chem k e y iii on pages recitation section grading parts
TRANSCRIPT
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_______K E Y _____________ 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).
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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
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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: ______C__________
Question 3. (5 pts.) Which equation correctly represents the electron affinity of phosphorus?
Answer: ______A__________
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)
Chem 177 Spring 2012 Exam 3
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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? ____________________B
Question 7. (5 pts.) Which compound would most likely have non‐polar covalent bonds? _A
Question 8. (5 pts.) Which compound would most likely have polar covalent bonds, but no overall dipole moment? ______________________________________D
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
Chem 177 Spring 2012 Exam 3
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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
Chem 177 Spring 2012 Exam 3
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: ___________[Ar] 3d5 ________________________________
Question 17. Complete and balance the following reactions; include phases.
(a) (5 pts.) _2_ K (s) + _2_H2O(l) → __2 KOH(aq) + H2(g)_____
(b) (5 pts.) _1_CO2(g) + _1 or 2 __NaOH(aq) → _NaHCO3(aq) or Na2CO3(aq) + H2O(l)
(c) (5 pts.) _1_Na2O (s) + _1_H2SO4(aq) → __Na2SO4(aq) + H2O(l)__
(d) (4 pts.) _2_Li(s) + _1_S(s) → ____Li2S(s)________________________
Chem 177 Spring 2012 Exam 3
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: ________120°___________ (c) (3 pts.). Estimate the H‐C‐H bond angle: _______109.5°___________ (d) (3 pts.). What is the hybridization of the carbon atom that is attached to the oxygen
atoms?________(sp2) (p) or sp2 ____________________
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
number of bonds broken 1 2 number of bonds formed 1 2 2
ΔHrxn= [(839 + 2×299) – (348 + 2 × 240 + 2 × 413)] kJ = ‐217 kJ
Answer: ____ ΔHrxn= -217 kJ _____
Chem 177 Spring 2012 Exam 3
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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 produce __________.
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