CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 1
ACS Final Review
**Questions are taken from actual past ACS USNCO exams. It is an overview of the topics
that will be covered on the exam based on CHM 1A and CHM 1B materials covered.
Please continue to study and review the materials on your own as well.
In the diagram above the paired open spheres represent H2 molecules and the paired solid spheres represent N2
molecules. When the molecules in the box react to form the maximum possible amount of ammonia (NH3)
molecules, what is the limiting reactant and how many molecules of NH 3 can be formed?
(A)
N2 is limiting. 5 molecules of NH3 can be formed.
(B)
N2 is limiting. 10 molecules of NH3 can be formed.
(C)
H2 is limiting. 8 molecules of NH3 can be formed.
(D)
H2 is limiting.12 molecules of NH3 can be formed.
3.
Vanillin, C8H8O3 (M = 152 g/mol), is the molecule responsible for the vanilla flavor in food. How many
oxygen atoms are present in a 45.0 mg sample of vanillin?
(A)
4.
L?
(A)
5.
1.78 × 1020
(B) 5.35 × 1020
(C) 1.78 × 1023
(D) 5.35 × 1023
What is the molarity of sodium ions in a solution prepared by diluting 250. mL of 0.550 M Na 2SO4 to 1.25
0.110 M
(B) 0.138 M
(C) 0.220 M
(D) 0.275 M
Which of the following is a weak electrolyte in aqueous solution?
(A) HF
(B) NaF
(C) HCl
(D) KCl
6.
The kinetic theory of gases assumes all of the following
EXCEPT:
(A)
Gases are composed of particles in random, ceaseless motion.
(B)
The sizes of gas particles are negligible compared to the size of the container.
(C)
Gas particles do not attract or repel each other.
(D)
(E)
When gas particles collide, kinetic energy is lost.
CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 2
7. A sample of He gas in a flexible container at room temperature exhibits a certain pressure. What will be the new
pressure when the absolute temperature and volume of the container are both halved? The pressure of the He will be
(A) the same.
(B) doubled.
(C) halved.
(D) quadrupled.
8.
Given chemical equations for these reactions
S(s) + O2(g)  SO2(g)
∆H˚ –296.8 kJ•mol–1
H2(g) + ½ O2(g)  H2O(l) ∆H˚ –285.8 kJ•mol–1
H2(g) + S(s)  H2S(g)
∆H˚ –20.6 kJ•mol–1
What is the value of ∆H for the reaction below?
2 H2S(g) + 3 O2(g)
2 H2O(l) + 2 SO2(g)
(A) –603.2 kJ•mol–1
(B) –562.0 kJ•mol–1
(C) –1206.4 kJ•mol–1
(D) –1124.0 kJ•mol–1
9.
Calculate the energy released by the reaction
4 Fe(s) + 3 O2(g)  2 Fe2O3(s) when a 55.8 g sample of iron reacts completely with 1.00 mole of oxygen. The
enthalpy of formation (∆Hf˚) of Fe2O3(s) is –826 kJ•mol–1.
(A) 206 kJ
(B) 413 kJ
(C) 826 kJ
(D) 1650 kJ
10.
What will be the result when 15.0 mL of 0.040 M lead(II) nitrate is mixed with 15.0 mL of 0.040 M
sodium chloride?
Pb2+(aq) + 2 Cl– (aq) [Ksp = 1.7 × 10–5]
PbCl2(s)
(A) A clear solution with no precipitate will result.
(B) Solid PbCl2 will precipitate and excess Pb2+ ions will remain in solution.
(C) Solid PbCl2 will precipitate and excess Cl– ions will remain in solution.
(D) Solid PbCl2 will precipitate and no excess ions will remain in solution.
11.
What is the oxidation number of As in the compound K(NH 4)2AsO4•6H2O?
(A) –3
(B) +1
(C) +3
(D) +5
12. When the equation
__ MnO4– + __ SO32– + __ H+  __ Mn2+ + __ SO42–+ __ H2O
is balanced correctly with the smallest whole number coefficients, what is the coefficient for H 2O?
(A) 3
(B) 5
(C) 8
(D) 10
13.
For which of the following transitions would a hydrogen atom absorb a photon with longest wavelength?
(A) n = 1 to n = 2
(B) n = 3 to n = 2
(C) n = 5 to n = 6
(D) n = 7 to n = 6
CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 3
14.
Which set of quantum numbers is not possible?
a.
n = 2, l = 1, ml = +1, ms = –½
b.
n = 3, l = 2, ml = +1, ms = +½
c.
n = 4, l = 4, ml = –1, ms = +½ (D) n =5, l = 2, ml = 2, ms = –½
15.
What property of the oxygen atom is represented by the equation O(g) + e –
a.
electronegativity (B) first electron affinity
(C) first ionization energy
O–(g)?
(D) lattice energy
16.
Which of the following isoelectronic species has the largest radius?
a.
K+
(B) Ca2+
(C) P3– (D) S2–
17.
Which group best illustrates the transition from nonmetallic to metallic behavior with increasing atomic
number?
(A) Be, Mg, Ca, Sr
(B) N, P, As, Sb
(C) F, Cl, Br, I
18.
(D) Fe, Ru, Os, Hs
Which atom is least likely to violate the octet rule in its compounds?
(A) B
(B) Cl
(C) F
(D) H
19.
In the Lewis structure for formic acid, HCOOH, how many bonding pairs and lone pairs of electrons are
present?
(A) 4 bonding, 2 lone
(B) 4 bonding, 5 lone
(D) 5 bonding, 4 lone
(C) 5 bonding, 0 lone
20.
Which ionic compound has the largest lattice energy?
(A) LiF
(B) BeO
(C) KBr
(D) CaS
21.
When 1.0 mole of H2O2 decomposes to form H2O and O2, 103 kJ of energy is released. Given the bond
energies below, what is the bond energy of the O–O single bond in H2O2?
Bond
Bond Energy, kJ•mol
1
H–O
463
O=O
498
–
22.
Which species has a different number of pi bonds
thanthe others?
(A) C2H2
(B) CO2
(C) N2
(D) O3
(A) +395 kJ•mol–1
(B) +249 kJ•mol–1
(C) +146 kJ•mol–1
(D) +103 kJ•mol–1
CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 4
23.
Which molecule is correctly matched with its shape as predicted by VSEPR theory?
(A) PCl3
trigonal pyramidal
(B) OF2
linear
(C) ClF3
trigonal planar
(D) SF6
24.
hexagonal
Which of the following statements regarding structural isomers is correct? They have
(E) the same molecular formula but the atoms are bonded in different ways.
(F) the same molar mass but different atoms in their composition.
(G) the same physical properties but different chemical properties.
(H) different isotopes in their structures.
25. Benzene, C6H6, reacts with oxygen, O2, to form CO2 and H2O. How much O2 is required for the complete
combustion of 1.0 mol C6H6?
(A) 6.0 mol
26.
(B) 7.5 mol
(C) 9.0 mol
(D) 12 mol
The formula for terbium phosphate is TbPO4. The formula for terbium sulfate is
(A) Tb2SO4
(C) Tb2(SO4)3
(B) TbSO4
(D) Tb(SO4)2
27.
A 25.0 mL sample of 0.15 M silver nitrate, AgNO3, is reacted with a 3.58 g sample of calcium chloride,
CaCl2 (M = 111.0). Which of the following statements is true?
(B) Silver nitrate is the limiting reactant and calcium nitrate precipitates.
(C) Silver nitrate is the limiting reactant and silver chloride precipitates.
(D) Calcium chloride is the limiting reactant and calcium nitrate precipitates.
(E) Calcium chloride is the limiting reactant and silver chloride precipitates.
28.
A 3.0 L sample of helium gas is stored in a rigid, sealed container at 25 °C and 1.0 atm pressure. The
temperature is increased to 125 °C. What is the new pressure of the gas?
(A) 0.20 atm
(B) 0.75 atm
(D) 5.0 atm
(C) 1.3 atm
CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 5
29.
The cubic unit cell of a perovskite structure containing atoms of types A, B, and C is illustrated below.
What is the empirical formula of this substance?
= A
= B
= C
(A) ABC (B) ABC3
(C) AB4C6
(D) AB8C12
30.
A 37.5 g piece of gold at 83.0 °C is added to 100. g H 2O at 22.0 °C in a well-insulated cup. What is the
temperature after the system comes to equilibrium? (The specific heat capacity of Au is 0.129 J•g –1•K–1)
(B) 22.7 °C
(B) 23.0 °C
(C) 25.0 °C
31.
(D) 52.5 °C
Given the enthalpy changes:
∆H = –35 kJ•mol–1
∆H = +20 kJ•mol–1
∆H = +15 kJ•mol–1
A+ B C
A+D E+F
F C+E
What is ∆H for the reaction 2A + B + D → 2 F?
(A) 0 kJ•mol–1
(B) –30 kJ•mol–1 (C) –40 kJ•mol–1 (D) –70 kJ•mol–1
32.
What is the oxidation number of C in formaldehyde, CH2O?
(A) –2
32.
34.
(D) +4
(B) 2
(C) 3
(D) 4
Which element has chemical properties most similar to those of P?
(A) N
(B) Al
(C) S
(D) As
Which halogen atom has the greatest electron affinity?
(A) F
35.
(C) +2
What is the value of the quantum number l for a 5p orbital?
(A) 1
33.
(B) 0
(B) Cl
(C) Br
(D) I
Which electronic transition in atomic hydrogen corresponds to the emission of visible light?
(A)
n = 5 n = 2
(C) n = 3  n = 4
(B) n = 1  n = 2
(D) n = 3  n = 1
CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 6
36.
What is the geometry of the chlorate ion, ClO3–?
(A)
trigonal planar
(B) trigonal pyramidal
(C) T-shaped
(D) zigzag
37.
What is the bond order in NO?
(B)
1.0
38.
In the Lewis structure of ozone, O3, what is the formal charge on the central oxygen?
(B) 1.5 (C) 2.0 (D) 2.5
(A) 2–
38.
an
(B) 1–
(C) 0
(D) 1+
Hydrogenation of an alkene converts it to
(A) alkane.
(B) alkyne.
(C) alcohol.
(D) aldehyde.
39.
What is the relationship between the two
compounds below?
CH3CH2CH(CH3)CH2CH3
CH3CH2CH2CH(CH3)CH3
(A) Identical
(B) Stereoisomers
(C) Geometric isomers
(D) Structural isomers
40.
A 20.0 g sample of mercury(II) oxide (HgO, M = 216.6) is heated strongly, causing it to
decompose to metallic Hg and O2 gas. What volume of O2 gas is produced (measured at STP)?
(A) 1.03 L
(B) 2.07 L
(C) 4.14 L
(D) 14.0 L
41.
When 30.0 mL of 0.10 M AgNO3 is added to 30.0 mL of 0.10 M NaCl, aqueous NaNO3
and solid AgCl are formed. How much solid AgCl is produced?
(A)
0.0030 mol
(C) 0.030 mol
(B) 0.0060 mol
(D) 0.060 mol
42.
How much Sr(OH)2 • 8 H2O (M = 265.76) is needed to prepare 250.0 mL of solution in
which [OH–] = 0.100 M?
(A)
3.32 g (B) 6.64 g
(C) 9.97 g
(D) 13.3 g
43.
A 10.00 g sample of a compound containing only carbon, hydrogen, and oxygen forms
23.98 g CO2 and 4.91 g H2O upon complete combustion. What is the empirical formula of the
compound?
(A) C2HO
(B) C3H3O
(C) C6H3O2
(D) C6H6O
CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 7
44. Which of the following is a nonelectrolyte in aqueous solution?
(A) H2SO4
(B) NaC2H3O2 (C) K2CO3
(D) CH2O
45.
40.0 mL of 0.200 M aqueous NaOH is added to 200.0 mL of 0.100 M aqueous NaHCO 3 in a flask
maintained at 25 ºC. Neglecting the effects of dilution, what is q for this reaction?
∆Hºf, kJ mol–1
OH–(aq)
–230
HCO3–(aq)
–692
CO32–(aq)
–677
H2O(l)
–286
(A) –41 J
(B) –74 J
(C) –330 J
(D) –820 J
46. In a well-insulated vessel, 50.0 g ice at 0.0 ºC is added to 350. g water at 32.0 ºC. What is the final
temperature when the mixture reaches equilibrium? (The heat of fusion of ice is 334 J g –1.)
(A) 18.0 ºC
(C) 22.0 ºC
(B) 20.6 ºC
(D) 28.0 ºC
47.
The bond dissociation enthalpies of the H–H bond and the H–Cl bond are 435 kJ mol–1 and 431 kJ mol–1,
respectively. The ∆Hºf of HCl(g) is –92 kJ mol–1. What is the bond dissociation enthalpy of the Cl–Cl bond?
(A) 88 kJ mol–1
(C) 188 kJ mol–1
48.
(B) 96 kJ mol–1
(D) 243 kJ mol–1
Which statement about chemical reaction mechanisms is correct?
A. The overall rate law can be determined from any step in the mechanism.
B. The rate of a reaction is the rate of the fastest elementary step of its mechanism.
C. The chemical equation for the sum of all the elementary steps is the chemical equation of the
overall reaction.
49.
D. Species that are produced and subsequently consumed in the mechanism serve as catalysts for the
reaction.
When the equation
ClO2(aq) + OH–(aq)
ClO2–(aq) + ClO3–(aq) + H2O(l) is balanced, what is the ratio of the coefficient of
ClO2 to that of ClO3–?
(A) 1 : 1
(B) 2 : 1
(C) 3 : 1
(D) 3 : 2
CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 8
50.
Which of the following statements is best supported by the data from Rutherford’s experiment of scattering
alpha particles with a thin metal foil?
A. The mass and positive charge of an atom are concentrated in its center.
B. Electrons in atoms occupy only certain specific energy levels.
C. Moving particles can also be described as waves.
D. Atoms of a given element do not all have identical masses.
51.
As atomic number increases from 11 to 15, the atomic radii of the elements
(A) increase
(B) decrease
(C) increase, then decrease
(D) decrease, then increase
52.
Nitrogen has a greater first ionization energy than oxygen. What is the best explanation for this
observation?
A. Nitrogen is more electronegative than oxygen.
B. A nitrogen atom is smaller than an oxygen atom.
C. The electron ionized from nitrogen experiences less electron-electron repulsion than the electron
ionized from oxygen.
D. The electron ionized from nitrogen is a 2s electron, while the electron ionized from oxygen is a 2p
electron.
53.
Which set of quantum numbers n, l, ml, ms is invalid?
(A) 1, 1, 0, –½
(D) 4, 3, 2, –½
(C) 3, 1, 0, +½
54.
(B) 2, 0, 0, +½
Which molecule is nonpolar, yet contains polar covalent bonds?
(A) CO2
(B) HCN
(C) NH3
(D) P4
55.
The nitrite ion, NO2–, can be represented as a resonance hybrid of two significant Lewis structures. Which
statements about this are correct?
I.
II.
56.
The two resonance structures contribute equally to the structure.
The formal charge of nitrogen is zero in both resonance structures.
(A) I only
(B) II only
(C) Both I and II
(D) Neither I nor II
What is the molecular geometry of IF3?
(A) Trigonal planar
(C) T-shaped
(B) Trigonal pyramidal
(D) Tetrahedral
CHM 2041
ACS Final Review
SARC Tutor: Laura Sawires
Page 9
57.
Which contains sp3-hybridized carbon atoms?
(B) Benzene, C6H6
(C) Ethene, C2H4
58.
(B) Ethane, C2H6
(D) Ethyne, C2H2
How many sigma bonds are in 2-butyne (CH3C CCH3)?
(A) 3
(B) 6
(C) 9
(D) 11