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Name_____________________________________________Per______Date_________
Honors Chemistry Midterm Exam
Thursday, January 19, 2012
7:20 am
Room ___________
The exam consists of 2 major sections: multiple choice and free response. Note the
following important points as you prepare for the exam:
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You will be provided a reference booklet, exam, and opscan sheet for
multiple choice answers.
You will not be permitted to bring additional reference materials to the test
room.
You will need to bring YOUR OWN CALCULATOR and pencil.
You will not be permitted to share or borrow calculators during the exam
period.
The attached review packet is meant to assist you in preparing for your exam. However,
you should ALSO study concepts and problems from your class notes and chapter
assignments. The review packet is intended to be a supplement.
The multiple choice section of the exam is 35 questions with each question being worth 1
point. The free response section is worth 65 points. The following is a list of the
possible problem/question topics for the free-response section.
Density
Unit Conversions
Percent Error and percent yield
Percent Composition
Empirical/molecular formula
Predicting products for chemical reactions (naming/formula writing)
Balancing equations and identifying reaction types
Net ionic equations and identifying precipitates
Molarity problems
Stoichiometry (including mass, volume, representative particles, molarity etc.)
Limiting and excess reactant problems
Identifying oxidation and reduction reactions and assigning of oxidation numbers
Wavelength, frequency and energy problems
Electron Configurations of all types (full, abbreviated and orbital diagram)
Scenarios with a reading section and multiple choice, problem solving, and short answer questions based on
the scenario
Also, you should review the names of common lab equipment and glassware and procedures.
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1. Introduction
A. Identify each of the following as either a physical or chemical change.
1.
2.
3.
4.
Wax melting.
Iron rusting.
Hydrogen and oxygen combining together to form water.
Distillation (boiling) of water.
B. Identify each of the following as either a physical or chemical property.
1.
2.
3.
4.
5.
Color
Reactivity with oxygen
Solubility in water
Density
If the substance is an acid or a base
C. Identify each of the following as either an extensive or intensive property.
1.
2.
3.
4.
Volume
Boiling Point
Mass
Density
D. Distinguish between precision and accuracy.
E. How is percent error calculated?
2. Metric Conversions and Density
A. A solid object with a mass of 22.50 g and a density of 4.50 g/mL is placed in a
graduated cylinder with 30.6 mL of water in it. When the object is completely submerged
in the water, what will the new volume reading in the cylinder be?
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B. How many mm are there in 2.95 x 106 km?
C. How many cubic cm are there in 10.8 cubic decameters?
D. The density of potassium dichromate is 2.68 g/cm3. Express this number in pounds
per cubic foot. ( 1.00 lb = 454.0 g and 1.00 in = 2.54 cm)
3. Chemical laws
A. Law of conservation of mass
B. Law of multiple proportions
C. Law of constant composition (definite composition)
For each of the following statements, consider which law above best applies to it. Then,
write the letter of the law next to its number.
1. All water is exactly 11.11% hydrogen by mass.
2. In the reaction between hydrogen and oxygen, exactly 2.02 g of H2 react with
exactly 32.00 g of O2 to form 34.02 g of H2O.
3. In one compound, 6.00 g of carbon combines with 8.00 g of oxygen. In a
second compound, 6.00 g of carbon combines with 16.00 g of oxygen.
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4. Atomic Structure
A. In one atom of uranium-235,
there are _________protons, ___________neutrons and ____________electrons.
B. Given an ion of sulfur-34:
1. Write the symbol:
2. List the number of protons_______, neutrons________ and electrons.
C. List the contributions (experiments and conclusions) of each of the following
scientists who helped develop current atomic theory.
1. J.J. Thomson
2. Millikan
3. Rutherford
4. Bohr
5. Lavoisier
6. Mendeleev
D. Define isotope.
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E. Explain how the atomic masses on the periodic table are calculated from the
naturally occurring isotopes.
5. Formulas, mole conversions and molarity
A. Write the formula for each of the following, and classify each as ionic or
covalent.
1. aluminum sulfate
2. sulfur trioxide
3. copper (II) hydroxide
4. iron (III) phosphate
B. Define the mole.
C. Distinguish between a strong, weak and non-electrolyte.
D. Calculate the following quantities.
1. How many nitrate ions in 2.50 moles of aluminum nitrate?
2. How many moles of CO2 are there in a 450. g sample of CO2?
3. What is the mass of 8.00 x 1024 formula units of NaCl?
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4. How many grams of aluminum nitrate are needed to make 350. mL of a 1.45
M solution?
5. If 2.00 g of sodium sulfate are dissolved in 20.0 mL of solution, what is
a. the molarity of the solution?
b. the molarity of the sodium ions?
6. What is the percent by mass of hydrogen in ammonium phosphate?
7. When oxygen is bubbled through a solution of sodium polysulfide, a
compound used in photography called “hypo” is produced. What is the empirical
formula of hypo if it consists of 29.08% sodium, 40.57% sulfur, and the
remainder is oxygen?
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8. The empirical formula of a compound is C2H3. What is the molecular formula
of this compound if the molar mass is 135 g/mole?
6. Equations and stoichiometry
A. First, write a balanced chemical equation for each reaction. Next, classify each
reaction(synthesis, decomposition, single replacement, double replacement).
1. nitrogen gas and magnesium metal react to form solid magnesium nitride.
Balanced chemical equation:
Type: ___________________
2. Aqueous silver nitrate and nickel metal react to form silver metal + aqueous
nickel (III) nitrate.
Type:____________________________
3. Solid Platinum (IV) fluoride reacts to form platinum metal and fluorine gas
Type: ___________________
4. When a solution of sodium sulfate is added to a solution of iron (III) nitrate, a
precipitate forms.
a. Write the complete balanced equation for the reaction.
b. Identify the precipitate: ________________________
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c. Identify the type of reaction: ___________________
d. Identify the spectator ion(s):_____________________
e. Write the net ionic equation:
B. Redox Equations
1. Identify the oxidation numbers in each of the following:
C2O4 -2
NaClO
NH4+1
2. What are the defining characteristics of each of the following types of equations?
Oxidation –
Reduction –
3.
Given the following UNBALANCED equation:
C3H8 (g) +
O2 (g)

CO2 (g)
+
H2O (l)
a. If you react 2.00 g of C3H8 with 8.00 g of O2, what mass of water is
formed?
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b. If 2.25 g of water is produced experimentally, what is the % yield?
4. Ammonia, NH3, is used to make fertilizers for lawns and gardens by reacting
nitrogen gas with hydrogen gas.
a. Write a balanced equation with the smallest whole-number coefficients for
this reaction.
b. How many moles of ammonia are formed when 1.34 moles of nitrogen
react?
c. How many grams of hydrogen are required to produce 2.75x103 g of
ammonia?
7. Light and Electron Configuration
A. State the relationship between frequency, wavelength and the speed of light.
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B. Determine the number of:
1. electrons occupying the p orbitals in the arsenic atom?
2. orbitals in the third energy level?
3. d orbitals in a d sublevel?
4. valence electrons in an atom of sulfur?
C. Define the term isoelectronic.
D. What ion with a charge of -2 is isoelectronic with an argon atom?
E. Write both the complete and the abbreviated (short-hand or core) electron
configuration of:
1. an aluminum atom
2. a sulfide ion
3. an atom of uranium
F. Draw an orbital diagram (orbital configuration or notation) of the following. DO NOT
use abbreviated (short-hand) notation.
1. a phosphorus atom
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2. a strontium ion
H. Distinguish between ground and excited state for an atom.
I. The laser in a CD player uses light with a wavelength of 780 nm. Calculate the energy
of this radiation, in joules per photon.
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10.Science Scenario Question
Directions: Read the following article. Using the article, answer the questions on the
next page.
Let us examine and interpret an investigation as it might have appeared in an article,
“Global Warming?” The Chickadees Don’t Mind.” Printed in a magazine called
Feathered Friends Digest. (Note: Both the magazine title and the article are fictitious.)
Bird enthusiasts in Anytown, Pennsylvania, have recently completed a study of the effect
of climate change on the chickadee population. The chickadee is a small, seed-eating
songbird, common in the Northeastern United States through out the year.
The study compares the mean (average) June and December temperatures, as reported by
the National Weather Service, with the number of chickadees counted by the Audubon
Society during its December and June bird counts. The Audubon Society is a recognized
group of bird experts that conducts nationwide bird counts around June 21 and December
21 each year.
The table below lists the number of chickadees counted in Anytown during the two
annual counts each year, and the mean temperature during the month preceding the count
that year.
During the 10 year period of the study, there has been a 3.9ºC in crease in the mean June
temperature, from 23.3 ºC to 27.2 ºC. In that time, the summer count of chickadees
increased almost 70 percent, from 89 to 147 birds. The man December temperature
increased 2.7 ºC, from 1.7 ºC to 4.4 ºC, with an increase in the winter count of chickadees
of nearly 75 percent.
We conclude that whatever harm global warming may do to the environment, it does not
endanger the chickadee population. In fact, as the climate continues to become warmer,
we can look forward to ever-increasing numbers of these delightful songbirds.
Year
1997
1998
1999
2000
2001
2001
2003
2004
2005
2006
Mean temperature
in June ºC
23.3
23.9
22.2
24.4
24.4
25
26.1
26.7
26.7
27.2
Number of chickadees
found in summer
89
91
92
95
94
110
122
134
146
147
Mean temperature in
December ºC
1.7
1.7
0.6
1.7
2.8
2.8
3.9
3.3
5.6
4.4
Number of chickadees
found in winter count
95
98
101
102
102
120
133
145
160
162
Now, let us analyze the article and the validity of its conclusions. Should we assume that
the data are accurate? Since both the National Weather Service and The Audubon
Society are reliable and impartial sources, we believe the data to be accurate.
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However, we must question the validity of the conclusion. This conclusion was not
based on a controlled experiment. There may have been other reasons for the change in
the chickadee population. In addition, the sample size was very small considering the
large number of chickadees that can be found throughout the United States. If we were to
graph this data, we would notice that in 2002 there was a sudden large increase in the bird
population without a corresponding jump in temperature. A good scientific analysis of
this data must include an explanation of all the observations, not just those that support
one particular explanation.
Questions
1. What hypothesis did the author of this article propose?
2. Which of the following conclusions is not supported by the data?
A. More chickadees are seen in December that in June
B. Over the 10-year period, the mean June temperature has generally
increased.
C. Over the 10-year period, the chickadee population has generally increased.
D. Global warming is causing an increase in the bird population.
Base your answers to questions 3 and 4 on the following article, “Seed Sales
Level Off,” which appeared the following month in Feathered Friends Digest.
(Note: As before, both the magazine and the title of the article are fictitious.)
The Munchies Seed Company, which specializes in distributing seed for
songbirds to homeowners in Pennsylvania, has reported that after the enormous
growth in sales that began in 2002, sales for the year 2007 are slightly below last
year’s levels. Company officials go on to state that they knew that the enormous
growth in the number of people actively feeding songbirds could not go on
indefinitely.
3. What alternative explanation for the increase in the chickadee population is
provided by the data in this second article?
4. The mean temperature in Anytown, Pennsylvania, in June 2007 was 27.8 ºC.
Predict the (approximate) number of chickadees that will be counted by the
Audubon Society during the summer count; justify your prediction.