AP Chemistry Holiday Review for Midterm: Due Friday 1/8
This is a TEST GRADE!!!
Calculator may be used. CLEARLY SHOW THE METHOD USED AND STEPS INVOLVED IN ARRIVING AT YOUR ANSWERS.
It is to your advantage to do this, because you may earn partial credit if you do and you will receive little or no credit if you do
not. Attention should be paid to significant figures. Also, cancel out any ions not participating in reaction in chemical equations.
Unit 1: Review of the Basics: Mole, Combustion Analysis, Lab Techniques, History of the Atom, Nomenclature, %
error, % composition, Stoichiometry
1) The simplest formula for an oxide of nitrogen that
is 36.8 percent nitrogen by weight is
(A) N2O
(D) N2O3
(B) NO
(E) N2O5
(C) NO2
2) When a hydrate of Na2CO3 is heated until all the
water is removed, it loses 54.3 percent of its mass.
The formula of the hydrate is
(A) Na2CO3 . 10 H2O
(B) Na2CO3 . 7 H2O
(C) Na2CO3 . 5 H2O
(D) Na2CO3 . 3 H2O
(E) Na2CO3 . H2O
3) 1.00 mole of four different compounds containing
element X were analyzed and found to contain 36.0
grams, 54.0 grams, 72.0 grams, and 108 grams,
respectively. A possible atomic weight of X is
a) 13.5
b) 18.0
c) 25.0
d) 72.0
e) 108
4) 4NH3(g) + 5O2(g)  4NO(g) + 6H2O (g)
In the reaction above, 3.10g of NH3 reacts with 2.50g
of O2. What is the theoretical yield of NO?
a) 1.88 g
b) 5.46 g
c) 8.20 g
d) 24.0 g
e) 120 g
Free Response:
The following questions refer to a laboratory activity
designed to determine concentration of lead ions in a
solution of lead (II) nitrate using gravimetric
analysis. In the experiment, a 50.0mL sample of the
Pb(NO3)2 solution was added to an excess of
potassium iodide solution. The resulting precipitate,
PbI2, was collected by vacuum filtration, dried in a
drying over, and weighed. Assume that: both solutions
were pure; no decomposition took place in the drying
oven; the filer did not allow any PbI2 through; all lead
is lead (II); an analytical balance was used to weigh
the product.
a) If 2.310 g of PbI2 were collected, how many
grams of lead (II) nitrate must have been in the
50.0mL sample?
b) What is the molarity of the lead (II) nitrate
solution?
c) How many grams of lead (II) ion were in the lead
(II) nitrate solution?
d) What is the minimum number of moles of
potassium iodide that must be present in solution
to assure a complete precipitation of all lead from
solution?
e) If the solid PbI2 on the filer paper was not
thoroughly rinsed with distilled water prior to
drying, what implications would that have on your
answer in question (a)? Defend your response.
Unit 2: Reaction Prediction and Acid Base Reactions: Rxn Prediction, AB Stoichiometry, Molarity and Ion
Concentrations
1. How many milliliters of 11.6-molar HCl must be
diluted to obtain 1.0 liter of 3.0-molar HCl?
(A) 3.9 mL
3. A 1.0L sample of an aqueous solution contains 0.10
(B) 35 mL
added to the solution in order to precipitate all of
(C) 260 mL
minimum number of moles of AgNO3 that must be
the Cl¯ as AgCl(s) ? (Assume that AgCl is insoluble.)
(D) 1,000 mL
(A) 0.10 mol
(E) 3,900 mL
(B) 0.20 mol
2. How many moles of solid Ba(NO3)2 should be added
to 300. milliliters of 0.20-molar Fe(NO3)3 to increase
the concentration of the NO3¯ ion to 1.0-molar?
(Assume that the volume of the solution remains
constant.)
(A) 0.060 mole
(D) 0.30 mole
(B) 0.12 mole
mol of NaCl and 0.10 mol of CaCl2. What is the
(E) 0.40 mole
(C) 0.24 mole
(C) 0.30 mol
(D) 0.40 mol
(E) 0.60 mol
4. What is the final concentration of barium ions,
[Ba2+], in solution when 100. mL of 0.10 M BaCl2(aq) is
mixed with 100. mL of 0.050 M H2SO4(aq)?
A) 0.00 M
B) 0.012 M
C) 0.025 M
D) 0.075 M
E) 0.10 M
Free Response:
1. (a) A 0.1M solution of ammonium chloride is mixed with a 0.1M solution of potassium hydroxide.
(i) Balanced equation:
(ii)
What evidence of a reaction will be observed? Explain.
(b) Carbon dioxide is bubbled into water.
(i) Balanced equation:
(ii)
Will the resulting product have a pH < 7, pH > 7, or pH = 7? Explain.
(c) A 0.1M solution of potassium iodide is mixed with a 0.1M solution of lead II nitrate.
(i) Balanced equation:
(ii)
What evidence of a reaction will be observed? Explain.
(d)
drops of liquid dinitrogen trioxide are added to distilled water.
(e)
solid magnesium carbonate is heated.
Unit 3: Redox: Oxidation and Reduction, Predicting, Balancing in an Acid, Balancing in a Base
Balance the following equations (atom and charge balance)
(1) A concentrated solution of hydrochloric acid is added to solid potassium permanganate.
(2) Solutions of tin(II) chloride and iron(III) chloride are mixed.
(3) hydrogen peroxide solution is added to acidified potassium iodide solution.
(4) a solution containing tin(II) ions is added to an acidified solution of potassium dichromate.
Free Response:
1. Answer the following questions about BeC2O4(s) and its hydrate.
(a) Calculate the mass percent of carbon in the hydrated form of the solid that has the formula BeC2O4•3H2O.
(b) When heated to 220.⁰C, BeC2O4•3H2O(s) dehydrates completely as represented below.
BeC2O4•3H2O(s)  BeC2O4(s) + 3 H2O(g)
If 3.21 g of BeC2O4•3H2O(s) is heated to 220.⁰C calculate
(i)
the mass of BeC2O4(s) formed
(c) A 0.345 g sample of anhydrous BeC2O4, which contains an inert impurity, was dissolved in sufficient water to
produce 100. mL of solution. A 20.0 mL portion of the solution was titrated with KMnO 4(aq). The balanced
equation for the reaction that occurred is as follows.
16 H+(aq) + 2 MnO4-(aq) + 5 C2O42-(aq)  2 Mn2+(aq) + 10 CO2(g) + 8 H2O(l).
The volume of 0.0150 M KMnO4(aq) required to reach the equivalence point was 17.80 mL.
(i)
Identify the reducing agent in the titration reaction.
(ii)
For the titration at the equivalence point, calculate the number of moles of each of the following that
reacted:
MnO4-(aq)
and
C2O42-(aq)
(iii) Calculate the total number of moles of C2O42-(aq) that were present in the 100. mL of prepared solution.
(iv) Calculate the mass percent of BeC2O4(s) in the impure 0.345 g sample.
Unit 4: Gases: Gas Laws, KMT, Gas Stoichiometry
1) A sample of 3.0 grams of an ideal gas at 121 °C and
1.0 atmosphere pressure has a volume of 1.0 Liters.
Which of the following expressions is correct for the
molar mass of the gas? The ideal gas constant, R, is
0.08 (L-atm) / (mole K).
(A) [(0.08)(400)] / [(3.0)(1.0)(1.5)]
(B) [(l.O)(l.5)] / [(3.0)(0.08)(400)]
(C) [(O.O8)(1.0)(1.5)] / [(3.0)(400)]
(D) [(3.0)(0.08)(400)] / [(1.0)(1.5)]
(E) [(3.0)(0.08)(1.5)] / (1.0)(400)]
2) Two flexible containers for gas are at the same
temperature and pressure. One holds 0.50 gram of
hydrogen and the other holds 8.0 grams of oxygen.
Which of the following statements regarding these
gas samples is FALSE?
(A) The volume of the hydrogen container is
the same as the volume of the oxygen
container.
(B) The number of molecules in the hydrogen
container is the same as the number of
molecules in the oxygen container.
(C) The density of the hydrogen sample is less
than that of the oxygen sample.
(D) The average kinetic energy of the
hydrogen molecules is the same as the
average kinetic energy of the oxygen
molecules.
(E) The average speed of the hydrogen
molecules is the same as the average speed of
the oxygen molecules.
3) Equal numbers of moles of He(g), Ar(g), and Ne(g)
are placed in a glass vessel at room temperature. If
the vessel has a pinhole-sized leak, which of the
following will be true regarding the relative values of
the partial pressures of the Gas remaining in the
vessel after some of the gas mixture has effused?
A) PHe < PNe < PAr
B) PHe < PAr < PNe
C) PNe < PAr < PHe
D) PAr < PHe < PNe
E) PHe = PAr = PNe
4) Which of the following Gas deviates most from
ideal behavior?
A) SO2
B) Ne
C) CH4
D) N2
E) H2
5) A chunk of calcium carbide is placed into a
container of water, and the acetylene gas that is
nearly full. The gas was allowed to sit for several
minutes. The collection tube was then adjusted so
that the level of water in the tube was equal to the
level of the water outside of the tube. The volume of
gas was determined to be 47 mL and the temperature
of the water was 22°C. The barometric pressure in
the laboratory was 745 mmHg. The vapor pressure at
22°C is 19.4mmHg.
formed is bubbled through water into an inverted
graduated cylinder. Then pressure inside the
graduated cylinder is 800 mmHg and the temperature
is 27°C. What is the partial pressure exerted by the
acetylene gas? (The vapor pressure of water at 27°C
is 27 mmHg).
A) 800 mmHg
B) 827 mmHg
(A) Calculate the number of moles of
C) 27 mmHg
hydrogen gas produced.
D) 773 mmHg
(B) Explain why it was necessary to allow the
E) 54 mmHg
gas to sit in the tube for several minutes
before determining its volume.
Free Response:
(C) Explain why it was necessary to adjust
A small sample of mossy zinc was placed into a
reaction vessel, as show in the figure. Hydrochloric
the level of the tube so that water levels
acid was added, and the hydrogen gas that was
inside and outside of it were the same.
(D) Explain why the vapor pressure of water
generated was bubbled through water into a gas
is given.
collection tube filled with water. When the reaction
reached completion, the gas collection tube was
Unit 5: Thermochemistry: Enthalpy, Entropy, Gibbs Free Energy, Hess’s Law, Heat Transfer, Work and Energy
1. A cube of ice is added to some hot water in a rigid,
insulated container, which is then sealed. There is no heat
exchange with the surroundings. What has happened to the
total energy and the total entropy when the system
reaches equilibrium?
Energy
Entrop.
(A)
Remains constant
Remains constant
(B)
Remains constant
Decreases
(C)
Remains constant
Increases
(D)
Decreases
Increases
(E)
Increases
Decreases
2. When solid ammonium chloride, NH4Cl(s) is added to water at 25 °C, it
dissolves and the temperature of the solution decreases. Which of the
following is true for the values of ΔH and ΔS for the dissolving process?
ΔH
ΔS
A Positive
Positive
B) Positive
Negative
C) Positive
Equal to zero
D Negative Positive
E) Negative Negative
3) For which of the following is ΔH most nearly equal to ΔE?
a. C2H5OH (l)  C2H5OH (g)
b. N2O4 (g)  2NO2 (g)
c. H2 (g) + ½ O2 (g)  H2O (g)
d. H2 (g) + Cl2 (g)  2HCl (g)
e. BaO2 (s)  2BaO2 (s) + ½ O2 (g)
Free Response:
1.
C6H5OH(s) + 7 O2(g)  6 CO2(g) + 3 H2O(l)
When a 2.000-gram sample of pure phenol, C6H5OH(s), is completely burned according to the equation above, 64.98
kilojoules of heat is released. Use the information in the table below to answer the questions that follow.
Substance
Standard Heat of
Absolute Entropy,
Formation, ∆Hºf;
Sº, at 25ºC
at 25ºC (kJ/mol)
(J/mol-K)
C(graphite)
0.00
5.69
CO2(g)
-393.5
213.6
H2(g)
0.00
130.6
H2O(l)
-285.85
69.91
O2(g)
0.00
205.0
C6H5OH(s)
?
144.0
(a) Calculate the molar heat of combustion of phenol in kilojoules per mole at 25°C.
(b) Calculate the standard heat of formation, ∆Hºf, of phenol in kilojoules per mole at 25ºC.
(c) Calculate the value of the standard free-energy change, ∆Gº, for the combustion of phenol at 25ºC.
(d) If the volume of the combustion container is 10.0 liters, calculate the final pressure in the container when the
temperature is changed to 110.ºC. (Assume no oxygen remains unreacted and that all products are gaseous.)
Unit 6: Kinetics: Rates of Reaction, Arrhenius Equation, Differential Rate Laws, Integrated Rate Laws, Reaction
Mechanisms
1) If a reaction, 2A + 3B  products, is first
b.
It will increase by two times
order for A and second order for B, the rate
c.
It will increase by three times
law for the overall reaction will be written as
d. It will increase by six times
Rate =
e.
It will increase by nine times
A) k[A] [B]
B) k[A] [B]2
3) Nitrogen dioxide decomposes according to
2
2
2
3
C) k[A] [B]
D) k[A] [B]
the following reaction:
2NO2 (g)  2NO (g) + O2 (g)
2
E) k[A] [B]
For the initial rate data given, what is the
value for k in the rate law?
2) The rate law for the reaction 2A + B  C was
2
a) 0.010 M
found to be Rate = k[A] [B] . If the
b) 7.1 x 10-3 s-1
concentration of B is tripled, what will happen
c) 3.5 x 10
to the rate of the reaction?
d) 0.71 M—1 s-1
a.
It will stay the same
e) 4
-3
s-1
A. Mole A vs time if the reaction is first
order for A
B. 1/[A] vs time if the reaction is first order
for A
C. 1/[A]2 vs time if the reaction is second
1)
order for A
2)
D. ln [A] vs time if the reaction is first
3)
order for A
4)
E. ln [A] vs time if the reaction is second
order for A
Free Response:
The proposed mechanism for the reaction in this
question is shown below:
4) 2H2O2 (l)  2H2O (l) + O2 (g)
(any forward direction is k1 and reverse k-1)
Hydrogen peroxide decomposes according to
Step 1: 2 NO(g)   N2O2 (g)
(fast)
the reaction above, which is first order for
Step 2: N2O2 (g) + H2 (g)  H2O2 (g) + N2(g) (slow)
H2O2, and has a half-life of 18.0 minutes. If
Step 3: H2(g) + H2O2 (g)   2H2O
(fast)
an H2O2 solution that was initially 0.80 M is
allowed to decompose for 72 minutes, what
will the concentration be at that time?
a.
0.80M
b. 0.40M
c.
0.20M
d. 0.10M
e.
0.05M
(A) Write the balanced equation for this
reaction.
(B) Identify the rate – determining step.
(C) Write a rate law that is most consistent with
this mechanism.
(D) Based on your rate law, determine the effect
of doubling the concentration of NO (while
maintaining constant amounts of all other
5) Which of the following would produce a
reactants) on the reaction rate.
linear graph for the following reaction? A
 product(s)
Unit 7: General Equilibrium : Equilibrium Expressions, Equilibrium Constants, K vs Q, Neglect x, ICE, Le Chat
1) 2CO2 (g)   2CO (g) + O2 (g)
After the equilibrium represented above is
established, some pure O2 (g) is injected into
the reaction vessel at constant temperature.
After equilibrium is reestablished, which of
d) The amount of O2 (g) in the reaction
vessel
e) The amount of CO (g) in the reaction
vessel
2) 2SO2(g) + O2(g)  2SO3 (g)
the following has a lower value compared to
∆H° - -197 kJ
its value at the original equilibrium?
Which of the following changes alone
a) Keq for the equation
would cause a decrease in the value of Keq for
b) The total pressure in the reaction
the reaction represented above?
vessel
c) The amount of CO2 (g) in the reaction
vessel
a) Decreasing the temperature
b) Increasing the temperature
c) Decreasing the volume of the
reaction vessel
d) Increasing the volume of the
5) At 373 K, the reaction below has an
equilibrium constant, Kc = 2.19 x 10-10
reaction vessel
e) Adding a catalyst
COCl2 (g)   CO (g) + Cl2 (g)
3) N2 (g) + 3 H2 (g)   2NH3 + energy
After placing a mixture of gases in the reaction
Some N2 and H2 are mixed in a container at 200°C
vessel, the concentrations were measured to be
and the system reaches equilibrium according to
[COCl2] = 3.50 x 10-3 M, [CO] = 1.11 x 10-5M, and [Cl2]
the equation above. Which of the following causes
= 3.25 x 10-6 M. Which statement below accurately
an increase in the number of moles of NH3
describes this reaction?
present at equilibrium?
(a) The reaction is at equilibrium
I.
Decreasing the volume of the container
(b) The reaction is not at equilibrium, and it is
II.
Raising the temperature
III.
Adding a mole of Ar gas at constant
proceeding to the left
(c) The reaction is not at equilibrium, and it is
volume
proceeding to the right
(A) I only
(d) The reaction quotient is equal to Kc
(B) II only
(e) The reaction quotient is less than Kc
(C) I and III only
(D) II and III only
Free Response:
(E) I, II, and III
At 25ºC the solubility product constant, Ksp, for
4) I2 (g) + Br2 (g)   2 IBr (g)
strontium sulfate, SrSO4, is 7.610-7. The solubility
In the reaction shown above, 0.50 moles of Br2
product constant for strontium fluoride, SrF2, is
and 0.50 moles of I2 are placed in an evacuated
7.9´10-10.
1.00 L vessel and allowed to reach equilibrium.
What is the value of Kc if the vessel contains
0.84 moles if IBr at equilibrium?
(a) 2.0
(b) 8.8
(c) 11
(d) 110
(e) 130
(a) What is the molar solubility of SrSO4 in pure
water at 25ºC?
(b) What is the molar solubility of SrF2 in pure water
at 25ºC?
(c) An aqueous solution of Sr(NO3)2 is added slowly
to 1.0 litre of a well-stirred solution containing
0.020 mole F- and 0.10 mole SO42- at 25ºC. (You
may assume that the added Sr(NO3)2 solution
does not materially affect the total volume of the
system.)
1.
Which salt precipitates first?
2. What is the concentration of strontium ion,
Sr2+, in the solution when the first precipitate
begins to form?
(d) As more Sr(NO3)2 is added to the mixture in (c) a
second precipitate begins to form. At that stage,
what percent of the anion of the first precipitate
remains in solution?
*We will do this right after break*
3) A 50.0 mL sample of 0.15 M NaOH is added to
Unit 8: Acid Base Equilibrium: AB Reactions,
50.0mL of 0.10M Ba(OH)2. What is the molar
Neutralization Reactions, Salt Hydrolysis, Polyprotic
concentration of OH- (aq) in the resulting
Acids, Dissociation Constants, Ka, Kb, Kw
solution? (assume the volumes are additive).
a.
1) A molecule or an ion is classified as a Lewis
base if it
a.
electrons
e.
Forms a bond by donating a pair of
oxygens (i.e. HAO, HAO2, HAO3), which of
electrons
the following occurs as the number of oxygen
atoms increases?
Has resonance Lewis structures
a.
+
2) What is the H (aq) concentration in 0.05M
-8
HClO (aq)? (The Ka for HClO is 3.0 x 10 )
a.
1.5 x 10
b. 2.5 x 10
c.
-9
3.9 x 10-9
3.9 x 10-3
It is impossible to predict the acid
strength
b. The strength of the acid increases
c.
The strength of the acid decreases
only if A is a nonmetal
-10
d. 3.9 x 10-5
e.
0.55 M
4) For oxoacids that vary only by the number of
d. Accepts a proton from water
e.
0.18 M
d. 0.36 M
b. Forms a bond by accepting a pair of
c.
b. 0.13 M
c.
donates a proton to water
0.10 M
d. The strength of the acid decreases
only if A is a metal
e.
The strength of the acid decreases
whether A is a nonmetal or a metal