General Chemistry Flashcards
(304 cards)
1
Q
What are the bond orders of single, double, and triple bonds?
A
1st order, 2nd order, and 3rd order, respectively.
2
Q
T/F, a triple bond is longer than a single bond?
A
False, a triple bond is shorter than a single bond
3
Q
What is bond energy?
A
Bond energy is the amount of energy required to separate two bonded atoms.
4
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.
5
Q
Draw the lewis structure for HCN
A
H-C≡N:
6
Q
What is the formula for calculating formal charge on an atom in a covalent bond?
A
Formal charge = V — (1/2 #bonding + #nonbonding)
7
Q
What are resonance structures?
A
Two or more non-identical Lewis structures for the same molecule are resonance structures.
8
Q
T/F, a lewis structure with small or no formal charges is preferred over one with large formal charges?
A
True
9
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.
10
Q
Which type of bond forms between atoms with small differences in electronegativity (0.4-1.7)?
A
A polar covalent bond forms between atoms with small differences in electronegativity.
11
Q
Which type of bond forms between atoms with the same electronegativities?
A
A nonpolar covalent bond forms between atoms with the same electronegativities.
12
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.
13
Q
T/F, a dipole moment exists when a molecule has a separation of positive and negative charges?
A
True
14
Q
What are the 3 steps for determining geometric configuration?
A
- Draw the 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.
15
Q
What is the geometric arangements of CO2?
A
Linear
16
Q
What is the geometric arangements of BH3?
A
Trigonal planar
17
Q
What is the geometric arangements of NH3
A
Pyramidal
18
Q
What is the geometric arangements of CH4?
A
Tetrahedral
19
Q
PCl5
A
Trigonal bipyramidal
20
Q
SF6
A
Octahedral
21
Q
Can molecules with polar bonds be nonpolar?
A
Yes, if there is no net dipole moment within the molecule, it will be nonpolar.
22
Q
What is the shape of an s orbital?
A
A s orbital is spherical
23
Q
What is the shape of a p orbital?
A
A p orbital is bi-lobed
24
Q
What are three types of intermolecular forces?
A
Three types of intermolecular forces are: a. dipole-dipole interactions b. hydrogen bonding c. dispersion forces
25
State the intermolecular forces in order of increasing strength?
Dispersion forces < dipole-dipole < hydrogen bonding
26
Which molecules, polar or nonpolar, typically have higher boiling points?
Polar molecules typically have higher boiling points
27
What is molar mass (molar weight)?
Molar mass is the number of grams per mole of a compound or an element
28
How many equivalents of hydrogen ion are in the following: HCl, H₂SO₄, H₂SO₄, H₃PO₄?
HCl = 1 equivalent H₂SO₄ = 2 equivalents H₂SO₄ = 3 equivalents H₃PO₄ = 3 equivalents
29
What is the formula for gram equivalent weight?
Gram Equivalent Weight = Molar Mass / n
30
What is the formula for calculating equivalents?
Equivalents = Weight of Compound / Gram Equivalent Weight
31
What is an empirical formula?
An empirical formula represents the simplest whole number ratio of the elements present in a compound
32
What is the empirical formula for C₆H₁₂O₆?
The empirical formula is CH₂O
33
What is a molecular formula?
A molecular formula represents the actual number of atoms of each element present in a molecule of the compound
34
What is the formula for calculating percent composition?
%Composition = (Mass of X in Compound / MW of Compound) x 100%
35
Classify the following reaction type: A + X →AX
Combination or addition
36
Classify the following reaction type: AX →A + X
Decomposition
37
Classify the following reaction type: AX + B →BX + A
Single displacement
38
Classify the following reaction type: AX + BY →AY + BX
Double displacement
39
Classify the following reaction type: HA(aq) + BOH(aq) →AB(aq) + H₂O
Neutralization
40
Zn(s) + CuSO4(aq) → Cu(s) + ZnSO4(aq) What is the net ionic equation for the above reaction?
Zn(s) + Cu^2+(aq) + SO4^2-(aq) ––\> Cu(s) + Zn^2+(aq) + SO4^2-(aq)
41
Zn(s) + CuSO4(aq) → Cu(s) + ZnSO4(aq) What is the net ionic equation?
Zn(s) + Cu(²+)(aq) ➜ Cu(s) + Zn(²+)(aq)
42
Zn(s) + CuSO4(aq) → Cu(s) + ZnSO4(aq) Which of the above are spectator ions?
SO₄²- is a spectator ion
43
Balance the following equation: NF₃ + H₂O –––\> HF + NO + NO₂
2NF₃ + 3H₂O –––\> 6HF + NO + NO₂
44
What is a limiting reagent?
A limiting reagent is the reagent that is fully consumed in a reaction.
45
Given 1 mol of Ag and 0.4 mol of S, which is the excess reagent and how many moles will be left after the reaction is complete?
2Ag + S ––––\> Ag₂S
46
What is theoretical yield?
Theoretical yield is the amount of product that can be predicted from a balanced equation.
47
What is actual yield?
Actual yield is the amount of product actually isolated from the reaction experimentally.
48
What is percent yield and what is the formula for calculating it?
Percent yield represents the relationship between actual yield and theoretical yield. Percent Yield = (Actual yield / Theoretical Yield) x 100%
49
What is an elementary reaction?
An elementary reaction is a reaction that cannot be decomposed into other reactions.
50
What is an intermediate?
An intermediate is a complex that appears during the course of a reaction but does no appear in the net reaction, or as a final product.
51
What is the rate determining step of a reaction?
The rate determining step is the slowest step of a reaction.
52
What is the general formula for the rate law of the following reaction? aA + bB ––––\> cC + dD
Rate = k [A]^x [B]^y
53
T/F, Rate = -∆ [reactants] / time or Rate = ∆ [products] / time
True
54
What is the reaction order for the following rate law? rate = k [A] [B]²
Reaction order = 3 (x = 1, y = 2, and order = x + y
55
Is the rate of a zero order reaction dependent on the concentration of the reactants?
No, a zero order reaction has a constant rate that is independent of the concentration of reactants.
56
On a potential energy / Reaction coordinate diagram: What is the vertical difference from the product potential energy to the reactant potential energy?
∆H - Enthalpy change of a reaction is the difference between the potential energy of the products and the potential energy of the reactants.
57
On a potential energy / Reaction coordinate diagram: What is the vertical difference from the initial potential energy to the potential energy of the intermediate in the reaction?
Activation energy (Ea) for the forward reaction.
58
On a potential energy / Reaction coordinate diagram: What is the vertical difference between the intermediate potential energy to the product potential energy?
Activation energy (Ea) for the reverse reaction.
59
What is the enthalpy change of a reaction?
Enthalpy change (∆H) of a reaction is the difference between the potential energy of the products and the potential energy of the reactants.
60
How do increasing temperature and reactant concentration affect the rate of reaction?
Increasing temperature and reactant concentration increase the rate of most reactions.
61
Can the meduium in which a reaction takes place affect the reaction rate?
Yes, the medium can affect the reaction rate.
62
How does a catalyst increase reaction rate?
A catalyst increases the reaction rate by decreasing the Ea
63
What is the equalibrium constnat expression for the follwoing reaction? A + 3B –––\> 2C + 2D
Keq = [C]² [D]² / [A] [B]³
64
Do pure solids or liquids appear in an equilibrium constant expression?
No, pure solids or liquids do not appear in an equilibrium constant expression.
65
Does Keq for a reaction remain constant at all temperatures?
No, Keq is characteristic of a given system at a given temperature.
66
If there is much more product than reactant at equilibrium, what can be said of Keq (as compared to 1)
Keq would be greater than 1.
67
If Keq is very small compared to 1, then what can be said about the amount of reactants and products at equilibrium?
If Keq is less than 1, there will be more reactants than products at equilibrium.
68
According to Le Chatelier's Principle, in which direction will equilibrium shift if products are removed?
If products are removed, equilibrium will shift to favor the forward reaction.
69
How will increasing pressure affect the following reaction? N₂(g) + 3H₂(g) ←→2NH₃
Increasing the pressure will favor the forward reaction.
70
T/F, increasing the pressure of a system will shift equilibrium so as to increase the number of moles produced?
False, increasing pressure will shift equilibrium so as to produce fewer moles of gas.
71
How will decreasing temperature affect the following reaction? A ←→ B + heat
Decreasing temperature will favor the forward reaction.
72
How would increasing temperature affect the following reaction? A ←→ B + heat
Increasing temperature will favor the reverse reaction.
73
What is an isolated system?
An isolated system cannot exchange energy or matter with its surroundings.
74
What is a closed system?
A closed system can exchange energy but cannot exchange matter with its surroundings.
75
What is an open system?
An open system can exchange both energy and matter with its surroundings.
76
What is an isothermal process?
An isothermal process is a process that occurs at a constant temperature.
77
What is an isobaric process?
An isobaric process is a process that takes place at a constant pressure.
78
What is an adiabatic process?
An adiabatic process is a process in which no heat exchange occurs between the system and the surroundings.
79
T/F, heat absorbed by a system is considered positive and heat lost by a system is considered negative?
True.
80
What is an endothermic process?
An endothermic process is a process that absorbs heat from the surroundings.
81
What is an exothermic process?
An exothermic process is a process that releases heat to the surroundings.
82
What is the formula for calculating ∆Hrxn?
q = (mass)(heat capacity)(∆ in Temperature) = mc∆T
83
Does a positive ∆H correspond to an endothermic or exothermic process?
A positive ∆H corresponds to an endothermic process.
84
Does a negative ∆H correspond to an endothermic or exothermic process?
A negative ∆H corresponds to an exothermic process.
85
What is standard heat of formation (∆Hºf)?
∆Hºf is the enthalpy change that occurs when one mole of a compound is formed from its elements in their standard states.
86
What is the ∆Hºf of an element in its standard state?
∆Hºf for an element in its standard state = 0
87
T/F, Hess's Law states that enthalpies of reactions are additive?
True.
88
If the ∆H of a forward reaction is -220 kj/mol, what is the ∆H of the reverse reaction?
The ∆H of the reverse reaction is +220 kJ/mol
89
What is bond dissociation energy?
Bond dissociation energy is the amount of energy required to break a particular bond in one mole of gaseous molecules.
90
What is entropy?
Entropy is the measure of disorder or randomness of a system.
91
When does a system reach maximum entropy?
Maximum entropy occurs when a system is at equilibrium.
92
What is the Gibb's Free Energy equation? ∆G =
∆G = ∆H – T∆S
93
How does the value of ∆G correlate with the spontaneity of a reaction?
∆G is negative for a spontaneous reaction. ∆G is positive for a non-spontaneous reaction.
94
What is the value of ∆G for a system at equilibrium?
∆G at equilibrium = 0
95
T/F, a reaction with (+) ∆H and a (–) ∆S is always spontaneous.
False, a reaction with a (+) ∆H and a (–) ∆S is always non-spontaneous.
96
Under what conditions will a reaction with a (+) ∆H and a (+) ∆S be spontaneous?
At high temperature, a reaction with a (+) ∆H and a (+) ∆S will be spontaneous.
97
Under what conditions will a reaction with a (–) ∆H and a (–) ∆S be spontaneous?
A low temperature, a reaction with a (–) ∆H and a (–) ∆S will be spontaneous.
98
What is standard free energy, ∆Gº?
∆Gº is the ∆G of a process occurring at 25ºC, 1 atm of pressure, and when the concentrations of all reactants and products are 1M.
99
What is standard free energy of formation, ∆Gºf?
∆Gºf is the free energy change that occurs when 1 mole of a compound in its standard state is formed from its elements in their standard states under standard conditions.
100
What is the formula relating ∆Gº to Keq? ∆Gº=
∆Gº = –RT lnKeq
101
T/F, once a reaction comences: ∆G = ∆Gº + RTlnQ
True.
102
What are the three phases of matter?
The three phases of matter are: solid, liquid, and gas.
103
What is standard pressure in atm, mm Hg, and torr?
Standard pressure = 1 atm = 760 mm Hg = 760 torr.
104
T/F, an ideal gas represents a hypothetical gas whose particles take up no volume and eperience no intermolecular forces.
True.
105
What is standard temperature in Kelin? Celcius?
Standard temperature = 273.15 k = 0ºC
106
What is Boyle's Law?
Boyle's Law states that under isothermal conditions, pressure is inversely proportional to volume. P₁V₁ = P₂V₂
107
What is Charles Law?
Charles Law states that under constant pressure, volume is directly proportional to absolute temperature. V₁/T₁ = V₂/T₂
108
What is the ideal gas law?
(pressure)(volume) = (moles)(gas constant)(temperature) PV = nRT
109
T/F, Avogadro's Principle states that at constant temperature and pressure, volume is directly proportional to the number of moles of gas.
True.
110
What is the volume of 1 mole of gas at STP?
1 mole of gas occupies 22.4 liters at STP.
111
What are the typical units of density (for a gas)?
The density units are g/L.
112
T/F, for a specific sample of gas, P₁V₁ / T₁ = P₂V₂ / T₂
True.
113
What is the formula for calculating the density of a gas? d =
d = m/v = P(MM) / RT
114
Under what conditions is the ideal gas law most correct?
Gases behave in a near-ideal fashion at low pressures and high temperatures.
115
How do actual volume and predicted volume of a gas compare at moderatly high pressures? Extrememly high pressures?
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.
116
How do actual volume and ideal volume of a gas compare at very low temperatures?
At very low temperatures, actual volume is less than would be predicted.
117
What is Dalton's Law of partial pressures?
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.
118
What is the formula for calculating partial pressure? PA =
PA = (PT)(XA) ; XA = mole of A / total mol
119
Given a mixture of 2 gases (O₂ and N₂) at STP and occupying 22.4L. If there are 0.75 moles of N₂, how many moles of O₂ are there?
0.25 moles of O₂. (1 mole occupies 22.4L at STP)
120
T/F, a gas molecule's kinetic energy is inversely proportional to the absolute temperature of the gas?
False, kinetic energy is directly proportional to absolute temperature.
121
T/F, the rates at which two gases diffuse are inversely proportional to the square root of their molar masses?
True.
122
What is effusion?
Effusion is the flow of gas particles under pressure from one container to another through a small opening.
123
T/F, the rates of efusion for two molecules are directly proportional to the square root of their molar masses?
False, the rates of effusion are inversely proportional, just as in diffusion.
124
T/F, solid and liquids are often referred to as the condensed phases?
True.
125
What does it mean when two liquids are immiscible?
Immiscible liquids repel each other and do not mix to form a solution.
126
What is an emulsion?
An emulsion is a mixture of immiscible liquids which are broken up into extremely small particles.
127
What is condesation?
Condensation occurs when gas changes to liquid.
128
What is Evaporation?
Evaporation occurs when liquid changes to gas.
129
What is fusion?
Fusion occurs when a solid changes to a liquid.
130
What is solidification (crystallization)?
Solidification of crystallization occurs when a liquid changes to a solid.
131
What is sublimation?
Sublimation occurs when a solid changes directly to a gas.
132
What is deposition?
Deposition occurs when a gas changes directly to a solid.
133
On a pressure / temperature graph, what is the far left/upper area represent?
The far left/upper region represents solid phase.
134
On a pressure / temperature graph, what is the middle/upper region represent?
The middle/upper region represents liquid phase.
135
On a pressure / temperature graph, what is the far right/lower region represent?
The far right/lower region represents the gas phase.
136
On a pressure / temperature graph, what is the point inbetween the solid phase, liquid phase and gas phase region represent?
The point where all phases meet is called the triple point. All three phases exist simultaneously at this point.
137
On a pressure / temperature graph, what is the transition from the far left/upper to the middle/upper region represent?
Fusion, or melting.
138
On a pressure / temperature graph, what is the transition from the far left/upper to the far right/lower region represent?
Sublimation
139
On a pressure / temperature graph, what is the transition from the middle/upper to the far left/upper region represent?
Freezing, crystallization, or solidification.
140
On a pressure / temperature graph, what is the transition from the middle/upper to the far right/lower region represent?
Evaporation, boiling, or vaporization.
141
On a pressure / temperature graph, what is the transition from the far right/lower to the far left/upper region represent?
Deposition.
142
On a pressure / temperature graph, what is the transition from the far right/lower to the middle/upper region represent?
Condensation.
143
What is a colligative property?
A colligative property is a property derived solely from the number of particles present, not the nature of those particles.
144
Name four colligative properties?
Freezing-point depression, boiling-point elevation, osmotic pressure, and vapor pressure lowering.
145
What is the formula for freezing-point depression? ∆Tf =
∆Tf = Kf (molality of solution) = (Kf)(m)
146
What is the formula for boiling-point elevation? ∆Tb =
∆Tb = Kb (molality of solution) = (Kb)(m)
147
Is osmotic pressure proportional to molarity?
Yes, osmotic pressure is proportional to molarity.
148
What is the formula for osmotic pressure? Π =
Π = (Molarity)(Gas constant)(Temperature) = MRT
149
What is the formula for the vapor pressure of A in a solution of A and B? PA =
PA = (mole fraction of A)(PºA) = (XA)(PºA)
150
What is an aqueous solution?
An aqueous solution is one in which water (H2O) is the solvent.
151
What is solubility?
Solubility is the measure of the amount of substance that can be dissolved in a particular solvent at a particular temperature.
152
What is a saturated solution?
A saturated solution contains the maximum amount of solute that can be dissolved in a particular solvent at a particular temperature.
153
Name this ion? Cu+
Copper (I) or Cuprous
154
Name this ion? Cu²+
Copper (II) or Cupric
155
Name this ion? H-
Hydride
156
Name this ion? ClO-
Hypochlorite
157
Name this ion? ClO₂-
Chlorite
158
Name this ion? ClO₃-
Chlorate
159
Name this ion? ClO₄-
Perchlorate
160
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?
True.
161
What is an electrolyte?
An electrolyte is a solute whose solution is conductive.
162
What is the formula for percent composition by mass?
% = (mass of solute) / (mass of solution) x 100
163
What is the defintion of mole fraction (X)?
X = (moles of compound) / (total number of moles)
164
What is the definition of molarity (M)?
M = (moles of solute) / (liters of solution)
165
What is the definition of molality (m)?
m = (moles of solute) / (Kg of solvent)
166
What is the definition of normality (N)?
N = (GEW of solute) / (liters of solution)
167
T/F, a solution which is diluted is related to its initial concentration as follows: MiVi = MfVf
True.
168
Fe(OH)₃ (s) ←→Fe³+ (aq) + 3OH- (aq) What is the ion product (I.P.) for the above reaction?
I.P. = [Fe³+][OH-]³
169
Fe(OH)₃ (s) ←→Fe³+ (aq) + 3OH- (aq) What is the solubility product constant (Ksp) for the above reaction?
Ksp = [Fe³+]sat[OH-]³sat
170
Fe(OH)₃ (s) ←→Fe³+ (aq) + 3OH- (aq) What is the difference between I.P. and Ksp?
I.P. is defined with respect to initial concentrations. Ksp is defined with respect to the concentrations of a saturated solution at equilibrium.
171
If the ion product (I.P.) is larger than the solubility product constant (Ksp), is the solution saturated, unsaturated, or supersatureated?
If I.P. \> Ksp, then the solution is supersaturated.
172
If the I.P. is smaller than the Ksp, is the solution saturated, unsaturated, or supersaturated?
If I.P. < Ksp, then the solution is unsaturated.
173
If the I.P. is equal to the Ksp, is the solution saturated, unsaturated, or supersaturated?
If I.P. = Ksp, then the solution is saturated.
174
What is the comon ion effect?
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.
175
What is the Bronsted-Lowry definition of an acid?
The bronsted-Lowery theory defines an acid as a species that donates protons.
176
What is the Bronsted-Lowry definition of a base?
The Bronsted-Lowry theory defines a base as a species that accepts protons.
177
HNO₂ (aq) + H₂O ←→ NO₂- (aq) + H₃O+ Which of the above molecule(s) is/are the conjugate acid?
HNO₂ is the conjugate acid and NO₂- is its conjugate base.
178
HNO₂ (aq) + H₂O ←→ NO₂- (aq) + H₃O+ Which of the above molecule(s) is/are the conjugate base?
H₃O+ is the conjugate acid of its conjugate base H₂O.
179
What is the Lewis definition of an acid?
A lewis acid is a species that accepts an electron pair.
180
What is the Lewis definition of a base?
A lewis base is a species that donates an electron pair.
181
T/F, all bronsted-lowry acids are lewis acids?
True.
182
Name this acid: HF
Hydrofluoric acid.
183
Name this acid: HClO₄
Perchloric acid.
184
Name this acid: HNO₂
Nitrous acid.
185
Name this acid: HNO₃
Nitric acid.
186
At 25ºC, pH + pOH =
pH + pOH = 14
187
What is the water dissociation constant at 25ºC? Kw =
Kw = [H+] [OH-] = 1 x 10^-14
188
Is a solution with a pH of 4 acidic or basic?
A pH of 4 corresponds to an acidic solution.
189
Is a solution with a pOH of 4 acidic or basic?
A pOH of 4 (pH = 10) corresponds to a basic solution.
190
What is the pH of a solution at 25ºC with a pOH of 5?
pH = 14 – pOH = 9
191
What is the logarithmic formula for calculating pH?
pH = –log [H+]
192
What is the logarithmic formula for calculating pOH?
pOH = –log [OH-]
193
What is the pH of a 1 x 10^-4 M HCl solution?
pH = 4
194
Would the pH of a 1.4 x 10^-4 M HCL solution be greater than 4 or less than 4?
The pH would be less than 4.
195
HCO₃- (aq) ←→ H+ (aq) + CO₃-² What is the Ka for HCO3-?
Ka = [H+][CO₃²-] / [HCO₃-]
196
HCO₃- (aq) ←→ H+ (aq) + CO₃-² What is the Kb for CO₃²- ?
Kb = [HCO₃-] [OH-] / [CO₃²-]
197
For a conjugate acid-base pair at 25ºC, Ka x Kb =
Ka x Kb = 1 x 10-¹⁴
198
What is the conjugate acid of CO₃²- ?
The conjugate acid of CO₃²- is HCO₃-
199
What would Kb equal if Ka = 1x10-6?
Kb = 1x10-8
200
What would Ka equal if Kb = 1x10-3?
Ka = 1x10-11
201
T/F, an acid equivalent is equal to one mole of H+?
True
202
Does a high Ka correspond to a weak acid or a strong acid?
A high Ka corresponds to a strong acid.
203
Does a high Pka correspond to a weak acid or a strong acid?
A high Pka corresponds to a weak acid.
204
What is a polyprotic acid?
A polyprotic acid can lose more than one proton, e.g., H2SO4 or H3PO4
205
What is an amphoteric species?
An amphoteric species can act as both an acid and a base
206
Would the pH of the equivalence point for the following titrations be equal to 7, greater than 7, or less than 7?
Strong acid + strong base yield a pH of:
Strong acid + strong base = pH of 7
207
Would the pH of the equivalence point for the following titrations be equal to 7, greater than 7, or less than 7?
Weak acid + strong base yield a pH of:
Weak acid + strong base = pH greater than 7
208
1. b
2. c
3. a
4. d
209
210
T/F, a buffer solution consists of a mixture of a strong acid and its salt?
False, a buffer solution consists of a mixture of a weak acid and its salt or a weak base ant its salt.
211
What is the Henderson-Hasselbalch equation for a weak acid buffer solution?
pH = pKa + log [conj base] / [weak acid]
212
What is the Henderson-Hasselbalch equation for a weak base buffer solution?
pOH = pKb + log [conjugate acid] / [weak base]
213
Does the gain of electrons result in reduction or oxidation?
The gain of electrons results in reduction. OIL RIG = Oxidation Is Loss, Reduction Is Gain
214
Does the loss of electrons result in the reduction or oxidation?
The loss of electrons results in oxidation.
215
T/F, an oxidizing agent is oxidized in an electrochemical reaction?
False, an oxidizing agent is a species that gains electrons and thereby causes another agent to be oxidized.
216
What is a reducing agent?
A reducing agent is a species that loses electrons an thereby causes another agent to be reduced.
217
What is the oxidation number of free elements (i.e., He, H₂, N₂, etc.)?
The oxidation number of free elements is zero.
218
T/F, Group IA elements usually have a +1 charge in a compound, and Group IIA usually have a +2?
True.
219
What is the oxidation number of oxygen in most compounds?
Oxygen typically has an oxidation number of -2.
220
What is the oxidation number of a Group VIIA element in a compound?
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
What are the two types of electrochemical cells?
The two types of electrochemical cells are: galvanic (or voltaic) and electrolytic.
222
Does oxidation occur at the anode or cathode?
Oxidation occurs at the anode. An Ox / Red Cat = Anode Oxidation / Reduction Cathode
223
Does reduction occur at the anode or cathode?
Reduction occurs at the cathode.
224
Which type of electrochemical cell generates energy?
A galvanic cell supplies energy.
225
Does a galvanic cell have a positive or negative ∆G?
A galvanic cell has a negative ∆G and is therefore spontaneous.
226
What is the function of a salt bridge?
A salt bridge permits the balancing of change between the cells.
227
T/F, a cell diagram adheres to the following conventions: anode | anode solution || cathode solution | cathode
True.
228
Does an electrolytic cell have a positive or negative ∆G?
An electrolytic cell has a positive ∆G and is therefore non-spontaneous.
229
In which electrochemical cell is the anode positive?
An electrolytic cell has a positive anode.
230
In which electrochemical cell is the cathode positive?
A galvanic cell has a positive cathode.
231
What is a farady (F)?
A Faraday (F) is equivalent to the amount of charge contained in one mole of electrons = 96,487 C.
232
T/F, electrons always flow from the anode to the cathode?
True.
233
Define reduction potential.
Reduction potential is defined as the tendency of a species to acquire electrons.
234
Ag+ + e- –––\> Ag (s) Eº = +0.80V Tl+ + e- –––\> Tl (s) Eº = -0.34V Which of the above species will be reduced most easily?
Ag+ will be reduced most easily because it has a higher reduction potential.
235
Ag+ + e- –––\> Ag (s) Eº = +0.80V Tl+ + e- –––\> Tl (s) Eº = -0.34V Which of the above species will be oxidized most easily?
Tl will be oxidized most easily.
236
Ag+ + e- –––\> Ag (s) Eº = +0.80V Tl+ + e- –––\> Tl (s) Eº = -0.34V What is the EMF for a Tl and Ag galvanic cell?
EMF = Eºred + Eºox = 0.8 + 0.34 = 1.14V
237
T/F, when adding standard potentials, multiply by the number of moles oxidized or reduced first?
False, never multiply by the number of moles when adding standard potential.
238
What is the formula for the standard free energy of an electrochemical cell? ∆Gº =
∆Gº = –(number of moles)(Faraday's constant)(EMF) = –nFEºcell
239
What is the relationship between EMF and Keq?
nFEºcell = RT lnKeq
240
How many protons, neutrons, and electrons are in: ²⁴₁₂Mg ?
12 Protons 12 Neutrons 12 Electrons
241
How many protons, neutrons and electrons in: ⁶³₂₉Cu ²+ ?
29 Protons 34 Neutrons 27 Electrons
242
How many protons, neutrons and electrons are in: ³⁵₁₇Cl- ?
17 Protons 18 Neutrons 18 Electrons
243
What are valence electrons?
The electrons farthest from the nucleus, as well as any electrons available for bonding, are the valence electrons.
244
T/F, one amu is equal to 1/12 the mass of a carbon-12 atom?
True.
245
How many particles are in a mole (mol)?
1 mol = 6.022 x 10²³
246
What is atomic weight?
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.
247
What is an isotope?
An isotope is a different form of the same element due to a different number of neutrons.
248
How many more protons are in a carbon-14 atom than in a carbon-12 atom?
None. Carbon-12 and Carbon-14 are isotopes. They thus have the same number of protons.
249
What is an atomic emission spectrum?
An atomic emission spectrum is the unique spectrum of light emitted when an atom's electrons fall to their ground states.
250
What is an atomic absorption spectrum?
A atomic absorption spectrum is the unique spectrum of light absorbed when an atom's electrons are excited to higher energy levels.
251
Define the Heisenberg uncertainty principle.
The Heisenberg uncertainty principle states that it is impossible to know both the momentum and position of an electron at the same time.
252
Define the Paui exclusion principle.
The Pauli exclusion principle states that no two electrons in an atom can have the same four quantum numbers.
253
What does the principal (1st) quantum number (n) represent?
The principal (1st) quantum number (n) is an integer which represents the shell (energy level) of an electron.
254
What is the maximum number of electrons allowed in the second shell (n = 2)
The maximum number of electrons in the second shell is eight. (The maximum number of electrons in any shell equals 2n².)
255
What does the azimuthal (2nd) quantum number (l) represent?
The azimuthal (2nd) quantum number (l) represents the subshell.
256
What are the first four subshells (corresponding to l = 0, 1, 2 and 3)?
The first four subshells are: s, p, d and f
257
What is the formula for the maximum number of electrons allowed in a subshell?
Maximum number of electrons in a subshell = (4l + 2).
258
What does the magnetic (3rd) quantum number (m"l") represent?
The third quantum number (m"l") represents an orbital within a subshell. The possible values range from "-l" to "l".
259
How many orbitals can each subshell acommodate?
The number of orbitals in each subshell are all integers from "l" to "-l". Therefore: s 0 = 1 p –1, 0, 1 = 3 d –2, –1, 0, 1, 2 = 5 f –3, –2, –1, 0, 1, 2, 3 = 7
260
How many fourth quantum numbers (ms) are possible for an electron? what are they?
The two possible values for ms are +1/2 and -1/2.
261
What is Hund's Rule?
Hund's Rule states that electrons will fill to create the maximum number of half-filled orbitals.
262
Which subshell will fill first? 5s or 3d?
3d will fill before 5s.
263
Which subshell will fill first? 6s or 4f?
6s will fill before 4f.
264
Which subshell will fill first? 4p or 3d?
3d will fill before 4p.
265
What is another way to determine which subshell will fill first without drawing the fill diagram?
Compare (n+ "l") values. The lower the sum has lower energy. If the sums are equal, the subshell with the lower n value will fill first.
266
What is paramagnetic material?
A paramagnetic material has unpaired electrons.
267
What is a diamagnetic material?
A diamagnetic material has no unpaired electrons.
268
Does a "period" run horizontally or vertically?
A period runs horizontally.
269
Does a "group" run horizontally or vertically?
A group runs vertically.
270
T/F, groups have the same valence configuration and have similar chemical properties?
True.
271
Which group (A or B) contains the representative elements?
Group A elements are the representative elements.
272
What is the valence configuration for an element in Group VA?
s²p³
273
What is the valence configuration for an element in Group IIIA?
s²p¹
274
What is the valence configuration for an element in group VIIIA?
s²p⁶
275
What is the valence configuration for an element in group VB?
s²d³
276
What is the valence configuration for an element in group VIB?
s¹d⁵
277
Which group of elements (A or B) contains the transition elements?
Group B elements are the transition elements.
278
What happens to the nmber of electrons when one moves from left to right across a row?
Electrons are sequentially added as you move across a row.
279
Are electrons more tightly held or less tightly held as one moves down a column?
Electrons are less tightly held as you move down a column.
280
What is the atomic radii trend within the periodic table?
Atomic radii decrease as you move from left to right across a period and up a group.
281
What is ionization energy (I.E.)?
Ionization energy is the energy required to completely remove an electron from an atom.
282
What is the ionization energy trend within the periodic table?
I.E. increases as you move from left to right across a period and up a group.
283
Compare the value of the first ionization and second ionization energy of an atom.
The second ionization energy is always higher than the first ionization energy of an atom.
284
What is electron affinity?
Electron affinity is the energy released when an atom accepts an electron.
285
What is the elctron affinity trend within the periodic table?
Electron affinity increases as you move from left to right acros a period and up a group.
286
T/F, group VIIIA elements have high electron affinities.
False, Group VIIIA elements have a stable octet and have an electron affinity approaching zero.
287
What is electronegativity?
Electronegativity is a measure of the attraction of an atom has for electrons in a chemical bond.
288
What is the electronegative trend within the periodic table?
Electronegativity increases as you move from left to right across a period and up a group.
289
T/F, metals are found on the left side of the periodic table and are good conductors of electricity and heat?
True.
290
T/F, Nonmetals are found in the middle of the periodic table and are malleable, ductil, and shiny?
False, nonmetals are generally brittle and lusterless, and are located on the upper right side of the periodic table.
291
T/F, metalloids are found between the metals and nonmetals and have varying properties.
True.
292
Which group of elements contains the alkali metals?
Group IA elements are known as the alkali metals.
293
which group of elements contains the halogens?
The halogens are in group VIIA.
294
Which group of elements contains the alkaline earths?
The alkaline earths are in group IIA.
295
Which group of elements contains the noble gases?
The noble gases are in group VIIIA.
296
Which groups of elements contain the transition metals?
The transition metals are in groups IB to VIIIB.
297
What is an ionic bond?
An ionic bond is formed from the transfer of electrons between two atoms.
298
What is a covalent bond?
A covalent bond is formed from sharing of electrons between atoms.
299
What is a polar covalent bond?
A polar covalent bond is one that has properties of both ionic and covalent bonds. Electrons are shared, but not equally.
300
What is a cation?
A cation is a positively-charged ion.
301
What is an anion?
An anion is a negatively-charged ion.
302
Which type of bond forms between two atoms with substantial differences in electronegativities (\>1.7)?
Ionic bonds form between two atoms with substantial differences in electronegativities.
303
T/F, all atoms bond according to the "octet rule"?
False, some atoms such as hydrogen can have only two valence electrons while other can have more than eight.
304
What are some characteristics of ionic compounds?
Ionic compounds form crystal lattices, conduct electricity in solution, and have high melting and boiling points.
