately high pressures? Extremely high pressures?

A

At moderately high pressures, a gas’s volume is less than would be predicted At extremely high pressures, a gas’s volume is more than would be predicted

148
Q

How do actual volume and ideal volume of a gas compare at very low temperatures?

A

At very low temperatures, actual volume is less than would be predicted

149
Q

What is Dalton’s Law of Partial Pressures?

A

Dalton’s Law of Partial Pressures states that the total pressure of a gaseous mixture is equal to the sum of the partial pressures of the individual components

150
Q

T/F: A gas molecule’s kinetic energy is inversely proportional to the absolute temperature of the gas

A

False, kinetic energy is directly proportional to absolute temperature

151
Q

T/F: The rates at which two gases diffuse are inversely proportional to the square root of their molar masses.

A

True

152
Q

What is effusion?

A

Effusion is the flow of gas particles under pressure from one container to another through a small opening

153
Q

T/F: The rates of effusion for two molecules are directly proportional to the square root of their molar masses.

A

False, the rates of effusion are inversely proportional just as in diffusion

154
Q

T/F: SOlids and liquids are often referred to as the condensed phases

A

True

155
Q

What does it mean when two liquids are immiscible?

A

Immiscible liquids repel each other and do not mix to form a solution

156
Q

What is an emulsion?

A

An emulsion is a mixture of immiscible liquids which are broken up into extremely small particles

157
Q

What is condensation? Evaporation?

A

Condensation occurs when gas changes to liquid. Evaporation occurs when liquid changes to gas

158
Q

What is fusion?

A

Fusion occurs when a solid changes to a liquid

159
Q

What is solidification (crystallization)?

A

Solidification or crystallization occurs when a liquid changes to a solid

160
Q

What is sublimation?

A

Sublimation occurs when a solid changes directly to a gas

161
Q

What is deposition?

A

Deposition occurs when a gas changes directly to a solid

162
Q

What is a colligative property?

A

A colligative property is a property derived solely from the number of particles present, not the nature of those particles

163
Q

Name the 4 colligative properties:

A

Freezing-point depression, boiling point elevation, osmotic pressure and vapor pressure lowering

164
Q

What is the formula for freezing-point depression? ∆T subf=

A

∆T sub f= K subf (molality of solution) = K sub f m

165
Q

What is the formula for boiling-point elevation? ∆T sub b=

A

∆T sub b= K subf (molality of solution) = K sub b m

166
Q

Is osmotic pressure proportional to molarity?

A

Yes, osmotic pressure is proportional to molarity

167
Q

What is the formula for osmotic pressure?

A

∏ = MRT = (Molarity)(Gas constant)(Temperature)

168
Q

What is an aqueous solution

A

An Aqueous Solution is one in which water is the solvent

169
Q

What is solubiility

A

Solubility is the measure of the amount of substance that can be dissolved in a particular solvent at a particular temperature

170
Q

What is a saturated solution?

A

A saturated solution contains the maximum amount of solute that can be dissolved in a particular solvent at a particular temperature

171
Q

T/F: Metals, which are on the left side of the periodic table, generally form positively charged ions. Non-metals on the right side generally form negatively-charged ions

A

True

172
Q

What is an electrolyte

A

An electrolyte is a solute whose solution is conductive

173
Q

What is the formula for percent composition by mass?

A

% = mass of solute/ mass of solution x100

174
Q

What is the definition of mole fraction (X)?

A

X = moles of compound/total number of moles

175
Q

What is the definition of molarity (M)?

A

M= moles of solute/liters of solution

176
Q

What is the definition of molality(m)?`

A

m= moles of solute/Kg of solvent

177
Q

What is the definition of normality (N)?

A

N= GEW of solute/liters of solution

178
Q

T/F: A solution which is diluted is related to its initial concentration as follows: MiVi = MfVf

A

True

179
Q

What is the difference between I.P. and Ksp?

A

I.P. is defined with respect to initial concentrations. Ksp is defined with respect to the concentrations of a saturated solution at equilibrium

180
Q

If the ion product (I.P.) is larger than the solubility product constant (Ksp), is the solution saturate, unsaturated, or supersaturated?

A

If I.P. > Ksp then the solution is supersaturated

181
Q

If the I.P. is smaller than the Ksp, is the solution saturated, unsaturated, or supersaturated?

A

If I.P. <ksp></ksp>

182
Q

What if the I.P. is equal to the Ksp, is the solution saturated, unsaturated, or supersaturated?

A

If I.P. = Ksp then the solution is saturated

183
Q

What is the common ion effect

A

When a slightly soluble salt is added to a solution which already contains one of its components, the added salt is less soluble than if it were added to a pure solvent

184
Q

What is the Bonsted-Lowry definition of an acid?

A

Bronsted Lowry theory defines an acid as a species that donates protons

185
Q

What is the Bonsted-Lowry definition of a base?

A

Bronsted Lowry theory defines a base as a species that accepts protons

186
Q

What is the Lewis definition of an acid

A

Lewis Acid is a species that accepts an electron pair

187
Q

What is the Lewis definition of a base

A

A Lewis Base is a species that donates an electron pair

188
Q

At 25 degrees C, pH + pOH =

A

pH +pOH = 14

189
Q

What is the water dissociation constant at 25 degrees celcius? Kw=

A

Kw = [H+][OH-] = 1 x 10 -14

190
Q

Is a solution with a pH of 4 acidic or basic?

A

A pH of 4 corresponds to an acidic solution

191
Q

Is a solution with a pOH of 4 acidic or basic?

A

a pOH of 4 (pH = 10) corresponds to a basic solution

192
Q

What is the pH of a solution at 25 degrees celcius with a pOH of 5?

A

pH= 14 - pOH = 9

193
Q

What is the logarithmic formula for calculating pH

A

pH= -log[H+]

194
Q

What is the logarithmic formula for calculating pOH

A

pOH= -log[OH-]

195
Q

What is the pH of a 1 x 10 -4 M HCl solution

A

pH= 4

196
Q

Would the pH of a 1.4 x 10 -4 M HCl solution be greater than 4 or less than 4

A

The pH would be less than 4

197
Q

What is the product of a neutralization reaction?

A

The product of a neutralization reaction is salt

198
Q

Will the titration of a weak acid with a strong base produce a slightly acidic or slightly basic solution?

A

A weak acid and a strong base produces a slightly basic solution

199
Q

Will the titration of a strong acid with a strong base produce a slightly acidic, slightly basic, or neutral solution?

A

A strong acid and base produces a neutral solution

200
Q

Will the titration of a strong acid with a weak base produce a slightly acidic or slightly basic solution?

A

A strong acid and a weak base produces a slightly acidic solution

201
Q

What would Kb equal if Ka = 1 x 10 -6

A

Kb= 1 x 10 to the -8

202
Q

What would Ka equal if Kb= 1x10 - 3

A

Ka = 1 x 10 to the -11

203
Q

T/F: an Acid equivalent is equal to one mole of H+

A

True

204
Q

Does a high Ka correspond to a weak acid or a strong acid?

A

A high Ka corresponds to a strong acid

205
Q

Does a high pKa correspond to a weak acid or a strong acid?

A

A high pKa corresponds to a weak acid

206
Q

What is a polyprotic acid?

A

A polyprotic acid can lose more than one proton e.g. H2SO4 and H3PO4

207
Q

What is an amphoteric species? Would the pH equivalence point for the following titrations be equal to 7, greater than 7 or less than 7?

A

An amphoteric species can act as both an acid and a base

208
Q

Strong acid + strong base yield a pH of:

A

ph of 7

209
Q

Weak acid + strong base yield a pH of:

A

pH greater than 7

210
Q

T/F: A buffer solution consists of a mixture of a strong acid and its salt

A

False, a buffer solution consists of a mixture of a weak acid and its salt or a weak base and its salt

211
Q

What is the Henderson Hasselbach equation for a weak acid buffer solution?

A

pH= pKa + log [conjugate base] / [weak acid]

212
Q

What is the Henderson Hasselbalch equation for a weak base buffer solution?

A

pOH= pKb + log [conjugate acid] / [weak base]

213
Q

Does the gain of electrons result in reduction or oxidation?

A

The gain of electrons results in REDUCTION. OIL RIG

214
Q

Does the lost of electrons result in reduction or oxidation?

A

The loss of electrons results in OXIDATION OIL RIG

215
Q

T/F: An oxidizing agent is oxidized in an electrochemical reaction

A

False, an oxidizing agent is a species that gains electrons and thereby causes another agent to be oxidized

216
Q

What is a reducing agent?

A

A reducing agent is a species that loses electrons (gets oxidized) and thereby causes another agent to be reduced.

217
Q

What is the oxidation number of free elements (i.e. He, H2, N2, etc)?

A

The oxidation number of free elements is zero

218
Q

T/F: Group IA elements usually have a +1 charge in a compound, and Group IIA usually have a +2.

A

True

219
Q

What is the oxidation number of oxygen in most compounds?

A

Oxygen typically has an oxidation number of -2

220
Q

What is the oxidation number of a Group VIIA element in a compound?

A

Group VIIA elements have a -1 oxidation number EXCEPTION: If a Group VIIA element is combined with an element with a higher electronegativity, then the oxidation number is +1 or higher.

221
Q

What are the two types of electrochemical cells

A

The two types of electrochemical cells are: Galvanic (or voltaic) Electrolytic

222
Q

Does oxidation occur at the anode or cathode?

A

Oxidation occurs at the anode. AN OX / RED CAT = ANODE OXIDATION / REDUCTION CATHODE

223
Q

Does reduction occur at the anode or the cathode?

A

Reduction occurs at the Cathode AN OX / RED CAT = ANODE OXIDATION / REDUCTION CATHODE

224
Q

Which type of electrochemical cell generates energy?

A

A galvanic cell supplies energy

225
Q

Does a galvanic cell have a positive or negative ∆G?

A

A galvanic cell has a NEGATIVE ∆G and is therefore spontaneous -∆G = spontaneous

226
Q

What is the function of a salt bridge?

A

A salt bridge permits the balancing of charge between the cells

227
Q

T/F: A cell diagram adheres to the following conventions: anode|anode solution || cathode solution|cathode

A

True

228
Q

Does an electrolytic cell have a positive or negative ∆G?

A

An electrolytic cell has a positive ∆G and is therefore non-spontaneous +∆G = non-spontaneous

229
Q

In which electrochemical cell is the anode positive?

A

An electrolytic cell has a POSITIVE ANODE

230
Q

In which electrochemical cell is the cathode positive?

A

A galvanic cell has a POSITIVE CATHODE

231
Q

What is a faraday (F)?

A

A Faraday (F) is equivalent to the amount of charge contained in one mole of electrons (=96,487 C)

232
Q

T/F: Electrons always flow from the anode to the cathode

A

True

233
Q

Define reduction potential

A

Reduction potential is defined as the tendency of a species to acquire electrons. **wants to be reduced (RIG)

234
Q

What is the formula for EMF of a galvanic cell?

A

EMF = E°red + E°ox **remember: if only given values for E°red…you need to flip to + value for oxidation!

235
Q

T/F: When adding standard potentials, multiply by the number of moles oxidized or reduced first.

A

False. never multiply by the number of moles when adding standard potentials

236
Q

What is the formula for the standard free energy of an electrochemical cell? ∆G° =

A

∆G° = - nFE°cell ∆G° = - (number of moles)(Faraday’s constant)(EMF)

237
Q

What is the relationship between EMF and Keq?

A

nFE°cell = RTlnKeq so…∆G° = RTlnKeq!

238
Q

What is an electrolyte?

A

An electrolyte is a substance that dissociates completely in water to form ions, which can then conduct electricity.

239
Q

List some Strong Acids that you should know:

A
  • HCl
  • H2SO4
  • HBr
  • HI
  • HNO3
  • HClO3 (chloric acid)
  • HClO4(perchloric acid)
240
Q

List some Strong Bases you should know:

A
  • KOH
  • NaOH
  • NH2-
  • CaO
  • Ca(OH)2
  • Na2O
  • H-
241
Q

Recognize a hydronium ion:

A

H3O+ Think of this as simply a hydrated proton. ((for acid and base rxns …a hydronium ion and proton are synonymous))

MCAT (4 decks)

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