Download honors chemistry harvard-westlake second semester final exam

 HONORS CHEMISTRY
HARVARD-WESTLAKE
SECOND SEMESTER
FINAL EXAM REVIEW
At the end of the semester, a 10th-grade chemistry teacher asked her students what was the most
important thing that they learned in lab. A student promptly raised his hand and said,
"Never lick the spoon."
FINAL EXAM MATERIALS 1 FINAL EXAM MATERIALS 2 Final Exam Review
How are you going to prepare for the Final Exam?
The best preparation for the final exam is consistent study habits and effort throughout the year. We know that
a lot of material has gone down the lab sink, so to speak, and so we also have some suggestions for areas you should
concentrate on as you prepare. Pay close attention to the listing below. The items are given as things you should be
able to do if you intend to do well on the exam.
A brief description of the final exam format would be "business as usual, but more of it". The exam consists
of 30 multiple choice questions, 4 major required problems, your choice of 4 out of 6 minor problems, and your
choice of 1 out of 32 essays. The essays are somewhat more involved than usual. For the exam you will be provided
with a periodic table, an electronegativity table, the Standard Reduction Potential table, the activity series, the
solubility rules, values of R (the gas constant) and the value for F (the Faraday number)
The exam is worth approximately 110 points.
Following the listing of topics, you will find a "sample" exam. Most of the questions have been drawn from
earlier work. The "exam" is intended for practice only and should not be used to gauge the specific content of the
real thing. On the other hand, no attempt has been made to select problem areas which will not appear on the exam.
The Topics
Unit 1
-you should be familiar with the Rutherford experiment and the conclusions that
it led to
-you should be able to describe the number and type of each particle in a given
atom or ion
-you should be able to name binary and ternary compounds
-you should be able to write chemical formulas from the names of binary and
ternary compounds
-you should be able to calculate molar mass (g/mol)
-you should be able to change g to mol and mol to g
-you should be able to do simple % composition calculations
Unit 2
-you should be able to complete and balance and identify types of chemical
reactions, including non-trivial redox
Unit 3
-you should be able to do mass-mass stoichiometry
-you should be able to calculate the Molarity of a given substance in solution
Unit 4
-you should be able to identify some differences between classical atomic theory
and quantum theory
-you should be able to write correct electron configurations for elements up to
Z = 70
-you should be able to compare major periodic properties for elements (size,
ionization energy, etc.), and interpret their effects on chemical or physical
properties of elements
FINAL EXAM MATERIALS 3 Unit 5
-you should be able to use Hess' Law, either by adding chemical reactions or by
using Hf data, to determine the enthalpy change for a reaction
-you should be able to identify exothermic and endothermic reactions and give
appropriate reaction energy diagrams for each
-you should be able to do stoichiometric calculations involving enthalpy changes
-given enthalpy and entropy data, you should be able to determine which
reactions in a group are likely to be more spontaneous
-you should be able to determine the free energy change for a process given
enthalpy and entropy data
Unit 6
-you should be able to identify correct Lewis structures for atoms and
simple molecules and ions
-you should be able to distinguish between the major types of bonding: ionic and
covalent
-you should be able to determine the net polarity of a molecule from a diagram of
its structure
-you should be able to identify the type of hybridization of the central atom in a
simple molecule or ion
-you should be able to predict the presence of hydrogen bonding
Unit 7
-you should be able to make qualitative judgments about the vapor pressure of a
liquid
-you should be able to solve simple partial pressure problems
-you should be able to apply Boyle's or Charles' Laws to predict the
pressure/volume behavior of a gas system
-you should be able to apply the ideal gas law to solve problems, including
stoichiometry
Unit 8
-you should be able to calculate the molality of a given substance in solution
-you should be able to find the freezing point of a solution
-you should be able to determine the molar mass of an unknown substance from
freezing point depression data
Unit 9
-you should be able to write rate law expressions from initial rate and
concentration data and evaluate the rate constant
-you should be able to discuss aspects of collision theory
-you should be able to complete a consistent mechanism for a simple reaction
given the rate law and appropriate data
Unit 10
-you should be able to write equilibrium constant expressions for reactions and
evaluate them given appropriate data
-you should be able to apply LeChâtelier's Principle in predicting the effect that
changes will have on the state of a system at equilibrium, including the effects
of catalysts
-you should be able to express the solubility of a solid in water given its Ksp (and
the reverse)
-you should be able to predict qualitatively and quantitatively whether a
precipitate will form when ions are mixed
FINAL EXAM MATERIALS 4 Unit 11
-you should be able to balance or complete nuclear reactions
-you should be able to calculate the amount of an isotope that will remain after a
specified period of time
Unit 12
-you should know some of the properties of acids and bases
-you should be able to use Ka in calculations to determine pH and % dissociation
of a weak acid solution
-you should be able to distinguish among common strong/weak acids and bases
-you should know how a buffer solution is prepared and how it functions (not to
mention why)
Unit 13
-you should be able to calculate E o for an electrochemical cell and correctly
interpret a diagram for a galvanic cell (flow of electrons, anode,
cathode, etc.)
-you should be able to predict the products of the electrolysis of a dilute
aqueous salt solution using inert electrodes
-you should be able to apply Faraday's law to a problem involving plating or
electrolysis in water solutions
That's all there is!
Sample Final Exam--Some typical multiple choice
1. The percent, by mass, of phosphorus in Ca3(PO4)2 is
a. 10% b. 20% c. 30% d. 40% e. 50%
2. How many neutrons are in an atom of rubidium with a mass number of 87?
a. 37 b. 74 c. 50 d. 87 e. 85
3. What product is expected at the cathode when a dilute solution of sodium chloride is electrolyzed using inert
electrodes?
a. Na b. Cl2 c. O2 d. H2
4. Rutherford, Geiger and Marsden arrived at a model for the atom different from that of J. J. Thomson. In it
a. electrons are surrounded by a dense mass of protons and neutrons
b. neutrons are positioned
between the protons electrons to keep them apart
c. electrons orbit a very dense nucleus containing
protons and neutrons
d. the nucleus takes up much of the volume of the atom
5. When copper and zinc are placed in contact in a moist environment, which reaction is likely to occur?
a. Cu2+ + Zn  Cu + Zn2+
b. Zn + H2O  ZnO + H2
d. Cu + Zn2+  Cu2+ + Zn
c. Cu + H2O  CuO + H2
6. An atom of element X has the electron configuration 1s22s22p63s2 and element Y has the electron
configuration 1s22s22p63s23p5. The formula for a compound of these two elements is:
a. X2Y b. XY c. XY3 d. XY2 e. X12Y17
7. The correct electron dot symbol for Ga is
FINAL EXAM MATERIALS 5 8. As one moves down the periodic table, which of the following properties increases?
a. electron affinity b. ionization energy c. electronegativity
d. atomic radius
For the following question, compare the assertion (top) and the reason (bottom) and select the appropriate answer
from the options given below:
a. both are true and reason fits the assertion
b. both are true but reason does not explain assertion
c. only the assertion is true
d. only the reason is a true statement
e. both are false
9. The first ionization energy of Li is less than that of Na
BECAUSE
Li is a smaller atom than Na.
10. The hybrid orbitals of the carbon atom in methane, CH4 , are called
a. sp b. sp2 c. sp3 d. sp4
11. Of the following molecules, all of which have polar bonds, the non-polar molecule is
a. HCl (linear) b. H2O (v-shaped) c. NH3 (trigonal pyramid)
d. CCl4 (tetrahedron)
12. For which of the following transformations is hydrogen bonding expected to be the strongest force to overcome?
a. boiling ICl b. melting CH3OH c. subliming CO2
d. boiling ClO2 e. melting I2
13. A liquid will boil when
a. its vapor pressure is less than atmospheric pressure
b. its critical pressure exceeds atmospheric pressure
c. its critical temperature equals room temperature
d. its vapor pressure equals atmospheric pressure
e. its temperature reaches the triple point
14. A volume of 48 mL of hydrogen gas is collected when the pressure is 600 mm Hg (to the nearest mm). If all
other conditions remain constant what volume will this gas occupy when the pressure becomes 800 mm Hg
(also to the nearest mm)?
a. less than 36 mL b. 36 mL c. 48 mL d. 64 mL
15. The volume occupied by 0.50 mole of propane gas, at a temperature of 27oC and a pressure of 202.6
kPa is best expressed by which of the following?
a. (0.50 x 8.31 x 27)/202.6 b. (0.50 x 8.31 x 300)/202.6
c. (0.50 x 8.31 x 273)/300 d. (0.50 x 8.31 x 300)/(202.6 x 760)
e. (0.50 x 8.31 x 27)/(202.6 x 760)
16. Given these two reaction heats:
S(s) + O2(g) SO2(g) H = -297 kJ
S(s) + 3/2 O2(g)  SO3(g) H = -438 kJ
What is the heat of reaction for
2 SO2(g) + O2(g)  2 SO3(g)
a. -282 kJ b. -297 kJ c. -735 kJ d. -890 kJ e. -1470 kJ
FINAL EXAM MATERIALS under the same conditions?
6 17. Consider the reaction below:
1.7 kJ + NaCl(s) + H2O(ℓ)  Na+(aq) + Cl-(aq)
Which of the following combinations for H and S is correct?
a. +,- b. -,+ c. -,- d. +,+
18. How many grams of sodium hydroxide pellets are required to prepare 50 mL (to the nearest 1 mL) of a 0.15 M
solution?
a. 0.30 b. 2.0 c. 3.0 d. 20 (to the nearest 1)
19. What is the freezing point of a 0.78 m water solution of non-volatile molecular solute? (Kf = 1.86)
a. -0.400oC b. -0.745oC c. -1.45oC d. -2.26oC
e. insufficient information
20. A solution of a sodium salt that will form a precipitate with 0.1 M Pb(NO3)2 but NOT with 0.1 M Ba(NO3)2 is
a. NaCl b. Na2CO3 c. Na2SO4 d. Na3PO4 e. Na2SO4
21. The [H3O+] of a solution is 2.3 x 10-4 M. The pH of the solution lies between
a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 4 and 5
22. Which compound is a weak base?
a. sodium hydroxide, NaOH
b. potassium hydroxide, KOH
c. aluminum hydroxide, Al(OH)3
d. lithium hydroxide, LiOH
23. At the "end-point" of an acid-base titration, which of the following would always be true?
a. the volume of acid equals the volume of base
b. the solution is neutral (pH = 7)
c. [H+] = [OH-]
d. moles of H+ added equals moles of OH- that were present
e. none of the above
24. Which one of the following is not a property you would expect of an acid?
a. reacts with magnesium to give H2
b. tastes sour
c. water solution conducts electricity
d. feels slippery
25. When properly balanced with the smallest integer coefficients for acidic solution, the sum of all the coefficients
in the half reaction below will be:
(H+)
CrO3  Cr3+
a. 12
b. 14
c. 8
d. 5
e. none of these
26. What is the standard voltage, E o, for this electrochemical cell?
Cr(s) + 3 Ag+(aq)  Cr3+(aq) + 3 Ag(s)
Half reaction
Ag (aq) + e-  Ag(s)
Cr3+(aq) + 3 e-  Cr(s)
+
a. -0.06 v
b. +0.06 v
FINAL EXAM MATERIALS c. -1.54 v
Eo
+0.80 V
-0.74 V
d. +1.54 v
7 27. Consider these half-cell reactions:
2 AgO + H2O + 2 e-  Ag2O + 2 OHZn(OH)2 + 2 e-  Zn + 2 OH-
E o = -0.57 V
E o = -1.25 V
A galvanic cell made from these half-cells:
a. would have a cell potential of -0.68 v
b. would be in a state of equilibrium
c. would consume zinc metal and produce Ag2O
d. would have a cell potential of -1.82 v
e. would work only under acidic conditions
28. In an electrolysis cell, the passage of 6.02 x 1023 electrons can produce
a. 22.4 Litres of H2 gas (at STP) from water
b. 22.4 Litres of O2 gas (at STP) from water
c. 1 mole of Cl2 gas from HCl solution
d. 1 mole of metallic silver from AgNO3 solution
e. 1 mole of metallic copper from CuSO4 solution
212
84
29.
Po 
4
2
He + ?
The missing product in the equation above is
a.
216
86
Pb b.
216
82
Pb c.
212
82
Pb d.
208
84 Pb
e.
208
82 Pb
30. The most massive particle among the following is
a. alpha particle b. beta particle c. positron
d. neutron
Some typical required problems
31. When hydrochloric acid and zinc metal react, the gas produced is collected in an evacuated flask. After the
system has returned to room temperature (27.2oC), the pressure inside the flask is 350 mm Hg. The volume of the
flask is 255 mL. The energy released during this reaction is 152.4 kJ per mole of Zn.
a. How many moles of gas have been collected?
b. Write the chemical reaction, including the correct numerical energy term on
the appropriate side
c. Assuming that the zinc has been completely consumed, how many grams of
zinc were used in this reaction?
d. If the resulting solution was evaporated, what is the name of the solid
compound that would remain?
e. How many kJ of heat energy are released by the amounts used in this
problem?
32. Given the following reactions:
S(s) + O2(g)  SO2(g)

Ho = -297 kJ/mol
1
SO2(g) + 2 O2(g)  SO3(g)
 Ho = -141 kJ/mol
a. calculate H for the reaction: S(s) +
3
2
O2(g)  SO3(g)
b. using values in your text book, calculate So at 298 K for this reaction.
c. using your value for Ho and So, calculate Go at 298 K.
d. sketch a reaction energy diagram for the reaction, indicating where the
enthalpy quantity would be measured.
FINAL EXAM MATERIALS 8 33. The reaction
NO2(g) + CO(g)  NO(g) + CO2(g)
has been studied to determine the effect of varying the concentrations of nitrogen dioxide and carbon monoxide
upon the rate of the reaction. The rate was determined by noting changes in absorbance in the system (NO2 is
colored, all other gases are colorless).
Rate of Absorbance
decrease
(/s)
0.020
0.080
0.72
0.72
Initial Concentrations
[NO2]
[CO]
1 x 10-3
6 x 10-3
2 x 10-3
6 x 10-3
-3
6 x 10
1 x 10-3
6 x 10-3
2 x 10-3
a. write a consistent rate law expression for this reaction
b. determine the value of the rate constant, k, including its units.
c. what will the initial rate of the reaction be if each initial concentration is
2.0 x 10-3 M?
d. a possible mechanism is given below; label the SLOW step and indicate any
unstable intermediates
NO2 + NO2  NO3 + NO
NO3 + CO  NO2 + CO2
34. Write the equilibrium constant expression for the following reaction:
2 HI(g)  H2(g) + I2(g)
a. If Kc = 0.016 at 520oC, calculate the concentrations of all species at
equilibrium when 0.50 mol of HI is placed in a 5.0 L container.
b. H for this reaction is -52 kJ. How will the value of Kc change if the
temperature is increased to 700oC? Why?
Some typical problems to choose from
35. A solution contains the following salts in equal, dilute concentrations: NiF2, ZnF2, and CuF2. Using inert
electrodes, current is passed through the solution beginning with a very small voltage and gradually increasing the
voltage to 4.5 volts. Give the order in which substances will be produced (and at which electrode) as the voltage is
gradually increased.
36. What is the molar mass of glucose if 22.5 g gives a freezing point of
-0.930oC when dissolved in 250 g (to the nearest 1 g) of water? (Kf for water is 1.86oC/m)
37. The solubility product constant, Ksp, for silver bromide, AgBr, is
4.8 x 10-13. When equal volumes of 2.0 x 10-3 M AgNO3 and 2.0 x 10-3 M NaBr are mixed will a precipitate form?
38. Formic acid, HCHO2, has a Ka of 1.78 x 10-4. For a 0.45 M solution of formic acid calculate [H+], the pH,
and the % dissociation.
39. A solution containing a +3 metal ion is electrolyzed by a current of 5.00 A for 10.0 min. What is the identity of
the metal if 1.18 g of metal was plated out in this electrolysis.
40. A 10.0 mL sample of vinegar, an aqueous solution of acetic acid (CH3COOH), is titrated with 0.5062 M NaOH,
and 16.58 mL is required to reach the end point.
a. What is the Molarity of the acetic acid?
b. If the density of the vinegar is 1.006 g/mL, what is the mass % of acetic acid in vinegar?
FINAL EXAM MATERIALS 9 Some typical essay TOPICS to choose from
41. periodic properties and chemical/physical behavior
42. contrasting various types of bonds
43. buffer solutions
44. effects on reaction rate and collision theory
45. vapor pressure, structure and weak forces
46. fission and fusion
[remember, prime candidates for essay topics include those things which we have spent time describing in some
detail and which do not lend themselves to problem-solving; diagrams may be very useful in some cases]
FINAL EXAM MATERIALS 10 Answers to Sample Final Exam
1. b
2. c
3. d
4. c
5. a
6. d
7. b
8. d
9. d
10. c
11. d
12. b
13. d
14. b
15. b
16. a
17. d
18. a
19. c
20. a
21. c
22. c
23. e
24. d
25. b
26. d
27. c
28. d
29. e
30. a
31.
a. 0.00476 mol gas
b. Zn + 2 HCl ® ZnCl2 + H2 + 152.4 kJ
c. 0.312 g Zn
d. zinc choride
e. 0.726 kJ
32.
a. -438 kJ/mol
b. -83.2 J/mol·K
c. -413.2 kJ/mol
FINAL EXAM MATERIALS 11 33.
a. rate = k[NO2]2
b. k = 2.0 x 104 /M2s
c. rate = 8.0 x 10-2/s
d. NO3; first step is SLOW
34. K c =
[H 2 ][I 2 ]
[HI]2
a. [H2] = [I2] = 0.010 M, [HI] = 0.080 M
b. Kc at 700 < Kc at 520
35.
at the cathode: first Cu, then Ni, then Zn, then H2
at the anode: O2 only
this is based on the net voltage in each case; the lowest net voltage occurs first until
all of that substance is used up (or roughly, anyway…)
36. 180 g/mol
37. since Qsp = 1 x 10-6 >>> Ksp, then YES
38. [H+] = 8.9 x 10-3 M, pH = 2.05, % ionization = 2.0%
39. Indium
40.
a. 0.839 M
b. 5.01%
FINAL EXAM MATERIALS 12