Dr. Kathy Burke CHEM III TA on pages Recitation Section ... · CHEM 177 Evening Exam III ... To receive full credit on problems, ... legibly, include units, and report your answer

Dr. Kathy Burke Dr. Irmi Schewe‐Miller This exam consists of 19 + 4 questions on 6 pages

CHEM 177 Evening Exam IIIApril 15, 2013

Name____________________________ Recitation TA_____________________ Recitation Section_________________

Grading

Parts Points Score NOTE: To receive full credit on problems, you must clearly show all work and your method of determining the answer must be clear. The final answer must be reported to the correct number of significant figures and have the correct units. Questions are written on both sides of each page. The last page contains useful information and a periodic table; the last page should be removed and used for scratch paper and as a reference. Do not put answers on the tear away page.

Part A: 15 questions: 75

Part B: 4 questions:

page 6 23

page 7 22

Subtotal part B 45

Part C: (4 EC) 12

TOTAL 120 (+12 ) pts

Name Recitation Sections Exam location

Umesh Chaudhary 13,14 Gilman 1002

Adam Feenstra 10 Gilman 1002

Margarita Geraskina 9, 5 Gilman 1002

Jason Goh 19 Gilman 1352

Madhur Joshi 16,18 Gilman 1352

Shalika Khindurangala 7 Lebaron 1210

Nitin Kumar 2,20 Gilman 1652

Chia‐Cheng, Lin 15,17 Lebaron 1210

Amanda Nguy 21 MacKay 0117 Balcony

Vy Nguyen 1,4 Lebaron 1210

Regina Reinig 3,6 Lebaron 1210

Sweta Vangaveti 8,11 MacKay 0117 Main

Sagarika Weerasekara 22,12 MacKay 0117 Main

Important information for the rest of this semester:

Optional exam: April 29, 6:45 to 7:45 pm. The optional exam can replace a missed exam or an exam with an unusually low score. The optional exam is cumulative, all multiple choice questions, and machine graded (same rooms as previous exams). Please use Blackboard to indicate which exam you wish to replace, no later than April 22 at 7 pm.

Final exam: May 9, 7 – 9 pm. The final exam is worth 150 points; it is cumulative, all multiple choice questions, and machine graded (same rooms as previous exams).

page 2

Please read the following instructions carefully before proceeding! Part A of your exam will be computer graded. In order for the computer to identify who you are, it is important that you complete the information section properly.

You must use a #2 pencil and completely fill in the appropriate circles on the computer scan sheet. 1. 2.

3.

To help you code the correct circles, first write your last name, first name and middle initial in the boxes (skip a space between each). Then darken the circles that match the letters in the box above it. See the sample to the right. Write the middle nine digits of your ISU identification number in the boxes A‐I. Do not skip any spaces. Below each number, darken the circle that matches this number. For example, 123456789. See the sample at bottom right.

Write your recitation section number in the special code area, boxes K‐L. Do not skip any spaces. For example, if you are in section 8, write 08. Again, darken the circle that matches the number above it. See the sample at bottom far right.

Parts A & C: Select the one best answer for each question. Place your answer on the computer answer sheet by darkening the proper circle for that question. Your computer scan sheet will be your official answer sheet for Parts A & C. Circle the answer on these sheets for your own reference.

Part B: For full credit, show all your work legibly, include units, and report your answer to the correct number of significant figures.

All material (exam, answer sheet, scratch paper) must be returned to your TA in order for us to grade your exam.

Chem 177 Spring 2012 Exam 3

page 3

Part A: Multiple Choice: (15 questions at 5 pts. each) Select the one best answer for each question. Place your answer on the computer answer sheet by darkening the proper circle for that question. Your computer scan sheet will be your official answer sheet for Parts A and C. Circle the answer on this sheet for your own reference.

Question 1. (5 pts.) The atomic radius generally increases as we move __________.

A) up a group and from left to right across a period B) up a group and from right to left across a period C) down a group and from left to right across a period D) down a group and from right to left across a period E) down a group; the period position has no effect

Use the following possible answers for the next two questions:

A) P (g) + e‐ → P‐ (g)

B) P (g) → P‐ (g) + e‐

C) P (g) → P+ (g) + e‐

D) P‐ (g) → P (g) + e‐

E) P+ (g) + e‐ → P (g)

Question 2. (5 pts.) Which equation correctly represents the first ionization of phosphorus?

Answer: ________________

Question 3. (5 pts.) Which equation correctly represents the electron affinity of phosphorus?

Answer: ________________

Question 4. (5 pts.) Which of the following is an isoelectronic series?

A) B5‐, Si4‐, As3‐, Te2‐

B) F‐, Cl‐, Br‐, I‐ C) S, Cl, Ar, K

D) Si2‐, P2‐, S2‐, Cl2‐

E) O2‐, F‐, Ne, Na+

Question 5. (5 pts.) Predict the products of this reaction: Cl2 (g) + H2O (l) → __________

A) HCl (aq) + HOCl (aq)

B) 2 Cl- (aq) + H2O (l)

C) 2 HCl (aq) + O2 (g)

D) 2 HCl (aq) + O2- (g)

E) Cl2 (aq) + H2O (l)


page 4

Use the following possible answers for the next three questions: A) PH3(g)

B) CaCl2(s)

C) CHCl3()

D) BCl3(g)

Question 6. (5 pts.) Which compound would most likely be ionic? ______________________

Question 7. (5 pts.) Which compound would most likely have non‐polar covalent bonds? ___

Question 8. (5 pts.) Which compound would most likely have polar covalent bonds, but no overall dipole moment?________________________________________

Question 9. (5 pts.) Lattice energy is __________.

A) the energy required to produce one mole of an ionic compound from its constituent elements in their standard states

B) the energy required to convert a mole of ionic solid into its constituent ions in the gas phase

C) the energy given off when gaseous ions combine to form one mole of an ionic solid D) the sum of ionization energies of the components in an ionic solid E) the sum of electron affinities of the components in an ionic solid

For the next two questions, consider the covalent compound arsine, AsH3. Arsine has the following Lewis structure:

Question 10. (5 pts.) The central atom in arsine has ___ bonding pair(s) of electrons and ___ lone pair(s) of electrons.

A) one, one B) one, three C) zero, one D) three, one E) three, two

Question 11. (5 pts.) The electron domain geometry of arsine is ______ and the molecular geometry is ____.

A) trigonal planar, trigonal planar B) tetrahedral, trigonal pyramidal C) trigonal planar, bent D) trigonal bipyramidal, see‐saw E) square planar, T‐shaped

As HH

H


page 5

Question 12. (5 pts.) ClF3 has "T‐shaped" geometry. There are __________ non‐bonding

domains in this molecule.

A) 0 B) 1 C) 2 D) 3 E) 4

Question 13. (5 pts.) According to valence bond theory, which orbitals overlap in the formation of the bond in HBr?

A) 1s on H and 4p on Br B) 1s on H and 4s on Br C) 1s on H and 3p on Br D) 2s on H and 4p on Br E) 2s on H and 3p on Br

Question 14. (5 pts.)The π bond in ethylene, H2C=CH2, results from the overlap of

__________.

A) sp3 hybrid orbitals B) s atomic orbitals C) sp hybrid orbitals

D) sp2 hybrid orbitals E) p atomic orbitals

Question 15. (5 pts.) Using electronegativity values from the information page, decide which covalent bond would be the most polar.

A) C‐H B) C‐N C) C‐F D) O‐H E) Cl‐F


page 6 total points this page ____

Part B: For full credit, show all your work legibly on the exam paper, include units, and report your answer to the correct number of significant figures. No work shown = 0 points.

Question 16. (4 pts.) Write the condensed electron configuration of a Mn2+ ion

Answer: _________________________________________________________

Question 17. Complete and balance the following reactions; include phases.

(a) (5 pts.) ___K (s) + ___H2O(l) → ____________________________

(b) (5 pts.) ___CO2(g) + ___NaOH(aq) → ____________________________

(c) (5 pts.) ___Na2O (s) + ___H2SO4(aq) → ____________________________

(d) (4 pts.) ___Li(s) + ___S(s) → ____________________________


total points this page ____ page 7

Question 18.

(a) (5 pts.) Complete ONE of the contributing resonance structures for the acetate ION, CH3COO

− . The skeleton is shown below (three H’s attached to first C, first C attached to second C, second C attached to O’s); mark all multiple bonds, lone pairs, and formal charges.

H O

H C C O

H

(b) (3 pts.). Estimate the O‐C‐O bond angle: __________________________ (c) (3 pts.). Estimate the H‐C‐H bond angle: __________________________ (d) (3 pts.). What is the hybridization of the carbon atom that is attached to the oxygen

atoms?____________________________

Question 19. (8 pts) Using the table of average bond energies below, calculate the H for the reaction in units of kJ.

H H | | H—C C—H (g) + 2 H—I (g) —> I—C—C—I (g) | | H H

Bond C C C—C H—I C—I C—H

Bond energy, kJ/mole 839 348 299 240 413

Answer: _____________________________


page 8

Part C: Extra credit Questions (3 pts. ea)

Select the one best answer for each question. Place your answer on the computer answer sheet by darkening the proper circle for that question. (There will be open spaces for questions 16 to 19.) Your computer scan sheet will be your official answer sheet for Parts A and C. Circle the answer on this sheet for your own reference.

Question 20. Ozone is a (an) __________ of oxygen.

A) isotope B) allotrope C) precursor D) peroxide E) free radical

Question 21. Xenon has been shown to form compounds only when it is combined with __________.

A) something with a tremendous ability to remove electrons from other substances B) another noble gas C) something with a tremendous ability to donate electrons to other substances D) an alkali metal E) an alkaline earth metal

Question 22. Which nonmetal exists as a diatomic solid?

A) bromine B) antimony C) phosphorus D) iodine E) boron

Question 23. The reaction of alkali metals with oxygen produces __________.

A) oxides B) peroxides C) superoxides D) all of the above E) none of the above

Information:

You may remove this page and use it for scratch paper. Do not put any answers on this page.

NA=1 mol = 6.022 1023 particles/mol

all elements

FW of compound (number of atoms)(atomic weight) ΔHrxn ≈ Σ(bond enthalpies of bonds broken) – Σ(bond enthalpies of bonds formed)

μ = Q ∙r Eel = (κ∙Q1∙Q2)/d

1 D = 3.34 × 10‐30 C∙m ; D = (debye); C∙m = (coulomb‐meters)

e = 1.6 × 10‐19 C (coulombs)

Scale Conversions: 1 L = 1000 mL = 1000 cm31 pm = 1010 cm

1Å = 10−10 m 1 nm = 109 m 1 kJ = 1000 J

Pe rio d ic Ta b le o f t he Ele m e n t s

1 0 3Lr

( 2 6 0 )

1 0 2No

( 2 5 9 )

1 0 1Md

( 2 5 8 )

1 0 0Fm

( 2 5 7 )

9 9Es

( 2 5 2 )

9 8Cf

( 2 5 1 )

9 7Bk

( 2 4 7 )

9 6Cm

( 2 4 7 )

9 5Am

( 2 4 3 )

9 4Pu

( 2 4 4 )

9 3Np

( 2 3 7 )

9 2U

2 3 8

9 1Pa

2 3 1

9 0Th

2 3 2

7 1Lu

1 7 5

7 0Yb

1 7 3

6 9Tm1 6 9

6 8Er

1 6 7

6 7Ho

1 6 5

6 6Dy

1 6 2

6 5Tb

1 5 9

6 4Gd

1 5 7

6 3Eu

1 5 2

6 2Sm

1 5 0

6 1Pm

( 1 4 5 )

6 0Nd

1 4 4

5 9Pr

1 4 1

5 8Ce

1 4 0

8 A1 8

7 A1 7

6 A1 6

5 A1 5

4 A1 4

3 A1 3

La n t h a n id e s

Ac t in id e s

1 0 9Mt

( 2 6 6 )

1 0 8Hs

( 2 6 5 )

1 0 7Bh

( 2 6 2 )

1 0 6Sg

( 2 6 3 )

1 0 5Db

( 2 6 2 )

1 0 4Rf

( 2 6 1 )

8 9Ac

2 2 7

8 8Ra

2 2 6

8 7Fr

( 2 2 3 )

8 3Bi

2 0 9

8 2Pb

2 0 7

8 1Tl

2 0 4

8 0Hg

2 0 1

7 9Au

1 9 7

7 8Pt

1 9 5

7 7Ir

1 9 2

7 6Os

1 9 0

7 5Re

1 8 6

7 4W

1 8 4

7 3Ta

1 8 1

7 2Hf

1 7 8

5 7La

1 3 9

5 6Ba

1 3 7

5 5Cs

1 3 3

5 1Sb

1 2 2

5 0Sn

1 1 9

4 9In

1 1 5

4 8Cd

1 1 2

4 7Ag

1 0 8

4 6Pd

1 0 6

4 5Rh

1 0 3

4 4Ru

1 0 1

4 3Tc

( 9 8 )

4 2Mo

9 5 .9

4 1Nb

9 2 .9

4 0Zr

9 1 .2

3 9Y

8 8 .9

3 8Sr

8 7 .6

3 7Rb

8 5 .5

8 6Rn

( 2 2 2 )

8 5At

( 2 1 0 )

8 4Po

( 2 0 9 )

5 2Te

1 2 8

5 3I

1 2 7

5 4Xe

1 3 1

3 6Kr

8 3 .8

3 5Br

7 9 .9

3 4Se

7 9 .0

3 3As

7 4 .9

3 2Ge

7 2 .6

3 1Ga

6 9 .7

3 0Zn

6 5 .4

2 9Cu

6 3 .5

2 8Ni

5 8 .7

2 7Co

5 8 .9

2 6Fe

5 5 .8

2 5Mn

5 4 .9

2 4Cr

5 2 .0

2 3V

5 0 .9

2 2Ti

4 7 .9

2 1Sc

4 5 .0

2 0Ca

4 0 .1

1 9K

3 9 .1

1 8Ar

3 9 .9

1 7Cl

3 5 .5

1 6S

3 2 .1

1 5P

3 1 .0

1 4Si

2 8 .1

1 3Al

2 7 .0

2He

4 .0 0

1 0Ne

2 0 .2

9F

1 9 .0

8O

1 6 .0

7N

1 4 .0

6C

1 2 .0

5B

1 0 .88 B

2 B1 2

1 B1 11 098

7 B7

6 B6

5 B5

4 B4

3 B3

1 2Mg

2 4 .3

1 1Na

2 3 .0

4Be

9 .0 1

3Li

6 .9 4

2 A2

1 A1

1H

1 .0 1

1 1 0Ds

( 2 8 1 )

Fig. 7.11 First Ionization energies for the Elements

Fig. 7.14 Electron Affinities

H 2.1

Li 1.0

Be1.5

B 2.0

C 2.5

N 3.0

O 3.5

F 4.0

Na0.9

Mg1.2

Al 1.5

Si 1.8

P 2.1

S 2.5

Cl 3.0

K 0.8

Ca 1.0

Ga 1.6

Ge 1.8

As 2.0

Se 2.4

Br 2.8

Rb0.8

Sr 1.0

In 1.7

Sn 1.8

Sb1.9

Te2.1

I 2.5

Cs 0.7

Ba 0.9

Pb 1.9

Bi 1.9

Fig. 7.7 Trends in atomic radii

Electronegativities for main group elements

based on Pauling’s thermochemical data

EN bond characteristic ≥ 1.8 mostly ionic 1.7 50% ionic, 50% covalent 0.5 - 1.6 mostly polar covalent 0.0 - 0.4 mostly covalent

Dr. Kathy Burke CHEM III TA on pages Recitation Section ... · CHEM 177 Evening Exam III ... To receive full credit on problems, ... legibly, include units, and report your answer

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