Chem. 1C Midterm 1
First initial
of last name
Practice Test 1
Name__________________________________________
Perm Number ___________________________________
All work must be shown on the exam for partial credit. Points will be taken off for
incorrect or no units. Calculators are allowed. Cell phones may not be used for
calculators. On fundamental and short answer 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.
Fundamentals
(of 36 possible)
Problem 1
(of 13 possible)
Problem 2
(of 21 possible)
Multiple Choice
(of 30 possible)
Midterm Total
(of 100 possible)
1
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
A new substance developed in the laboratory has the following properties:
normal subliming point, 197.5 K; triple point, 216.6 K and 5.2 atm; critical
temperature, 304.25 K; critical pressure, 73 atm. Studies of this substance
have shown the solid phase to be more dense than the liquid phase. Sketch
the approximate phase diagram for this new substance given the data above.
Label all phases and important points.
2a) 2 pts
Iron crystallizes in a bcc structure, The atomic radius of iron is 124 pm.
Determine the number of atoms per unit cell?
2b) 4 pts
Determine the length of the sides of the unit cell?
3)
What intermolecular forces are present in:
Circle the strongest intermolecular force present in each compound
6 pts
KBr
CH3(CH2)50CH2OH
CO2
OBr2
2
4)
6 pts
Circle the formula that best fits the following description.
Highest melting point:
C7H16
C10H22
Lowest boiling point:
C3H8
(CH3)2O
Lowest viscosity:
CH3CH2SH
CH3CH2OH
Highest surface tension:
5)
6 pts
Study the following sketch of a molecular orbital (MO) in a homonuclear
diatomic molecule. This MO was formed by combining a 3p atomic orbital
for each of the atoms.
* The dark dots in this sketch
are the nuclei
What is the symbol for this MO? __________________________________
Is this a bonding or antibonding MO? ______________________________
What is the energy of this MO, compared to the energy of a 3p orbital on
one of the separate atoms? (circle one)
Higher
Lower
The Same
Not Enough Info
6)
6 pts
How are the local electron model and molecular orbital theory similar?
How are they different? (75 words or less)
3
Short Answer Questions
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)
13 pts
In Breckenridge, Colorado, the typical atmospheric pressure is 520. torr. What is
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the boiling point of water (ΔHvap=40.7೘೚೗
) in Breckenridge? What pressure would
have to be applied to steam at 350.˚C to condense the steam to liquid water?
4
2a) 7 pts
1) Identify the electronic structure of XeO3.
2) Identify the molecular structure of XeO3.
3) Identify the bond angles XeO3.
4) Identify the polarity of XeO3.
5) What method did you use to determine these answers?
2b)
7 pts
1) What is the hybridization of all of the atoms in COCl2?
2) Determine the number of σ and π bonds in COCl2?
3) What orbital(s) overlap to make the bond(s) in this molecule? If there
are any lone pair(s) of electrons what type of orbitals are they in?
4) What method did you use to determine these answers?
2c)
7 pts
1) What is the full electron configuration F2 (include core electrons)?
2) What is the bond order for F2? What does this tell you about the bond?
3) Is F2 diamagnetic or paramagnetic?
4) What method did you use to determine these answers?
5
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 forms 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. What is the vapor pressure of water (at sea level) at 100.0°C?
A) More information is needed.
B) 1 torr
C) 760 torr
D) 85 torr
E) 175 torr
2. Which of the following statements is true?
A) Antibonding MOs have electron density mainly outside the space between the two
nuclei.
B) Electrons are never found in an antibonding MO.
C) All antibonding MOs are higher in energy than the atomic orbitals of which they are
composed.
D) None of these statements is true.
E) Two of these statements are true.
3. The unit cell in this two-dimensional crystal contains __________ Xs and __________
Os.
A)
B)
C)
D)
E)
4, 1
1, 1
2, 1
1, 2
None of the above
6
4. Complete the Lewis structure for the following molecule.
CH3 O
CH3 CH C C N
This molecule has __________ sigma bonds and __________ pi bonds.
A) 6, 3
B) 13, 2
C) 4, 5
D) 11, 5
E) None of the above
5. Calculate the interplanar distance that has a second order reflection of 43.2  for x-rays
of wavelength of 0.141 nm.
A) 0.412 nm
B) 0.193 nm
C) 0.103 nm
D) 0.169 nm
E) None of the above
6. If four orbitals on one atom overlap four orbitals on a second atom, how many
molecular orbitals will form?
A) 8
B) 16
C) 4
D) 1
E) None of the above
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