Chem. 1C Final Practice Test 2 - UC Santa Barbara

7) Use the following reaction diagram to answer the following questionsName__________________________________________
Perm Number __________________________________
All work must be shown on the exam for partial credit. Points will be taken off for incorrect or
missing units. Calculators are allowed. Cell phones may not be used for calculators. On
fundamental and challenge problems you must show your work in order to receive credit for the
problem. If your cell phone goes off during the exam you will have your exam removed
from you.
First letter
2
Fundamental Questions Each of these fundamental chemistry questions is worth 6 points. You must show work to get
credit. Little to no partial credit will be rewarded. Make sure to include the correct units on your
answers.
1) 6 pts Consider the structure of mimosine shown below.
What functional groups are present? Circle the functional groups present in
mimosine.
secondary amine ketone primary amine ester
2) 6 pts [Fe(H2O)6] 3+ absorbs light =700. nm. What is the value (in
) of Δo and
=
(2.83 × 10−19


700 nm is in the red region of the spectrum. Therefore, the complex is
green.
3) 6 pts Draw or name each of the following:
5-methyl-2-hexyne
Br
3
4) 6 pts Draw all of the structural isomers for C6H14. Circle those that can be
geometric isomers.
None of these can be geometric isomer. You must have a double bond to
have geometric isomers
5) 6 pts
Which has the lowest melting point: C3H8 CH3OH
Which has the greatest surface tension: N2(l) Br2(l)
At room temperature each of the following organic molecules has a different
phase. Match the molecule to the phase.
Hexane Solid
Propane Liquid
Dodecane Gas
6a) 4 pts A new substance developed in a laboratory has the following properties:
normal melting 83.7C; normal boiling point, 177C; triple point 200. torr
and 38.6C. Sketch the approximate phase diagram and label the solid,
liquid, and gaseous phases.
6b) 2 pts Based on your drawing is the solid or liquid more dense?
Solid is more dense because when you increase pressure you transition
from liquid to solid.
4
7) 6 pts A freshly isolated sample of 90Y was found to have an activity of
9.8×105 disintegrations per minute at 1:00 pm on December 3, 2000. At
2:15 pm on December 17, 2000, its activity was redetermined and found to
be 2.6×104 disintegrations per minute. Calculate the half-life of 90Y.
() = − + () Determine t:
Amount of time between readings
14 full days + 1 hour + 15 minutes
Convert to min:
14 (24
1 ) + 15 = 20,235
(2.6 × 104) = −(20,235 ) + (9.8 × 105)
= 1.79 × 10−4 1

= 3,864 = 2.7
8) 5 pts The following data was collected for the reaction
A + B C + D Ea=161

What is k at 40.0°C?
( 2
) = 161,000

9) 6 pts What is the freezing point of 2.0 g of CaCl2 dissolved in 1.0 L of water?
2 = 1.0
110.984 2 ) = 0.018 2
= 1.0 ( 1000
1 ) (
1
) = 0.100
10) 6 pts Calculate the binding energy per nucleon (
) for 62Ni
(62 = 61.928 )
1 28 62
Δm = 62 − (281
Convert mass to kg
−0.5862 ( 1.6605×10−27
1 ) = −9.760 × 10−28
)

11a) 3 pts The carbon-14 nuclide radioactively decays by beta emission. Write a
balanced nuclear chemical equation that describes this process.
6 14 → −1
0 + 7 14
11b) 3 pts The tungsten-180 nuclide radioactively decays by alpha emission. Write a
balanced nuclear chemical equation that describes this process.
74 180 → 2
4 + 72 176
12) 5 pts Determine the rate law from the following mechanism.
H2S H+ + HS- fast equilibrium
Cl2 + HS- H+ + 2Cl- + S slow
Indicate if the reaction contains intermediates or catalysts and which
substances they are.
Rate= k2[Cl2][HS-]
[−] = 1
−1
[+]
6
Challenge Problems Each of the following short answer questions are worth the noted points. Partial credit will be
given. You must show your work to get credit. Make sure to include proper units on your
answer.
1) 18 pts A mixture of NaCl and sucrose (C12H22O11) of combined mass 10.2 g is
dissolved in enough water to make up a 250.0 ml solution. The osmotic
pressure of the solution is 7.32 atm at 23C. Calculate the mass present of
NaCl in the mixture.
+ 122211 = 10.2
Looking for mass % NaCl
Π =
)(296.15)
0.25
When the NaCl dissolves the = + = − therefore our expression can
simplify to
0.075 = 2
7
2a) 8 pts Arsine, AsH3, is a highly toxic compound used in electronic industry for
the production of semiconductors. Its vapor pressure is 35 torr at
-111.95C and 253 torr at -83.6C. Using this date calculate the standard
enthalpy of vaporization.


2b) 8 pts What is the normal boiling point of arsine?
At the boiling point Pvap = atmospheric pressure = 1 atm=760 torr
( 760
8
3) 10 pts A positron and an electron annihilate each other upon colliding, thereby
producing energy:
−1 0 + 1
0 → 2 0 0
Assuming that both γ rays have the same energy, calculate the wavelength
of the electromagnetic radiation produced.
Calculate the Δm (electron and positron weights are the same)
= 0 − 2(9.10939 × 10−31 ) = −1.82188 × 10−30
Calculate the energy
)
2
= −1.63742 × 10−13 Therefore the energy released per photon is
1.63742×10−13
Calculate the wavelength of the photons
=
=
=
)
= 2.42631 × 10−3
9
4a) 8 pts Teflon is made from the monomer tetrafluoroethene. Draw the structure for
tetrafluoroethene and the repeating unit for Teflon.
F F
Tetrafluoroethylene Teflon (repeating unit)
4b) 4 pts Is the synthesis of Teflon an example of addition polymerization or
condensation polymerization?
Addition
4c) 8 pts Draw the structure for the tripeptide, Val-Ala-Cys, in that order.
4d) 4 pts The analysis of a protein for its amino acid content is valuable in
determining the protein's… (circle one)
Primary Structure Secondary Structure Tertiary Structure
10
Multiple Choice Questions Each of the following multiple choice questions are worth 5 points. Your
answers need to be filled in on your ParSCORE form. Note: Your
ParSCORE will not be returned to you, therefore, for your records, you
may want to mark your answers on this sheet. On the ParSCORE you
need to fill in your perm number, test version, and name. Failure to do
any of these things will result in the loss of 1 point. Your perm number
is placed and bubbled in under the “ID number.” Do not skip boxes or put
in a hyphen. In addition, leave bubbles blank under any unused boxes.
The version number (A) is bubbled in under the “test form.”
1. Which of the following is paramagnetic?
A) [Co(NH3)6] 3+ (strong field)
B) [Fe(CN)6] 4- (strong field)
C) [Mn(en)3] 2+ (strong field)
D) [Zn(H2O)6] 2+
The U-238 nucleus decays to form Pb-206 by and decays.
2. Calculate the number of decays.
A) 4
B) 8
C) 2
D) 6
A) aldehydes.
B) ketones.
C) ethers.
A) the temperature.
E) none of these
11
5. One of the hopes for solving the world's energy problem is to make use of the fusion
reaction
2
1 H + 3
1 H 4
2 He + 1
0 n + energy
How much energy is released when 1 mol of deuterium is fused with 1 mol of tritium
according to the above reaction? The masses of the atoms and the neutrons are as
follows: 2
1 H = 3.01605 amu
0 n = 1.008665 amu
A) 7.84 1044 J
B) 5.63 108 J
D) 1.69 1012 J
E) none of these
6. Using the data below, calculate the vapor pressure of chloroform over a chloroform-
benzene solution at 25°C, which contains 50.0 g of CHCl3 and 50.0 g of C6H6. Assume
that the solution behaves ideally.
Vapor pressure at 25°C
benzene (C6H6) 94.4 torr
chloroform (CHCl3) 172.0 torr
E) none of these
7. The unit cell in a certain lattice consists of a cube formed by an anion at each corner, an
anion in the center, and a cation at the center of each face. The unit cell contains a net
A) 2 anions and 3 cations.
B) 5 anions and 6 cations.
C) 3 anions and 4 cations.
D) 5 anions and 3 cations.
E) none of these
12
8. If a tree dies and the trunk remains undisturbed for 13,750 years, what percentage of the
original 14C is still present? (The half-life of 14C is 5730 years.)
A) 45.0%
B) 5.20%
C) 19.0%
D) 2.20%
A)
B)
C)
D)
E) none of these
10. The most likely decay mode (or modes) of the unstable nuclide 11
6 C would be
E) electron capture.
11. For the reaction 2A+B products determine the value of K given the following data:
Exp [A]o (M) [B]o (M) Initial Rate (
)
A) 0.29
B) 0.63
C) 1.3
D) 2.0
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12. A solution of two liquids, A and B, shows negative deviation from Raoult's law. This
means that
A) molecules of A interact weakly, if at all, with B molecules.
B) molecules of A interact more strongly with B than with A or and more strongly than
B with B.
C) the two liquids have a positive heat of solution.
D) molecules of A interact strongly with other A-type molecules.