CHEM 200/202 Fall 2015
CHEM _______
Exam 2-C
October 16, 2015
Lab Section Number: _____
Name (printed):_____________________________________________
Signature:______________________________________
This exam consists of 36 questions all of equal value for a total of 225 points.
Make sure that your test has all of the pages. Please read each problem
carefully. There are no intentionally misleading questions; each problem
should be taken at its face value. Please mark your answers on the Scantron
sheet provided to you and on the actual exam.
You will be given a periodic table and an exam information sheet to use
during the exam. You may remove it from the exam make it more accessible.
You may also use the designated Casio fx-300ms-plus calculator or
equivalent non-programmable non-graphing scientific calculator during the
exam. Use the back pages of the test as scratch paper. You are not allowed to
use any devices capable of accessing the internet, textbooks, notes, or
homemade reference sheets during the exam.
You may leave if you finish the exam early. Give the exam and the
information sheet to your TA and leave quietly without disturbing other
students. Before leaving, check that all your answers have been properly
entered on the Scantron sheet and the exam and that your name is written on
every page of the exam and on the Scantron sheet.
All cell phones and electronic devices must be turned off and put away.
Please remove all hats and caps. Place your books and all papers out of sight
under your seat. If the TA believes that you might be looking at your
neighbor’s paper, you will be asked to move to a new location.
Exam scores will be posted on Blackboard as soon as the grading is
complete. Your test will be returned to you in the first lab meeting of next
week. If you have any questions regarding the grading of your exam, please
notify your TA.
The time available for the exam is 120 minutes. Good luck!
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CHEM 200/202 Fall 2015
Exam 2-C
Name: ___________________________________________
October 16, 2015
Lab Section #: _______
Please mark your answers on the scantron sheet using a #2 pencil and also mark your answers
on the exam itself.
Mark the test from version on your scantron.
1. The most recent WiFi protocol, 802.11ac, operates at a frequency of 5280. MHz, older
protocols operated at lower frequencies (~2000 MHz). What is the wavelength of the
radiation being emitted by the new (802.11ac) WiFi devices?
(a)
(b)
(c)
(d)
(e)
56.82 mm
56.82 m
56.82 km
1.760×10−2 m
24.65 cm
2. Quantum theory attempts to resolve the wave-particle duality, where particles can act like
waves and waves can act like particles. Which example below demonstrates a wave acting
like a particle?
(a)
(b)
(c)
(d)
(e)
The photoelectric effect.
The wave motion of electrons.
Radio transmissions.
The diffraction pattern of electrons passed through a metal crystal.
The wavelengths of photons.
3. Which atomic orbital is described by the image to the right?
(a)
(b)
(c)
(d)
(e)
1p
1s
2s
3s
4d
4. Which quantum number is used to describe the direction of spin for an electron orbiting an
atom?
(a)
(b)
(c)
(d)
(e)
ml
ms
p
s
n
5. In an explanation for the quantized energy levels of atoms de Broglie theorized that orbiting
electrons might be at a fixed distance from the nucleus and thus only certain wavelengths of
wavelike motion would be stable. What is the implication of de Broglie’s theory on the
movement of matter?
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CHEM 200/202 Fall 2015
(a)
(b)
(c)
(d)
(e)
Exam 2-C
October 16, 2015
Matter does not behave as though it moves in a wave.
All matter behaves as though it moves in a wave.
Only very fast moving matter behaves as though it moves in a wave.
Only very low mass matter behaves as though it moves in a wave.
Only very high matter behaves as though it moves in a wave.
6. Blu-ray DVDs are read with a laser that has a wavelength of 405 nm. Calculate the energy
of one mole of photons from this type of laser. (a)
(b)
(c)
(d)
(e)
345 kJ
2.96×105 J
3.38×10−6 J
4.91×10−19 J
4.73×104 J
7. Which one of the following equations represents the formation reaction of ethanol
CH3CH2OH(l)? (a)
(b)
(c)
(d)
(e)
2C(g) + 2H2(g) + ½O2(g) → CH3CH2OH(l)
2C(g) + 6H(g) + O(g) → CH3CH2OH(l)
2C(graphite) + 6H(g) + O(g) → CH3CH2OH(l)
2C(diamond) + 6H(g) + O(g) → CH3CH2OH(l)
2C(graphite) + 3H2(g) + ½O2(g) → CH3CH2OH(l)
8. Calculate the ∆Hrxn for the decomposition of calcium carbonate to calcium oxide and carbon
dioxide: CaCO3(s) → CaO(s) + CO2(g) ∆H°f (kJ/mol)
(a)
(b)
(c)
(d)
(e)
CaCO3(s)
CaO(s)
CO2(s)
CO2(g)
-1206.9
-635.1
-427.4
-393.5
-2235.5 kJ
-1448.5 kJ
-178.3 kJ
178.3 kJ
2235.5 kJ
9. A system that undergoes an adiabatic change (i.e., q = 0) and does work on the
surroundings has: (a)
(b)
(c)
(d)
(e)
w < 0, ∆E < 0
w > 0, ∆E > 0
w > 0, ∆E < 0
w < 0, ∆E > 0
w > ∆E
10. Based on the Heisenberg uncertainty principle, what is the lowest possible mass for an
object who’s position could be known to ±341×10−12 m, and who’s velocity is 5.85×105 m/s
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(±1.25%)?
(a)
(b)
(c)
(d)
(e)
1.23×10−22 kg
3.82×10−29 kg
2.11×10−29 kg
2.64×10−31 kg
1.23×10−20 kg
11. For a single electron atom (i.e. hydrogen) the energy levels of all the orbitals depend on
which quantum number(s)?
(a)
(b)
(c)
(d)
(e)
The n quantum number.
The l quantum number.
The ml quantum number.
Both the n and l quantum numbers.
Both the l and ml quantum numbers.
12. Which quantum numbers below could correctly describe the orbital to
the right?
(a)
(b)
(c)
(d)
(e)
n = 1, l = 0, ml = 0
n = 2, l = 2, ml = 1
n = 3, l = 1, ml = -1
n = 3, l = 2, ml = -3
n = 3, l = 2, ml = 2
13. A system initially has an internal energy E of 501 J. It undergoes a
process during which it releases 111 J of heat energy to the
surroundings, and does work of 222 J. What is the final energy of the
system, in J? (a)
(b)
(c)
(d)
(e)
168 J
390 J
612 J
834 J
This cannot be calculated without more information
14. In which of the following processes is ∆H = ∆E ? (a) Two moles of ammonia gas are cooled from 325°C to 300°C at 1.2 atm.
(b) One gram of water is vaporized at 100°C and 1 atm.
(c) A mole of nitrogen gas reacts with a mole of oxygen gas to form two moles of
nitric oxide gas in a 40 L container.
(d) Calcium carbonate is heated to form calcium oxide and carbon dioxide in a container
with variable volume.
(e) One mole of solid carbon dioxide sublimes to the gas phase.
15. A 1.00 g piece of copper metal is initially at 100.0°C. It is dropped into a coffee cup
calorimeter containing 50.0 g of water at a temperature of 20.0°C. After stirring, the final
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temperature of both copper and water is 25.0°C. Assuming no heat losses, and that the
specific heat (capacity) of water is 4.18 J/(g•K), what is the heat capacity of the copper in J/
K? (a)
(b)
(c)
(d)
(e)
2.79 J/K
3.33 J/K
13.9 J/K
209 J/K
None of these choices is correct.
16. A common lab experiment is known as an acid-base neutralization. Typically, one may
perform the following experiment: 50.0 mL of 0.500 M HBr at 25.0°C is added to 50.0 mL of
0.500 M KOH at 25.0°C in a coffee cup calorimeter; and observe the temperature of the
mixture rises to 28.2°C. What is the heat of reaction per mole of acid? Assume the mixture
has a specific heat capacity of 4.18 J/(g•K) and the densities of the reactant solutions are
both 1.00 g/mL. (a)
(b)
(c)
(d)
(e)
670 J/mol
300 J/mol
27.8 kJ/mol
53.5 kJ/mol
> 100 kJ/mol
17. A Li2+ ion had its electron in an excited state. When the electron relaxed to the ground state
(n = 1) a photon of light was emitted with an energy of 1.884×10−17 J. What energy level
was the electron in before it transitioned to the ground state?
(a)
(b)
(c)
(d)
(e)
Emissions cannot be calculated for anything other than hydrogen atoms.
n=5
n=4
n=3
n=2
18. The International Space Station (ISS) is 400 km above the Earth’s surface, has a total mass
of 419,455 kg, and is traveling at a speed of 28,000 km/h. What is the wavelength of the
ISS as it orbits the earth?
(a)
(b)
(c)
(d)
(e)
2.0×10−43 m
3.6×10−43 m
9.4×10−46 m
1.9×10−40 m
3.4×10−44 m
19. Which atom is described by the following condensed electron configuration notation:
[Ar]4s23d2
(a) Zirconium
(b) Calcium
(c) Silicon
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(d) Chromium
(e) Titanium
20. Which of the atoms listed below has a total of only four valence electrons?
(a)
(b)
(c)
(d)
(e)
Beryllium
Carbon
Nitrogen
Oxygen
Fluorine
21. What factor best explains the reduction in the effective nuclear charge (Zeff) experienced by
the outermost electrons of a multi-electron atom?
(a)
(b)
(c)
(d)
(e)
Orbital splitting by the increased nuclear charge.
The outermost electrons are moving too quickly to feel the full pull of the nucleus.
Hund’s rule.
The inner electrons shield the outer electrons from the nuclear charge.
Pauli’s exclusion principle.
22. The partial orbital diagram below (where n could be any valid quantum number) describes
the valence electrons for which of the atoms below?
(a)
(b)
(c)
(d)
(e)
Nitrogen
Silicon
Bromine
Sulfur
Gallium
23. Platinum, which is widely used in electronics, medicine, and as a catalyst, has a work
function (the minimum energy needed to eject an electron from the metal surface) of
9.05×10−19 J. What is the longest wavelength of light that will cause electrons to be
emitted? (a)
(b)
(c)
(d)
(e)
2.20×10−7 m
4.55×10−6 m
5.65×102 m
1.37×1015 m
106 m
24. Line spectra from all regions of the electromagnetic spectrum, including the Paschen series
of infrared lines for hydrogen, are used by astronomers to identify elements present in the
atmospheres of stars. Calculate the wavelength of the photon emitted when the hydrogen
atom undergoes a transition from n = 5 to n = 3.
(a) 205.1 nm
(b) 384.6 nm
(c) 683.8 nm
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(d) 1282 nm
(e) > 1500 nm
25. Use Hess's Law to calculate the enthalpy change for recovering tungsten from its oxide
using the reaction:
WO3(s) + 3H2(g) → W(s) + 3H2O(g)
from the following data:
2W(s) + 3O2(g) → 2WO3(s), ∆H = -1685.4 kJ
2H2(g) + O2(g) → 2H2O(g), ∆H = -477.84 kJ
(a)
(b)
(c)
(d)
(e)
125.9 kJ
252.9 kJ
364.9 kJ
1207.6 kJ
None of these choices is correct.
26. You have measured the energy of a photon that you captured in a specialized detector, and
found that the photon had an energy of 6.89×10−24 J. Based on the scale below, what type
of photon was detected?
(a)
(b)
(c)
(d)
(e)
Gamma(!) ray
X ray
Ultraviolet (UV)/Visible
Infrared (IR)
Microwave
27. The dissolution of calcium hydroxide (reaction below) in water is an exothermic process.
Using the energy diagram below, identify the location of the reactants and the products on
the diagram to properly reflect the change in energy for the reaction..
Ca(OH)2(s) + H2O(l) → Ca2+(aq) + 2OH−(aq) + H2O(l)
(a)
(b)
(c)
(d)
(e)
Reactants at (1); Products at (2)
Reactants at (3); Products at (1)
Reactants at (4); Products at (3)
Reactants at (2); Products at (4)
None of these represent the energy change for this
reaction.
28. For chemists, what is the utility of the Schrödinger
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equation?
(a)
(b)
(c)
(d)
(e)
It gives us the uncertainty in either the velocity or position of an object.
It allows us to calculate the wavelength of any moving particle.
It provides the exact position of an electron.
It provides a description of where an electron may be found around a nucleus.
It scares away the non-science majors.
29. Which of the following atoms has the larger atomic radius?
(a)
(b)
(c)
(d)
(e)
Beryllium
Potassium
Phosphorus
Aluminum
Magnesium
30. Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam).
Its specific heat capacity is 1.74 J/(g•K). If 16.7 kJ of energy is absorbed by a 280. g sample
of benzene at 23.0°C, what is its final temperature? (a)
(b)
(c)
(d)
(e)
-22.3°C
36.3°C
45.3°C
57.3°C
None of these choices is correct.
31. Aluminum is made by thermally decomposing bauxite (Al2O3) into its constituent elements,
based on the reaction below. How much energy is required to produce 100.0 grams of
aluminum?
Al2O3(s) → 2Al(s) + 3⁄2O2(g) ∆Hrxn = 1676 J
(a)
(b)
(c)
(d)
(e)
16.76 kJ
1676 J
5861 J
4370 J
3106 J
32. Which of the ions listed below would be the smallest?
(a) Cl−
(b) S2−
(c) K+
(d) Ca2+
(e) They will all be the same size.
33. An electron, with a mass of 9.11×10−28 g is orbiting the nucleus of a hydrogen atom. A
measurement determines the position of the electron to within ±1.63 nm. The velocity of the
electron is measured as 6.39×106 m/s. What is the uncertainty in the velocity of the
electron?
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CHEM 200/202 Fall 2015
(a)
(b)
(c)
(d)
(e)
Exam 2-C
October 16, 2015
35.5 m/s
227 m/s
There is no uncertainty in the velocity.
4.76×104 m/s
3.55×104 m/s
34. Why does the 2s orbital fill with electrons before the 2p orbital for a multi-electron atom?
(a) Because the electronic repulsion of the protons in the nucleus impact the p orbitals
most.
(b) Because the 2s orbital penetrates closer to the nucleus than the 2p orbital.
(c) Because the s orbitals require fewer electrons to be filled.
(d) Because the p orbitals are bigger in volume than the s orbitals.
(e) Because there are more protons attracting the electrons in the s orbitals.
35. Fluorine can gain an electron to become fluoride (F−). What is the quantum number
(following the numbering conventions) that describes the electron that was gained by
fluorine.
(a)
(b)
(c)
(d)
(e)
n = 2, l = 0, ml = 1, ms = -½
n = 2, l = 1, ml = 0, ms = -½
n = 3, l = 1, ml = 1, ms = +½
n = 2, l = 1, ml = 1, ms = -½
n = 2, l = 1, ml = -1, ms = -½
36. Which of the atoms will have the smallest first ionization energy?
(a)
(b)
(c)
(d)
(e)
Helium
Strontium
Barium
Nitrogen
Fluorine
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