General Chemistry Exam 1
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Transcript of General Chemistry Exam 1
Page 1 of 1
Printed Last Name: |___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|
Printed First Name: |___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|___|
UNI ||___|___|___|___|___|___|___|___|
School: |___|Barnard |___|College |___|Engineering |___|General Studies
Chem C1403 Exam 1 Tuesday October 4, 2012
Professor David Reichman
INSTRUCTIONS (1) You are provided with an Exam Booklet and a Bubble Sheet.
(2) Confirm that your exam booklet contains 15 pages composed of
(a) 1 cover page (i.e. this page)
(b) 6 pages of exam
(c) 3 pages of reference material (relevant constants, and Periodic Table)
(d) 5 pages of scratch paper
(3) Fill in your name and UNI where indicated at the top of this page
(4) Complete the following on the Bubble Sheet using a soft lead pencil
(a) Print your last name, first name and middle initial in the box provided; also enter this information into
the bubbles. Please note that you must fill in the “empty” bubble at the top to indicate spaces between your
names.
(b) Fill in your UNI in the space provided.
(c) Fill in the one response that best answers each question. There is only one correct answer to each
question. Any question with more than one answer marked on the bubble sheet will not be counted.
(d) Under no circumstances are you allowed to make any marks on the bubble sheet except those described
above; scratch paper is provided for this purpose
(5) You are allowed 75 minutes to complete the exam.
(6) Check the blackboard frequently for time remaining and other information.
(7) Please remain seated when you have finished the exam, until the exam booklet and bubble sheet are taken
from you by a proctor. You are not allowed to take any of this material out of the exam room, including
scratch paper.
(8) REMEMBER! It is your responsibility to ensure that your bubble sheet and exam sheets are properly identified.
OTHER INFORMATION
(1) Your score will be the total number of correct answers; therefore, it is to your advantage to answer every
question.
(2) There are 25 questions and each will be equally weighted in the grading.
Chem 1403/Reichman Exam 1 Oct 4, 2012
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1)What is the atomic symbol for an element with 29 protons and 33 neutrons?
a) 62 29Ni
b) 31 28Ni
c) 62 29Cu
d) 29 62Sm
e) 33 29Cu
2) How many of the following did Dalton not discuss in his atomic theory?
I. isotopes
II. ions
III. protons
IV. neutrons
V. electrons
a) 1
b) 2
c) 3
d) 4
e) 5
3) A collection of protons has a charge of 0.025 C. How many moles of protons are in the
container?
a) 3215.0
b) 5.2x102
c) 1.0x10-4
d) 0.003
e) 2.6x10-7
4) The mass of protons in the above container is
a) 2.6x10-10
kg
b) 0.001 kg
c) 24 kg
d) 3.0x10-9
kg
e) 1.0x10-8
kg
Chem 1403/Reichman Exam 1 Oct 4, 2012
Page 2 of 6
5) Consider the production of ammonia gas through the reaction of nitrogen with hydrogen as
described by the unbalanced equation below. How much N2 would be required to react
completely with 3.0 mol of H2?
N2(g) + H2(g) � NH3(g)
a) 14.0 g
b) 28.0 g
c) 42.0 g
d) 126 g
e) None of these is with in 5% of the correct answer
6) For a certain element, the volume of the nucleus is 1.288x10-42
m3 and the volume of the
atom is 4.34x10-29
m3 (recall Vsphere=4/3 πr
3). The ratio of the radius of an atom to the radius
of the nucleus in the atom, ratom/rnucleus is about
a) 3x103
b) 3x104
c) 3x105
d) 3x106
e) 3x107
7) The elemental percentage composition by mass of a compound may be determined if which
of the following is known?
a) The relative numbers of each kind of atom making up the compound.
b) The empirical formula of this compound.
c) The molecular formula of this compound.
d) Any one of the above will allow the percentage composition by mass to be determined.
e) None of the above will allow the percentage composition by mass to be determined.
8) Which of the following statements is/are true?
i) The number of protons is the same for all neutral atoms of an element
ii) The number of electrons is the same for all neutral atoms of an element
iii) The number of neutrons is the same for all neutral atoms of an element
a) (i), (ii), and (iii) are all true.
b) Only (i) and (ii) are true.
c) Only (ii) and (iii) are true.
d) Only (i) and (iii) are true.
e) (i), (ii), and (iii) are all false.
Chem 1403/Reichman Exam 1 Oct 4, 2012
Page 3 of 6
9) A single atom of an element weighs 3.34x10-22
g. Identify the isotope
a) 237Np
b) 35Cl
c) 103Rh
d) 201Hg
e) None of the above
10) For a new element, 67.16% is an isotope with mass 280.8 amu, 2.76% is an isotope with
mass 283.7 amu, and the rest is an isotope with mass 284.8 amu. Calculate the average
atomic mass of this new element.
a) 282.1 amu
b) 283.1 amu
c) 313.4 amu
d) 280.8 amu
e) 849.3 amu
11) How many molecules of ammonia are present in 6.1 g of ammonia (NH3)
a) 3.63x101
b) 3.63x1024
c) 3.6x10-25
d) 7.43x1023
e) 2.16x1023
12) The mass of 0.82 mol of a diatomic molecule is 85.3 g. Identify the molecule.
a) F2
b) Cl2
c) Br2
d) Cr2
e) Xe
13) A given sample of xenon fluoride contains molecules of a single type, XeFn, where n is some
whole number. Given that 9.03x1020
molecules of XeFn weigh 0.368 g, calculate n
a) 1
b) 2
c) 4
d) 6
e) None of these
Chem 1403/Reichman Exam 1 Oct 4, 2012
Page 4 of 6
14) A substance contains 3.024 g hydrogen, 30.97 g phosphorus, and 64.00 g oxygen. How
many grams of oxygen are in an 85.00-g sample of the substance?
A) 16.00 g
B) 55.51 g
C) 64.00 g
D) 130.1 g
E) none of these
15) You find a compound composed only of element X and hydrogen, and you know that it is
82.8% element X by mass. Each molecule has 2.5 times as many H atoms as X atoms. What is
element X?
a. C
b. Ne
c. Si
d. Cl
e. Cu
16) Consider the following unbalanced reaction
C4H10 + O2 � CO2 + H2O
For every 2.0 mol of C4H10, ______mol of O2 is required
a. 1.0
b. 6.5
c. 8.0
d. 13.0
e. None of these
17) When the equation C11H24 + O2 � CO2 + H2O is balanced with the smallest set of integers,
the sum of the coefficients is
a. 41
b. 44
c. 53
d. 64
e. 75
Chem 1403/Reichman Exam 1 Oct 4, 2012
Page 5 of 6
18) Calculate ∆E in kilojoules per mole for the reaction
230
90Th → 4
2He + 1
1Ra
Atomic masses: 230
90Th = 230.0332, 4
2He = 4.00260, 1
1Ra = 226.02544.
a) –4.6 × 108 kJ/mol
b) –2.4 × 106 kJ/mol
c) 0
d) +2.4 × 106 kJ/mol
e) +4.6 × 108 kJ/mol
19) Consider the following process: 14
7N + 4
2He � 17
8O + 1
1H
Masses(amu): N:14.003074 He:4.002603 O:16.999133 H:1.007825
Which statement describes ∆E for the process?
a) 1.15 x 1011
J/mol is released.
b) 1.15 x 1014
J/mol is released.
c) 1.15 x 1018
J/mol is absorbed.
d) 1.15 x 1011
J/mol is absorbed.
e) none of these
20) Consider a world in which like charges attract and opposite charges repel but otherwise
Coulomb’s form of the potential energy holds. Which of the following statements is true:
a. Bringing two electrons closer will increase their mutual potential energy.
b. Bringing an electron and a proton closer together will decrease their mutual
potential energy.
c. Bringing two electrons closer will decrease their mutual potential energy.
d. Moving two electrons further apart will decrease their mutual potential energy.
21) Determine the difference in mass between 1 mol of iron-56 nuclei and the component
nucleons of which it is made.
a) 9.41 x 10–6
kg
b) 2.43 x 10–5
kg
c) 6.65 x 10–5
kg
d) 5.27 x 10–4
kg
e) 7.21 x 10–4
kg
Chem 1403/Reichman Exam 1 Oct 4, 2012
Page 6 of 6
22) Consider the following process. Which statement describes ∆E for the process?
14
7� +
4
2� →
17
8� +
1
1�
a. 1.15x1011
J/mol is released
b. 1.15x1014
J/mol is released
c. 1.15x1018
J/mol is absorbed
d. 1.15x1011
J/mol is absorbed
e. None of the above is within 5% of the correct answer
23) Which of the following statements is true?
a. The emission spectrum of hydrogen is continuous.
b. In the photoelectric effect, the kinetic energy of released electrons is proportional
to the intensity of incident light.
c. The scattering of alpha particles by metal foil is consistent with the plumb
pudding model.
d. The double slit experiment shows that massive particles (like electrons) can have
wave-like properties and show an interference pattern.
e. Blackbody radiation can be accounted for by assuming that the matter
(atoms/electrons) inside the blackbody absorbs energy continuously.
24) If some light has a wavelength of 1.2x103 nm. What is the energy of a photon of this
light?
a. 1.10x10-19
J
b. 3.68x10-20
J
c. 2.71x1018
J
d. 1.66x10-19
J
e. 1.33x10-18
J
25) Consider an atom traveling at 5% of the speed of light. The de Broglie wavelength is
found to be 3.83x10–3
pm. Which element is this?
a. He
b. Ca
c. F
d. Li
e. P
Chem 1403/Reichman Exam 1 Oct 4, 2012
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Chem 1403/Reichman Exam 1 Oct 4, 2012
Page 2 of 3
1 femtometer = 1 fm = 1x10-15
m
1 picometer = 1 pm = 1x10-12
m
1 nanometer = 1 nm = 1x10-9
m
Formulas
E=hυ=hc/λ
λ=h/p
p=mv
Planck’s Constant: h = 6.6261x10-34
Js
Speed of Light c=2.99792458x108 m/s
Chem 1403/Reichman Exam 1 Oct 4, 2012
Page 3 of 3
Vcoulomb=Z1 Z2 e2 /(r1+r2)