AP Chemistry
Practice MC Questions – 1st Semester
1. How many oxygen atoms are contained in 2.74 g of Al2 (SO4 )3 ?
A) 12
B) 6.02 1023
C) 7.22 1024
D) 5.79 1022
E) 8.0110 3
2. The ΔE of a system that releases 12.4 J of heat and does 4.2 J of work on the
surroundings is __________ J.
A) 16.6
B) 12.4
C) 4.2
D) -16.6
E) -8.2
3. A compound that is composed of carbon, hydrogen, and oxygen contains 70.6% C,
5.9% H, and 23.5% O by mass. The molecular weight of the compound is 136 amu.
What is the molecular formula?
A) C8 H8O 2
B) C8 H 4O
C) C4 H 4O
D) C9 H12O
E) C5 H 6O 2
4. What mass in grams of hydrogen is produced by the reaction of 4.73 g of magnesium
with 1.83 g of water?
Mg (s)  2 H2O (l)  Mg(OH)2 (s)  H2 (g)
A) 0.102
B) 0.0162
C) 0.0485
D) 0.219
E) 0.204
5. The total concentration of ions in a 0.250 M solution of HCl is __________.
A) essentially zero. C) 0.250 M
E) 0.750 M
B) 0.125 M
D) 0.500 M
6) A strong electrolyte is one that __________ completely in solution.
A) reacts
B) associates C) disappears D) ionizes
7) A weak electrolyte exists predominantly as __________ in solution.
A) atoms
B) ions
C) molecules
D) electrons E) an isotope
AP Chemistry
Practice MC Questions – 1st Semester
8) Which of the following are weak electrolytes?
HCl
HC2 H 3 O 2
NH 3
KCl
A) HCl , KCl
B) HCl , HC2 H 3 O 2 , NH 3 , KCl
C) HC2 H 3 O 2 , KCl
D) HC2 H 3 O 2 , NH 3
E) HCl , HC2 H 3 O 2 , KCl
9) Combining aqueous solutions of BaI 2 and Na 2 SO 4 affords a precipitate of BaSO 4 .
Which ion(s) is/are spectator ions in the reaction?
A) Ba 2 only
C) Ba 2 and SO 4 2
B) Na  only
D) Na + and I 
E) SO 4 2 and I 
10) The balanced net ionic equation for precipitation of CaCO 3 when aqueous solutions
of Na 2 CO 3 and CaCl 2 are mixed is __________.
A) 2Na + (aq)  CO32 (aq)  Na 2 CO 3 (aq)
B) 2 Na + (aq)  2Cl (aq)  2NaCl (aq)
C) Na + (aq)  Cl (aq)  NaCl (aq)
D) Ca 2+ (aq)  CO 32 (aq)  CaCO 3 (s)
E) Na 2 CO 3 (aq)  CaCl 2 (aq)  2NaCl (aq)  CaCO 3 (s)
11) Which of the following are strong acids?
HI
HNO 3
HF
HBr
A) HF , HBr
B) HI , HNO 3 , HF , HBr
C) HI , HF , HBr
D) HNO 3 , HF , HBr
E) HI , HNO 3 , HBr
12) How many grams of H 3 PO 4 are in 175 mL of a 3.5 M solution of H 3 PO 4 ?
A) 0.61
B) 60
C) 20
D) 4.9
E) 612
AP Chemistry
Practice MC Questions – 1st Semester
13) A 25.5 mL aliquot of HCl (aq) of unknown concentration was titrated with 0.113 M
NaOH (aq). It took 51.2 mL of the base to reach the endpoint of the titration. The
concentration (M) of the acid was __________.
A) 1.02
B) 0.114
C) 0.454
D) 0.113
E) 0.227
14) Aqueous solutions of a compound did not form precipitates with Cl , Br  , I  ,
SO 4 2  , CO 32 , PO 4 3 , OH  , or S2  . This highly water-soluble compound produced the
foul-smelling gas H 2 S when the solution was acidified. This compound is __________.
A) Pb(NO 3 ) 2
B) (NH 4 ) 2 S
C) KBr
D) Li 2 CO 3
E) AgNO3
15) In which reaction does the oxidation number of oxygen increase?
A) Ba(NO 3 ) 2 (aq)  K 2 SO 4 (aq)  BaSO 4 (s)  2KNO 3(aq)
B) HCl (aq)  NaOH (aq)  NaCl (aq) H 2O (l)
C) MgO (s)  H 2 O (l)  Mg(OH) 2 (s)
D) 2 SO 2 (g)  O 2 (g)  2 SO 3 (g)
E) 2 H 2 O (l)  2 H 2 (g)  O 2 (g)
16) Oxidation is the __________ and reduction is the __________.
A) gain of oxygen, loss of electrons
B) loss of oxygen, gain of electrons
C) loss of electrons, gain of electrons
D) gain of oxygen, loss of mass
E) gain of electrons, loss of electrons
17) Which of the following would require the largest volume of 0.100 M sodium
hydroxide solution for neutralization?
A) 10.0 mL of 0.0500 M phosphoric acid
B) 20.0 mL of 0.0500 M nitric acid
C) 5.0 mL of 0.0100 M sulfuric acid
D) 15.0 mL of 0.0500 M hydrobromic acid
E) 10.0 mL of 0.0500 M perchloric acid
18) The value of H for the reaction below is -72 kJ. __________ kJ of heat are
released when 1.0 mol of HBr is formed in this reaction.
H2 (g)  Br2 (g)  2HBr(g)
A) 144
B) 72
C) 0.44
D) 36
E) -72
AP Chemistry
Practice MC Questions – 1st Semester
19. A sample of aluminum metal absorbs 9.86 J of heat, upon which the temperature of
the sample increases from 23.2 °C to 30.5 °C. Since the specific heat capacity of
aluminum is 0.90 J/g-K, the mass of the sample is __________ g.
A) 72
B) 1.5
C) 65
D) 8.1
E) 6.6
20) ΔH for the reaction
IF5 (g)  IF3 (g)  F2 (g)
is __________ kJ, give the data below.
ΔH = -390 kJ
IF(g)  F2 (g)  IF3 (g)
IF(g)  2F2 (g)  IF5 (g)
A) +355
B) -1135
C) +1135
D) +35
E) -35
ΔH = -745 kJ
21) Given the following reactions
N2 (g)  2O2 (g)  2NO2 (g)
ΔH = 66.4 kJ
2NO(g)  O2 (g)  2NO2 (g)
ΔH = -114.2 kJ
the enthalpy of the reaction of the nitrogen to produce nitric oxide
N 2 (g)  O2 (g)  2NO(g)
is __________ kJ.
A) 180.6
B) -47.8
C) 47.8
D) 90.3
E) -180.6
Questions 22–25 refer to the reactions represented below.
(A) H2SeO4(aq) + 2 Cl–(aq) + 2 H+(aq)  H2SeO3(aq) + Cl2(g) + H2O(1)
(B) S8(s) + 8 O2(g)  8 SO2(g)
(C) 3 Br2(aq) + 6 OH–(aq)  5 Br–(aq) + BrO3–(aq) + 3 H2O(l)
(D) Ca2+(aq) + SO42–(aq)  CaSO4(s)
(E) PtCl4(s) + 2 Cl–(aq)  PtCl62–(aq)
22.
23.
24.
25.
A precipitation reaction D
A synthesis reaction. B or E
A reaction in which the same reactant undergoes both oxidation and reduction C
A combustion reaction B
AP Chemistry
Practice MC Questions – 1st Semester
26. In the laboratory, H2(g) can be produced by adding which of the following to 1 M
HCl(aq)?
I. 1 M NH3(aq)
II. Zn(s)
III. NaHCO3(s)
(A) I only
(B) II only
(C) III only
(D) I and II only
(E) I, II, and Ill
2 NH3  NH4+ + NH2–
27. In liquid ammonia, the reaction represented above occurs. In the reaction NH4+ acts
as
(A) a catalyst
(B) both an acid and a base
(C) the conjugate acid of NH3
(D) the reducing agent
(E) the oxidizing agent
H2(g) + Br2(g)  2 HBr(g)
28. At a certain temperature, the value of the equilibrium constant, K, for the reaction
represented above is 2.0105. What is the value of K for the reverse reaction at the
same temperature?
(A) -2.0  10–5
(B) 5.0  10–6
(C) 2.0  10–5
(D) 5.0  10–5
(E) 5.0  10–4
HCO3–(aq) + OH–(aq)  H2O(l) + CO32–(aq)
∆H = –41.4 kJ
29. When the reaction represented by the equation above is at equilibrium at 1 atm and
[CO32–]
25˚C, the ratio
can be increased by doing which of the following?
[HCO3–]
(A) Decreasing the temperature
(C) Adding a catalyst
distilled water
(E) Bubbling neon gas through the solution
(B) Adding acid
(D) diluting the solution with
30. A possible mechanism for the overall reaction represented above is the following.
(1) NO(g) + NO(g)  N2O2(g)
slow
(2) N2O2(g) + O2(g)  2 NO2(g)
fast
Which of the following rate expressions agrees best with this possible mechanism?
[NO]
(A) Rate = k[NO]2
(B) Rate = k [O ]
2
[NO]2
(C) Rate = k [O ]
(D) Rate = k[NO]2[O2]
2
(E) Rate = k[N2O2][O2]
AP Chemistry
Practice MC Questions – 1st Semester
31. Which of the following is a correct statement about reaction order?
(A) Reaction order can only be a whole number.
(B) Reaction order can be determined only from the coefficients of the balanced
equation for the reaction.
(C) Reaction order can be determined only by experiment.
(D) Reaction order increases with increasing temperature.
(E) A second-order reaction must involve at least two different compounds as
reactants.
Rate = k[M][N]2
32. The rate of a certain chemical reaction between substances M and N obeys the rate
law above. The reaction is first studied with [M] and [N] each 1  10–3 molar. If a
new experiment is conducted with [M] and [N] each 2  10–3 molar, the reaction rate
will increase by a factor of
(A) 2
(B) 4
(C) 6
(D) 8
(E) 16
2 N2H4(g) + N2O4(g)  3 N2(g) + 4 H2O(g)
33) When 8.0 g of N2H4 (32 g mol-1) and 92 g of N2O4 (92 g mol-1) are mixed together
and react according to the equation above, what is the maximum mass of H2O that
can be produced?
(A) 9.0 g
(B) 18 g
(C) 36 g
(D) 72 g
(E) 144 g
34) Bond enthalpy is __________.
A) always positive
B) always negative
C) sometimes positive, sometimes negative
D) always zero
Use the table below to answer the questions that follow.
35) The value of S for the decomposition of POCl3 into its constituent elements,
2POCl3 (g)  P2 (g)   2 (g)  3Cl2 (g)
is __________ J/K∙ mol.
A) +771.0
B) +442.0
C) -321.0
D) -771.0
E) +321.0
AP Chemistry
Practice MC Questions – 1st Semester
36) The value of H for the decomposition of calcium chloride into its constituent
elements,
CaCl2 (s)  Ca(s)  Cl2 (g)
is __________ kJ/mol.
A) -0.00
B) -397.9
C) +397.9
D) -795.8
E) +795.8
37) The value of G at 25 C for the formation of POCl3 from its constituent
elements,
P2 (g)  O2 (g)  3Cl2 (g)  2POCl3 (g)
is __________ kJ/mol.
A) -1,108.7 B) +1,108.7 C) -606.2
D) +606.2
E) -1,005
38) The first law of thermodynamics can be given as __________.
A) ΔE = q + w
 nH (products)   mH (reactants)
B) H
rxn 
f
f
C) for any spontaneous process, the entropy of the universe increases
D) the entropy of a pure crystalline substance at absolute zero is zero
E)  S = qrev/T at constant temperature
39) Of the following, only __________ is not a state function.
A) S
B) H
C) q
D) E
E) T
40) The entropy of the universe is __________.
A) constant
B) continually decreasing
C) continually increasing
D) zero
E) the same as the energy, E
41) The normal boiling point of ethanol (C2H5OH) is 78.3 °C and its molar enthalpy of
vaporization is 38.56 kJ/mol. What is the change in entropy in the system in J/K when
97.2 grams of ethanol at 1 atm condenses to a liquid at the normal boiling point?
A) -81.4
B) -4.5
C) 38.6
D) 81.4
E) -231