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Polyatomic Ions > AP Chemistry Midterm Review > Flashcards

AP Chemistry Midterm Review Flashcards

1
Q

Which of the following best represents the ground state of the electrons in n=2 for the N– ion?

a. ¡ ¡! ¡ !
b. ¡ ¡¡ ¡ ¡
c. ¡! ¡! ¡ ¡
d. ¡! ¡ ¡ ¡
e. ¡! ¡! ¡ ¡

A

e. ¡! ¡! ¡ ¡

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2
Q

Atoms having equal or nearly equal electronegativities are expected to form

a. no bonds
b. nonpolar covalent bonds
c. polar covalent bonds
d. ionic bonds
e. covalent bonds

A

b. nonpolar covalent bonds

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3
Q

Which of the following have 10 electrons in the d orbitals?

a. Cu
b. Mn
c. Fe
d. Zn
e. two of the above

A

e. two of the above

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4
Q

Nitrogen has five valence electrons. Consider the following electron arrangements.

        2s           2p

a) ¡! ¡ ¡ ¡
b) ¡ ¡! ¡ !
c) ¡ ¡¡ ¡ ¡
d) ¡! ¡ ¡
e) ¡! ¡! ¡ ¡

Which of the following represents the ground state for the N- ion?

A

e. option e

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5
Q

Nitrogen has five valence electrons. Consider the following electron arrangements.

        2s           2p

a) ¡! ¡ ¡ ¡
b) ¡ ¡! ¡ !
c) ¡ ¡¡ ¡ ¡
d) ¡! ¡ ¡
e) ¡! ¡! ¡ ¡

Which represents the ground state for N?

A

a. option a

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6
Q

Atomic radium generally increases as we move _________.

a. down a group and from left to right across a period
b. down a group and from right to left across a period
c. up a group and from left to right across a period
d. up a group and from right to left across a period
e. down a group. The period position has no effect.

A

b. down a group and from right to left across a period

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7
Q

Of the following elements, which has the largest FIRST ionization energy?

a. Cl
b. Al
c. Br
d. Na
e. Se

A

a. Cl

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8
Q

The successive ionization energies for a certain element are outlined in the table above. Predict the identity of the element from the given information (Jump from E2 to E3).

a. P
b. Mg
c. Na
d. Al
e. Si

A

b. Mg

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9
Q

Which of the following correctly lists the five atoms in order of increasing size (smallest to largest)?

a. F, O, S, Mg, Ba
b. O, F, S, Ba, Mg
c. F, O, S, Ba, Mg
d. F, S, O, Mg, Ba
e. O, F, S, Mg, Ba

A

a. F, O, S, Mg, Ba

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10
Q

Electrons in the 1s subshell are much closer to the nucleus in Ar than in He due to the larger _____ in Ar.

a. effective nuclear charge
b. paramagnetism
c. Hund’s rule
d. diamagnetism
e. azimuthal quantum number

A

a. effective nuclear charge

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11
Q

What is the maximum number of electrons that can be held in a shell with a principal quantum number of n=3?

a. 8
b. 24
c. 18
d. 2
e. 32

A

c. 18

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12
Q

Which of the following has the smallest radius?

a. Xe
b. Ca +2
c. Kr
d. S -2
e. Br -

A

b. Ca +2

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13
Q

How many grams of H2O will be formed when 32.0 g H2 is mixed with 12.0 g of O2 and allowed to react to form water?

a. 144 g
b. 6.8 g
c. 286 g
d. 3.4 g
e. 13.5 g

A

e. 13.5 g

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14
Q

The first ionization energy of Mg is 735 kJ/mol. The second ionization energy is

a. 735 kJ/mol
b. less than 735 kJ/mol
c. more information is needed to answer this question
d. greater than 735 kJ/mol
e. none of these

A

d. greater than 735 kJ/mol

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15
Q

Choose the compound with the most ionic bond.

a. LiF
b. NaCl
c. KF
d. LiCl
e. KCl

A

c. KF

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16
Q

Order the elements S, Cl, and F in terms of increasing ionization energy.

a. Cl, F, S
b. S, Cl, F
c. S, F, Cl
d. F, S, Cl
e. F, Cl, S

A

b. S, Cl, F

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17
Q

A substance contains 35.0 g nitrogen, 5.05 g hydrogen, and 60.0 g oxygen. How many grams of hydrogen are there in a 153-g sample of this substance?

a. 767 g
b. 15.4 g
c. 30.3 g
d. 5.05 g
e. 7.72 g

A

e. 7.72 g

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18
Q

What is the molar mass of ethanol (C2H5OH)?

a. 46.07 g/mol
b. 34.06 g/mol
c. 45.06 g/mol
d. 30.03 g/mol
e. 105.03 g/mol

A

a. 46.07 g/mol

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19
Q

The limiting reactant in a reaction

a. has the lowest coefficient in a balanced equation
b. has the lowest ratio of moles available/coefficient in the balanced equation
c. is the reactant for which you have the fewest number of moles
d. has the lowest ratio of coefficient in the balanced equation/moles available
e. none of these

A

b. has the lowest ratio of moles available/coefficient in the balanced equation

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20
Q

Which of the following best describes an orbital?

a. a single space within an atom that contains all electrons of that atom
b. the space in an atom where an electron is most likely to be found
c. space where electrons are unlikely to be found in an atom
d. small, walled spheres that contain electrons
e. space which may contain electrons, protons, and/or neutrons

A

b. the space in an atom where an electron is most likely to be found

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21
Q

Vitamin C contains the elements C, H, and O. It is known to contain 40.9% C and 4.58% H by mass. The molar mass of vitamin C has been found to be about 180 g/mol. The molecular formula for vitamin C is:

a. C3H4O3
b. C2H3O2
c. C14H18
d. C6H8O6
e. C4H6O4

A

d. C6H8O6

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22
Q

Which of the following groups of species are considered to be isoelectronic?

a. Cl-, I-, F-
b. Kr, Xe, Rn
c. Cl-, Ar, Na+
d. I-, Xe, Ba +2
e. K+, Ca +2, Fe +2

A

d. I-, Xe, Ba +2

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23
Q

For the elements Cs, F, and Cl, the order of increasing electronegativity is:

a. F, Cl, Cs
b. Cs, Cl, F
c. F, Cs, Cl
d. Cl, Cs, F
e. none of these

A

b. Cs, Cl, F

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24
Q

Based on electronegativity differences, which of the following is most likely to be ionic?

a. Br2
b. NO
c. CaF2
d. BH3
e. CF4

A

c. CaF2

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25
Q

Which of the following electron configurations is correct?

a. Ga: [Kr]4s2 3d10 4p1
b. Ca: [Ar]4s1 3d10
c. Mo: [Kr]5s2 4d5
d. Br: [Kr]4s2 3d10 4p7
e. Bi: [Xe]6s2 4f14 5d10 6p3

A

e. Bi: [Xe]6s2 4f14 5d10 6p3

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26
Q

A 7.11-g sample of potassium chlorate was decomposed according to the following equation: 2KClO3->2KCl + 3O2
How many moles of oxygen are formed?

a. 0.0870
b. 0.0580
c. 0.0387
d. 2.78
e. none of these

A

a. 0.0870

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27
Q

Which of the following concerns second ionization energies is true?

a. That of Al is higher than that of Mg because the electrons are taken from the same energy level, but the Al atom has one more proton.
b. The second ionization energies are equal for Al and Mg
c. That of Al is lower than that of Mg because Mg wants to lose the second electron, thus the energy change is greater.
d. That of Al is lower than that of Mg because Mg wants to lose the second electron, so it is easier to take the second electron away.
e. That of Al is lower that that of Mg because the second electron taken from Al is in a p orbital, thus it is easier to take.

A

a. That of Al is higher than that of Mg because the electrons are taken from the same energy level, but the Al atom has one more proton.

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28
Q

Which of the following bonds is least polar?

a. Br—Br
b. H—C
c. S—Cl
d. C—O
e. They are all nonpolar.

A

a. Br—Br

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29
Q

Which of the following atoms or ions has three unpaired electrons?

a. O
b. Al
c. N
d. Ti +2
e. S -2

A

c. N

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30
Q

The formula for calcium bisulfate is

a. Ca(HSO4)2
b. Ca(SO4)2
c. CaS2
d. Ca2HSO4
e. Ca2S

A

a. Ca(HSO4)2

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31
Q

Which of the following bonds would be the least polar, yet still be considered polar covalent?

a. C-O
b. Si-O
c. N-O
d. Mg-O
e. O-O

A

c. N-O

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32
Q

In Bohr’s atomic theory, when an electron moved from one energy level to another energy level more distant from the nucleus:

a. Energy is absorbed.
b. No change in energy occurs.
c. Energy is emitted.
d. Light is emitted.
e. none of these

A

a. Energy is absorbed.

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33
Q

When 233.1 g of ethylene (C2H4) burns in oxygen to give carbon dioxide and water, how many grams of CO2 are formed?

a. 8.31 g
b. 182.9 g
c. 365.7 g
d. 299.4 g
e. 731.4 g

A

e. 731.4 g

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34
Q

All of the following are in aqueous solution. Which is INCORRECTLY named?

a. H2SO3, sulfurous acid
b. HNO2, nitrous acid
c. HClO3, chloric acid
d. HBr, bromic acid
e. HC2H3O2, acetic acid

A

d. HBr, bromic acid

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35
Q

Adipic acid contains 49.32% C, 43.84% O, and 6.85% H by mass. What is the empirical formula?

a. C3H3O4
b. C3H5O2
c. C3HO3
d. C2HO3
e. C2H5O4

A

b. C3H5O2

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36
Q

The formula for sodium dihydrogen phosphate is

a. Na2H2PO4
b. NaH2PO4
c. Na2HPO4
d. Na(HPO4)2
e. NaHPO4

A

b. NaH2PO4

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37
Q

Which of the following species would be expected to have the lowest ionization energy?

a. Ne
b. Na+
c. F-
d. O -2
e. Mg +2

A

d. O -2

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38
Q

An unknown substance dissolves readily in water but not in benzene (a nonpolar solvent). Molecules of what type are present in the substance?

a. neither polar or nonpolar
b. polar
c. either polar or nonpolar
d. nonpolar
e. none of these

A

b. polar

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39
Q

Which of the following is a strong acid?

a. HF
b. KOH
c. HClO4
d. HClO
e. HBrO

A

c. HClO4

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40
Q

Which of the following is NOT a strong base?

a. Ca(OH)2
b. KOH
c. NH3
d. LiOH
e. Sr(OH)2

A

c. NH3

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41
Q

A 16.4-g sample of HF is dissolved in water to give 2.0 x 10^2 mL of solution. The concentration of the solution is:

a. 0.82 M
b. 0.16 M
c. 0.08 M
d. 4.1 M
e. 8.2 M

A

d. 4.1 M

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42
Q

How many grams of NaCl are contained in 350 mL of a 0.287 M solution of sodium chloride?

a. 16.8 g
b. 5.87 g
c. 11.74 g
d. 100.5 g
e. none of these

A

b. 5.87 g

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43
Q

Which of the following aqueous solutions contains the greatest number of ions?

a. 400.0 mL of 0.10 M NaCl
b. 300.0 mL of 0.10 M CaCl2
c. 200.0 mL of 0.10 M FeCl3
d. 200.0 mL of 0.10 M KBr
e. 800.0 mL of 0.10 M sucrose

A

b. 300.0 mL of 0.10 M CaCl2

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44
Q

What mass of solute is contained in 256 mL of a 0.838 M ammonium chloride solution?

a. 11.5 g
b. 175 g
c. 16.3 g
d. 215 g
e. 3.27 g

A

a. 11.5 g

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45
Q

The following reactions:

Pb+2 + 2I- -> PbI2
2Ce+4 + 2I- -> I2 + 2Ce+3
HOAc + NH3 -> NH4+ + OAc-

are examples of

a. acid-base reactions
b. unbalanced reactions
c. precipitation, acid-base, and redox reactions, respectively
d. redox, acid-base, and precipitation reactions, respectively
e. precipitation, redox, and acid-base reactions, respectively
e.

A

e. precipitation, redox, and acid-base reactions, respectively

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46
Q

You have exposed electrodes of a light bulb in a solution of H2SO4 such that the light bulb is on. You add a dilute solution and the bulb grows dim. Which of the following could be in the solution?

a. Ba(OH)2
b. NaNO3
c. K2SO4
d. Cu(NO3)2
e. none of these

A

a. Ba(OH)2

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47
Q

Aqueous solutions of potassium sulfate and ammonium nitrate are mixed together. Which statement is correct?

a. Both KNO3 and NH4SO4 precipitate from solution.
b. A gas is released.
c. NH4SO4 will precipitate from solution.
d. KNO3 will precipitate from solution.
e. No reaction will occur.

A

e. No reaction will occur.

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48
Q

Which of the following salts is insoluble in water?

a. Na2S
b. K2CO3
c. Pb(NO3)2
d. CaCl2
e. All of these are soluble in water.

A

e. All of these are soluble in water.

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49
Q

The oxidation state of iodine in IO3^- is:

a. 0
b. +3
c. -3
d. +5
e. -5

A

d. +5

50
Q

The oxidation state of chlorine in ClO- is:

a. 0
b. +1
c. -1
d. +3
e. -3

A

b. +1

51
Q

In the reaction 2Ca(s) + O2(g) -> 2CaO(s), which species is oxidized?

a. O2
b. O -2
c. Ca
d. Ca +2
e. none of these

A

c. Ca

52
Q

In the reaction 2Cs(s) + Cl2(g) -> 2CsCl(s), Cl2 is

a. the reducing agent
b. the oxidizing agent
c. oxidized
d. the electron donor
e. two of these

A

b. the oxidizing agent

53
Q

In the reaction C(s) + O2(g) -> CO2(g), carbon is ________.

a. the reducing agent
b. the electron acceptor
c. reduced
d. the oxidizing agent
e. more than one of these

A

a. the reducing agent

54
Q

Which of the following reactions does NOT involve oxidation-reduction?

a. CH4 + 3O2 -> 2H2O + CO2
b. Zn + 2HCl -> ZnCl2 + H2
c. 2Na + 2H2O -> 2NaOH + H2
d. MnO2 + 4HCL -> Cl2 + 2H2O + MnCl2
e. All are oxidation-reduction reactions.

A

e. All are oxidation-reduction reactions.

55
Q

Which of the following statements is (are) true? Oxidation and reduction

a. cannot occur independently of each other
b. accompany all chemical changes
c. describe the loss and gain of electron(s) respectively
d. result in a change in the oxidation states of the species involved
e. A, C, and D

A

e. A, C, and D

56
Q

Consider the following unbalanced oxidation-reduction reaction:

Fe +2 + Br2 -> Fe +3 + Br-

In the balanced equation, the number of electrons transferred is

a. 1
b. 3
c. 2
d. 4
e. none of these

A

c. 2

57
Q

Given the reaction:

2MnO4- + 5H2O2 + 6H+ -> 2Mn+2 + 8H2O + 5O2

determine the number of electrons involved in this reaction.

a. 10
b. 8
c. 6
d. 4
e. 2

A

a. 10

58
Q

Select the spectator ions for the following reaction, Pb(NO3)2 + 2KCl -> PbCl2 + 2KNO3

a. K+ (aq), NO3- (aq)
b. Pb+2 (aq), NO3- (aq)
c. K+ (aq), Cl- (aq)
d. Pb+2 (aq), Cl- (aq), K+ (aq), NO3- (aq)
e. Pb+2 (aq), Cl- (aq)

A

a. K+ (aq), NO3- (aq)

59
Q

Aqueous solutions of barium chloride and silver nitrate are mixed to form solid silver chloride and aqueous barium nitrate.

The balanced molecular equation contains which of the following terms?

a. AgCl (s)
b. 2AgCl (s)
c. 2Ba(NO3)2 (aq)
d. BaNO3 (aq)
e. 3AgCl (aq)

A

b. 2AgCl (s)

60
Q

A 1.59-g sample of a metal chloride, MCl2, is dissolved in water and treated with excess aqueous silver nitrate. The silver chloride that formed weighed 3.60 g. Calculate the molar mass of M.

a. 70.9 g/mol
b. 28 g/mol
c. 55.9 g/mol
d. 63 g/mol
e. 72.4 g/mol

A

c. 55.9 g/mol

61
Q

In the reaction N2(g) + 3H2(g) -> 2NH3(g), N2 is

a. oxidized
b. reduced
c. the electron donor
d. the reducing agent
e. two of these

A

b. reduced

62
Q

When a carbon atom has sp3 hybridization, it has

a. two pi bonds and two sigma bonds
b. one pi bond and three sigma bonds
c. four pi bonds
d. three pi bonds and one sigma bond
e. four sigma bonds

A

e. four sigma bonds

63
Q

Choose the molecule with the strongest bond.

a. HCl
b. All are equal.
c. HI
d. HF
e. HBr

A

d. HF

64
Q

Which of the following molecules contains a central atom with sp2 hybridization?

a. AlH3 + PCl3
b. H3P
c. BeCl2
d. H5N2
e. BF3

A

e. BF3

65
Q

Bond energy is the energy

a. required to form a chemical bond.
b. required to break a chemical bond.
c. absorbed when a chemical bond forms.
d. released when a chemical bond breaks.

A

b. required to break a chemical bond.

66
Q

As the bond order of a bond increases, the bond energy _____ and the bond length _____.

a. decreases, increases
b. increases, decreases
c. decreases, decreases
d. increases, increases
e. More information is needed to answer this question.

A

b. increases, decreases

67
Q

Which of the following exhibits resonance?

a. At least two of the molecules (A-D) exhibit resonance.
b. O3
c. PCl5
d. H2O
e. NH3

A

b. O3

68
Q

Choose the electron dot formula that most accurately describes the bonding in CS2.

a. C=S=S
b. S-C-S
c. S=C=S
d. S-C=_S
e. S-C=S

A

c. S=C=S

69
Q

Which of the following molecules has no dipole movement?

a. none
b. H2O
c. CO2
d. NH3
e. all

A

c. CO2

70
Q 
Given the following bond energies:
C-C  347 kJ/mol
C=C  614 kJ/mol
C-O  358 kJ/mol
C=O  799 kJ/mol
C-H  413 kJ/mol
O-H  463 kJ/mol
O-O  146 kJ/mol

estimate delta H for the reaction H2O2 + CH3OH -> H2CO + 2H2O.

a. -105 kJ
b. -199 kJ
c. -345 kJ
d. +345 kJ
e. +199 kJ

A

c. -345 kJ

71
Q

Which of the following molecules are nonlinear?
NO2 -, C2H2, N3 -, HCN, CO2, H2O2

a. C2H2, HCN
b. NO2 -, H2O2
c. all are linear
d. N3 -, NO2 -
e. CO2, N3 -

A

b. NO2 -, H2O2

72
Q

Calculate the formal charge on the nitrogen atom in the following structure:

O-N-O-H
=
O

a. 0
b. +1
c. +2
d. -1
e. -2

A

b. +1

73
Q

Which of the following has an incomplete octet in its Lewis structure?

a. CO2
b. ICl
c. NO
d. F2
e. SO2

A

c. NO

74
Q

A pi bond is the result of the

a. overlap of two s orbitals
b. sideways overlap of two parallel p orbitals
c. sideways overlap of two s orbitals
d. overlap of two p orbitals along their axes
e. overlap of an s orbital and a p orbital

A

b. sideways overlap of two parallel p orbitals

75
Q

According to VSEPR theory, an AX^3 molecule is

a. trigonal planar
b. octahedral
c. linear
d. tetrahedral

A

a. trigonal planar

76
Q

Which of the following Lewis structures best describes BF3?

A

Draw

77
Q

Consider the reaction

H2(g) + 1/2O2(g) -> H2O(l) delta H° = -286 kJ

Which of the following is true?

a. The reaction is exothermic.
b. The reaction is endothermic.
c. The enthalpy of the products is less than that of the reactants.
d. Heat is absorbed by the system.
e. Both A and C are true.

A

e. Both A and C are true.

78
Q

Which of the following does NOT have a standard enthalpy of formation equal to zero at 25°C and 1.0 atm?

a. F2(g)
b. Al(s)
c. H2O(l)
d. H2(g)
e. They all have a standard enthalpy equal to zero.

A

c. H2O(l)

79
Q

Consider the following processes:

                          delta H (kJ/mol)  3B -> 2C + D      -125 (1/2)A -> B            150 E +A -> D              350

Calculate delta H for: B -> E + 2C

a. -175 kJ/mol
b. 525 kJ/mol
c. 325 kJ/mol
d. -325 kJ/mol
e. none of these

A

a. -175 kJ/mol

80
Q

Find the enthalpy change, delta H, for the following reaction using the information in the table below.
N2+O2->2NO

a. -301 kJ/mol
b. 829 kJ/mol
c. -222 kJ/mol
d. 222 kJ/mol
e. 301 kJ/mol

A

d. 222 kJ/mol

81
Q

Find the enthalpy change, delta H°, for the following reaction using the information in the table below.
N2+3H2->2NH3

a. 151 kJ/mol
b. 109 kJ/mol
c. 982 kJ/mol
d. -109 kJ/mol
e. -151 kJ/mol

A

d. -109 kJ/mol

82
Q

Using the information below, calculate delta H of formation for PbO(s)

PbO(s)+CO(g)->Pb(s) + CO2(g) H°= -131.4 kJ
Hf° for CO2(g) = -393.5 kJ/mol
Hf° for CO(g) = -110.5 kJ/mol

a. +283.0 kJ/mol
b. -151.6 kJ/mol
c. -283.0 kJ/mol
d. -372.6 kJ/mol
e. +252.1 kJ/mol

A

b. -151.6 kJ/mol

83
Q

At 25°C, the following heats of reaction are known:

                                                   H (kJ/mol) 2ClF + O2 -> Cl2O + F2O            167.4 2ClF3 + 2O2 -> Cl2O + 3F2O     341.4 2F2 + O2 -> 2F2O                        -43.4

At the same temperature, calculate delta H for the reaction: ClF + F2 -> ClF3

a. -108.7 kJ/mol
b. +217.5 kJ/mol
c. -130.2 kJ/mol
d. -217.5 kJ/mol
e. none of these

A

a. -108.7 kJ/mol

84
Q

A 45.9 g sample of a metal is heated to 95.2°C and then placed in a calorimeter containing 120.0 g of water (c = 4.18 J/g°C) at 21.6°C. The final temperature of the water is 24.5°C. Which metal was used?

a. Copper (c = 0.20 J/g°C)
b. Aluminium (c = 0.89 J/g°C)
c. Iron (c = 0.45 J/g°C)
d. Lead (c = 0.14 J/g°C)
e. none of these

A

c. Iron (c = 0.45 J/g°C)

85
Q

Which one of the following graphs shows the correct relationship between concentration and time for a reaction that is second order in [A]?

a. ln [A]/ time -slope
b. [A]/ time -slope
c. 1/[A] / time +slope
d. [A]/ time +slope
e. [A]/ time +slope

A

c. 1/[A] / time +slope

86
Q

Why is this reaction considered to be exothermic?

a. Because energy difference B is greater than energy difference C.
b. Because energy difference B is greater than energy difference C plus energy difference A.
c. Because energy difference B is greater than energy difference A.
d. Because energy difference A and energy difference C are about equal.
e. Because energy difference A is greater than energy difference C.

A

c. Because energy difference B is greater than energy difference A.

87
Q

If the reactions were reversible, would the forward or the reverse reaction have a higher activation energy?

a. The reverse activation energy would be greater.
b. The forward and reverse activation energies are equal.
c. The diagram shows no indication of any activation energy.
d. The forward activation energy would be greater.
e. None of these.

A

a. The reverse activation energy would be greater.

88
Q

The energy diagram for the reaction X + Y -> Z is shown below. The addition of a catalyst to this reaction would cause a change in which of the indicated energy differences?

a. II only
b. I only
c. III only
d. I, II, and III
e. I and II only

A

e. I and II only

89
Q

In general, as temperature goes up, reaction rate

a. goes up if the reaction is exothermic
b. stays the same if the reaction is first order
c. stays the same regardless of whether the reaction is exothermic or endothermic
d. goes up if the reaction is endothermic
e. goes up regardless of whether the reaction is exothermic or endothermic

A

e. goes up regardless of whether the reaction is exothermic or endothermic

90
Q

The rate law of a reaction is rate = k[A]^x. The units of k, if the reaction is second order in A, are _______.

a. M^-1s^-1
b. M/s
c. 1/M
d. 1/s
e. s/M^2

A

a. M^-1s^-1

91
Q

The rate law of the stoichiometric equation

A + B -> C

is rate k[A]^2. Which of the following will NOT increase the rate of the reaction?

a. increasing the concentration of reactant B
b. adding a suitable catalyst
c. increasing the temperature of the reaction
d. increasing the concentration of reactant A
e. none of these will increase the reaction rate

A

a. increasing the concentration of reactant B

92
Q

The stoichiometric equation for a reaction is:

2A + 2B -> C

The mechanism for this reaction is:

(1) A + B -> D (slow)
(2) D + B -> E (fast)
(3) A + E -> C (fast)

Of the following rate laws, _______ is the correct rate law for this mechanism.

a. Rate = k3[A][E]
b. Rate = k1[A]^2[B]^2
c. Rate = k1[A][B]
d. Rate = k2k3[A][B][D]
e. Rate = k2[D][B]

A

c. Rate = k1[A][B]

93
Q

The rate constant for a second-order reaction is 0.13 M-1s-1. If the initial concentration of reactant is 0.26 mol/L, it takes _____________s for the concentration to decrease to 0.13 mol/L.

a. 30
b. 1.0
c. 4.4 x 10^-3
d. 0.017
e. 0.50

A

a. 30

94
Q

Which of the following does not play a part in determining the rate of a reaction?

a. temperature
b. the presence of a catalyst
c. the equilibrium constant
d. the concentration of reactants
e. the surface area of solid or liquid reactants

A

c. the equilibrium constant

95
Q

In the reaction 2NO2 -> 2NO + O2 at 300°C., [NO2] drops from 0.0100 to 0.00650 M in 100 s. The rate of disappearance of NO2 for this period is ________ M/s.

a. 0.000035
b. 0.0035
c. 0.0018
d. 0.0070
e. 0.35

A

a. 0.000035

96
Q

The reaction

2NO2 -> 2NO + O2

follows second-order kinetics. At 300°C, [NO2] drops from 0.0100 to 0.00650 M in 100 s. Use of the integrated form of the proper rate equation affords a value of _______ L/mol-1s for the rate constant k.

a. 1.2
b. 0.54
c. 0.81
d. 0.096
e. 0.65

A

b. 0.54

97
Q

Given the data below for the reaction

y^Y + z^Z -> products

the rate constant is _______ L^2/mol^2-s.

a. 2.5 x 10^2
b. 1.6 x 10^-4
c. 4.0 x 10^-3
d. 2.5 x 10^-2
e. 4.0 x 10^-2

A

e. 4.0 x 10^-2

98
Q

The table below contains concentration and rate data for the reaction:

A + 2B -> C

The rate law for this reaction is _________

a. R = k[A]^4
b. R = k[A]^4[B]
c. R = k[A]^3
d. R = k[A]
e. R = k[A]^2[B]

A

d. R = k[A]

99
Q

Use the potential energy diagram shown to answer the following:

Which letter shows the change in energy for the overall reaction?

a. a
b. b
c. c
d. d
e. e

A

d. d

100
Q

The initial concentration of reactant in a first order reaction is 0.1 M. The rate constant for the reaction is 0.5 s-1. What is the concentration (in mol/L) of reactant after 1 seconds?

a. 0.165
b. 0.016
c. 0.061
d. 0.05
e. 0.139

A

c. 0.061

101
Q

A reaction was found to be third order in A. Increasing he concentration of A by a factor of 3 will cause the reaction rate to _________.

a. decrease by a factor of the cube root of 3
b. remain constant
c. increase by a factor of 9
d. triple
e. increase by a factor of 27

A

e. increase by a factor of 27

102
Q

Select the rate law that corresponds to the data shown for the following reaction.

A + B -> C

a. Rate = k[B]
b. Rate = k[A][B]^3
c. Rate = k[B]^3
d. Rate = k[A]^2[B]^2
e. Rate = k[B]^4

A

c. Rate = k[B]^3

103
Q

Reaction rate depends on ____________.

a. collision frequency
b. collision orientation
c. collision energy
d. all of these
e. none of these

A

d. all of these

104
Q

The half-life of a first-order reaction is 13 min. If the initial concentration of the reactant is 0.085 M, it takes _________ min for it to decrease to 0.055 M.

a. 0.048
b. 3.6
c. 11
d. 8.4
e. 8.2

A

e. 8.2

105
Q

Consider the reaction: 4NH3 + 7O2 -> 4NO2 + 6H2O

At a certain instant the initial rate of disappearance of the oxygen gas is X. What is the value of the appearance of water at the same instant?

a. 1.2 X
b. 0.58 X
c. 0.86 X
d. 1.1 X
e. cannot be determined from the data

A

c. 0.86 X

106
Q

For the reaction: 2SO2(g) -> 2SO(g) + O2(g), the disappearance of SO2(g) was measured to monitor the progress of the reaction.

Calculate the average rate of disappearance of SO2 between 10.0 and 30.0 seconds.

a. 0.0132 M/s
b. 0.00877 M/s
c. 0.00775 M/s
d. 0.00386 M/s
e. 0.00517 M/s

A

c. 0.00775 M/s

107
Q

Which of the following result(s) in an increase in the entropy of the system?

I. Increase in space
II. Br2(g) -> Br2(l)
III. NaBr(s) -> Na+(aq) + Br-(aq)
IV. O2(298 K) -> O2(373 K)
V. NH3(1 atm, 298 K) -> NH3 
(3 atm, 298 K)

a. I
b. II, V
c. I, III, IV
d. I, II, III, IV
e. I, II, III, V

A

c. I, III, IV

108
Q

Consider the following processes:
I. condensation of a liquid
II. increasing the volume of 1.0 mol of an ideal gas at constant temperature
III. dissolving sugar in water
IV. heating 1.0 mol of an ideal gas at constant volume

For how many of these is delta S positive?

a. 0
b. 1
c. 2
d. 3
e. 4

A

d. 3

109
Q

For a particular chemical reaction delta H = 4.3 kJ and delta S = -19 J/K. Under what temperature condition is the reaction spontaneous?

a. When T is less than -226 K.
b. When T is less than 226 K.
c. The reaction is spontaneous at all temperatures.
d. The reaction is not spontaneous at any temperatures.
e. When T is greater than 226 K.

A

d. The reaction is not spontaneous at any temperatures.

110
Q

For a certain process at 355 K, delta G = -11.8 kJ and delta H = -9.2 kJ. Therefore, delta S for the process is

a. 0 J/K mol
b. 7.3 J/K mol
c. -7.3 J/K mol
d. -25.9 J/K mol
e. 25.9 J/K mol

A

b. 7.3 J/K mol

111
Q

At constant pressure, the following reaction 2NO2(g) -> N2O4(g) is exothermic. The reaction (as written) is

a. always spontaneous
b. spontaneous at low temperatures, but not high temperatures
c. spontaneous at high temperatures, but not low temperatures
d. never spontaneous
e. cannot tell

A

b. spontaneous at low temperatures, but not high temperatures

112
Q

The following reaction takes place at 120°C: H2O(l) -> H2O(g) delta H = 44.0 kJ/mol
delta S = 0.119 kJ/mol K

Which of the following must be true?

a. The reaction is not spontaneous.
b. The reaction is spontaneous.
c. Delta G = 0
d. Delta G is less than 0
e. Two of these.

A

e. Two of these.

113
Q

For which of the following processes would delta S° be expected to be most positive?

a. O2(g) + 2H2(g) -> 2H2O(g)
b. H2O(l) -> H2O(s)
c. NH3(g) + HCl(g) -> NH4Cl(g)
d. 2NH4NO3(s) -> 2N2(g) + O2(g) + 4H2O(g)
e. N2O4(g) -> 2NO2(g)

A

d. 2NH4NO3(s) -> 2N2(g) + O2(g) + 4H2O(g)

114
Q

In which reaction is delta S° expected to be positive?

a. I2(g) -> I2(s)
b. H2O(l) -> H2O(s)
c. CH3OH(g) + 3/2O2(g) -> CO2(g) + 2H2O(l)
d. 2O2(g) + 2SO(g) -> 2SO3(g)
e. none of these

A

e. none of these

115
Q

Consider the reaction
2N2O5(g) equilibrium 4NO2(g) + O2(g)

at 25°C for which the following data are relevant:

a. -1.35 x 10^5 kJ
b. 98.7 kJ
c. -25.2 kJ
d. 135 kJ
e. 0

A

c. -25.2 kJ

116
Q

The standard free energy of formation of KCl(s) is -408.8 kJ/mol. Delta G° for the reaction 2KCl(s) -> 2K(s) + Cl2(g) is:

a. -408.8 kJ
b. 817.6 kJ
c. 408.8 kJ
d. -817.6 kJ
e. none of these

A

b. 817.6 kJ

117
Q

For the reaction Cl2O(g) + 3/2O2(g) -> 2ClO2(g), delta H° = 126.4 kJ/mol and delta S° = -74.9 J/K mol. At 361°C, what is delta G?

a. 153.4 kJ/mol
b. 47.6 kJ/mol
c. 173.9 kJ/mol
d. 78.9 kJ/mol
e. 155.0 kJ/mol

A

c. 173.9 kJ/mol

118
Q

Predict the sign of delta S° for each of the following processes:

I. 2K(s) + Cl2(g) -> 2KCl(s)
II. CH4(g) -> C(s) + 2H2(g)
III. CaCO3(s) -> CaO(s) + CO2(g)

a. negative, negative, positive
b. negative, negative, negative
c. positive, negative, negative
d. negative, positive, positive
e. positive, positive, positive

A

d. negative, positive, positive

119
Q

Which of the following reactions will have a positive value of delta S°?

I. Pb(s) + Cl2(g) -> PbCl2(s)
II. 2H2S(g) + 3O2(g) -> 2H2O(g) + 2SO2(g)
III. K2SO4(s) -> 2K+(aq) + SO4 -2 (aq)

a. I only
b. II only
c. III only
d. I and II
e. II and III

A

c. III only

120
Q

The exothermic reaction, 2Cu(s) + O2(g) -> 2Cu(s), is spontaneous

a. At high temperatures
b. At low temperatures
c. At all temperatures
d. The reaction is non spontaneous at all temperatures
e. Cannot be determined with the available information

A

b. At low temperatures

Polyatomic Ions (5 decks)

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