General Chemistry Exam 1

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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.

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General Chemistry

Transcript of General Chemistry Exam 1

Page 1: General Chemistry Exam 1

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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.

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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

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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.

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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

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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

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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

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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

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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

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Vcoulomb=Z1 Z2 e2 /(r1+r2)