CHEM 111
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Name
Please circle your discussion section:
8:30 am
204
Nord 400
Allison
205
Nord 204
Casey
206
KHS 119
Priya
10:00 am
200
Ford
Alan
201
Strosacker
Franci
202
White 324
Hannah
203
NOA290
Marta
1:00 pm
207
Geller 001
Joey
208
Sears 315
Parv
209
Strosacker
Renee
210
Bingham 204
Sophia
2:30
211
Sears 439
Ketan
212
Nord 212
Naveen
213
Olin 314
Yvonne
Correct discussion section
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CHEM 111
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Network ID
Name
Please write a capital letter of the best response for each question (1-7) in each box. For questions 8-11,
place any final answers in boxes provided and be sure to use appropriate units and significant figures.
1
2
3
4
5
6
7
1. As part of the calibration of a new laboratory balance, a 1.000-g mass is weighed with the following
results:
Trial
Mass (g)
1
1.201 ± 0.001
2
1.202 ± 0.001
3
1.200 ± 0.001
The balance is:
A)
B)
C)
D)
E)
Both accurate and precise.
Accurate but imprecise.
Precise but inaccurate.
Both inaccurate and imprecise.
Accuracy and precision are impossible to determine with the available information.
2. You measure water in two containers: a 10-mL graduated cylinder with marks at every mL, and a 1-mL
pipet marked at every 0.1 mL. If you have some water in each of the containers and add them
together, to what decimal place could you report the total volume of water?
A)
0.01 mL
B)
0.1 mL
C)
1 mL
D)
10 mL
E)
none of these
3. Which of the following statements is false?
A)
Solutions are always homogeneous mixtures.
B)
The terms “atom” and “element” can have different meanings.
C)
Elements can exist as atoms or molecules.
D)
Compounds can exist as atoms or molecules.
E)
At least two of the above statements (A-D) are false.
4. You are given a compound with the formula MCl2, in which M is a metal. You are told that the metal
ion when in this compound has 25 electrons. What is the identity of the metal?
A)
Mn
B)
Al
C)
Cu
D)
Fe
E)
Co
5. Naturally occurring copper exists in two isotopic forms: 63Cu and 65Cu. The atomic mass of copper is
63.55 amu. Which isotope has the greater abundance?
63
Cu
A)
65
Cu
B)
63.55
Cu
C)
D)
the abundance of each isotope is very close to 50%
E)
we cannot tell from the information provided
CHEM 111
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6. Which of the following name(s) is(are) correct?
1. oxide, O22. ammonium nitrate, NH4NO3
3. hydrofluoric acid, HF(aq)
4. barium oxide, BaO
A)
all
B) none
C) 1, 2
D) 3, 4
E) 1, 3, 4
7. Gravimetric analysis is a technique to find quantitative information about a system using
A) Mass
B) Volume
C) Products of a combustion reaction
D) partial pressure
C) two of the above are correct
8. Fill in the following table. The symbol should match gallium in format.
69
Symbol
Ga3+
Number of protons
34
Number of neutrons
46
Number of electrons
Atomic number
Mass number
Net charge
2–
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b) Making isotopically pure samples can be very difficult and costly. Suppose a scientist was able to
produce a sample of gallium hydroxide from isotopically pure samples of 69Ga3+, 18O2-, and 2H+. What is
the chemical formula of gallium hydroxide? Gallium hydroxide is sometimes called gallium(III) hydroxide.
c) If gallium hydroxide could be measured as a fragment in a mass spec, how many peaks would you
expect to see from the sample prepared in part (b) and what would the relative abundances be?
/2
/4
d) If the scientist can sell this compound for $5,750 per mole, how much money could be earned by selling
a sample that contains 1.75x1025 protons? (Final answer should be written in box.)
$$:
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CHEM 111
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9a) Iron is biologically important in the transport of oxygen by red blood cells from the lungs to the
various organs of the body. In the blood of an adult human, there are approximately 2.69 x 1013 red blood
cells with a total of 2.90 g of iron. On the average, how many iron atoms are present in each red blood
cell? (molar mass Fe = 55.85 g/mol)
Fe atoms:
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56
57
58
b) Naturally occurring iron contains 54
26 Fe , 26 Fe , 26 Fe , and 26 Fe . The respective atomic masses are
53.940 amu, 55.935 amu, 56.935 amu, and 57.933 amu. Two of your friends are arguing about the
calculation of the average atomic mass. Friend A calculates the average mass by summing the mass of
each isotope and dividing by 4 to determine an average mass of 56.185 amu but the result does not
match the value found in the periodic table. Friend B says this is because he used the wrong number of
sig. figs in the calculation because 4 has only a single sig. fig.
i) Explain why friend B is incorrect about the number of sig. figs. in the 4 value (no more than 2 complete
sentences).
ii) Explain why friend A is incorrect in their calculation of the average mass of iron (no more than 2
complete sentences).
c) Fe(s) has a density of 4.84 g/cm3. If we manufacture a cube containing 1 mole of Fe, what are the
dimensions of this cube?
cube dimensions:
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CHEM 111
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10) Nitrogen gas (N2(g)) can reaction with hydrogen gas (H2(g)) to produce hydrazine (N2H4(l)). Write a
balanced reaction for this process.
b) What is the mass of hydrazine (N2H4) produced when 20.06 g of nitrogen reacts with 3.35 g of
hydrogen?
/4
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c) What amount of excess reagent is left over after the reaction is complete?
/6
d) A published percent yield for this reaction is 77.5%. You perform the reaction described in part (b) and
obtain 10.2 g of hydrazine (N2H4). What does this result say about your chemistry skills? Explain briefly.
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CHEM 111
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11a) A compound contains only C, H, and S. Combustion of 3.50 g of the compound produces 8.47 g
carbon dioxide, 1.44 g water and some unmeasured quantity of sulfur dioxide. What is the empirical
formula of the compound (written in the box)?
H2O: 18.015 g/mol
C: 12.011 g/mol
Helpful MM:
CO2: 44.01 g/mol
H: 1.0079 g/mol
S: 32.065 g/mol
EF:
b) If the molar mass of the compound is close to 220 g mol-1. Determine the molecular formula.
MF:
c) Assuming the products of the reaction are carbon dioxide, water and sulfur dioxide, write a balanced
combustion reaction for this compound (assume water is a liquid, the unknown is a solid, and all other
species are gases). If you could not solve part (a), use C2H8S4.
Question Score
Out of
1-7
/14
8
/24
9
/20
10
/20
11
/22
Total
100
d) Determine the mass of SO2(g) (64.1 g mol ) produced from the
combustion of 3.50 g of the compound in part (a). If you could not
solve part (a), use C2H8S4.
-1
/8
/4
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mass SO2(g):
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Name
CHEM 111
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Constants and equations:
Speed of light: c = 2.997x108ms-1
1 J = 1 kg∙m2∙s-2
mass of e-: me=9.11x10-31 kg
𝐸𝐸 = ℎ ∙ 𝜈𝜈
ℎ
ℎ
=
𝑚𝑚∙v
𝑝𝑝
𝑍𝑍2
𝑍𝑍2
−18
10 𝐽𝐽 ∙ �𝑛𝑛2 − 𝑛𝑛2 �
𝑓𝑓
𝑖𝑖
F18
Name
Plank’s constant: h=6.626x10-34 J∙s
charge of an e-: e = 1.602x10-19 C
mass of p+: mp=1.67x10-27 kg
Avogadro’s constant: NA = 6.022x1023 mol-1
𝑍𝑍 2
DeBroglie Relation: 𝜆𝜆 =
𝐸𝐸 = −2.18 × 10−18 𝐽𝐽 ∙ �𝑛𝑛2 �
PV=nRT
𝑢𝑢𝑟𝑟𝑟𝑟𝑟𝑟 = �
∆𝐸𝐸 = −2.18 ×
𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸 𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅 𝐺𝐺𝐺𝐺𝐺𝐺 1
�𝑀𝑀𝑀𝑀2
=
𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸𝐸 𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅 𝐺𝐺𝐺𝐺𝑠𝑠 2
�𝑀𝑀𝑀𝑀1
𝐿𝐿∙𝑎𝑎𝑎𝑎𝑎𝑎
𝐽𝐽
𝑅𝑅 = 0.08206
= 8.31451
𝑚𝑚𝑚𝑚𝑚𝑚∙𝐾𝐾
𝑚𝑚𝑚𝑚𝑚𝑚∙𝐾𝐾
−
c=λ∙ν
3𝑅𝑅𝑅𝑅
𝑀𝑀
𝑛𝑛 2
�𝑃𝑃 + 𝑎𝑎 � � � (𝑉𝑉 − 𝑛𝑛𝑛𝑛) = 𝑛𝑛𝑛𝑛𝑛𝑛
𝐾𝐾𝐾𝐾 =
𝑉𝑉
1
𝑚𝑚u2
2
3
= 𝑅𝑅𝑅𝑅
2
𝐴𝐴
𝐻𝐻𝐻𝐻
𝑝𝑝𝑝𝑝 = 𝑝𝑝𝐾𝐾𝑎𝑎 + 𝑙𝑙𝑙𝑙𝑙𝑙 � �
𝑝𝑝𝑝𝑝𝑝𝑝 = 𝑝𝑝𝐾𝐾𝑏𝑏 + 𝑙𝑙𝑙𝑙𝑙𝑙 � − �
𝐻𝐻𝐻𝐻
𝐴𝐴
Colligative properties: Π=iCRT
T=iKfpm
ΔT=iKbpm
PA=PAoXA
Henry’s Law: C=kP
Arrhenius equation: k=Ae-Ea/RT and A=pz
2nd order rate law: 1/[A]= kt + 1/[A]0
1st order rate law: ln[A] = -kt +ln[A]0
st
1 Law of Thermodynamics: ΔEtotal = ΔEsys+ ΔEsur =0
2nd Law of Thermodynamics: ∆Stotal = ∆Ssys+ ∆Ssur ≥ 0 and ∆Ssur = ∆Esur/T and ∆Swt = 0
3rd Law of Thermodynamics: Sº0K = 0 for pure, crystalline substances
Nernst Equation:E=Eo-(0.0592V mol e-/n)logQ
∆G=∆H-T∆S
∆rG = ∆rG° + RTlnQ
F = 96,500 C/mol e∆G=-nFE
∆rG°=-RTlnK
Score