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Midterm

CHM135H1 Study Guide - Midterm Guide: Uncertainty Principle, Potassium Dichromate, Atomic Orbital


Department
Chemistry
Course Code
CHM135H1
Professor
all
Study Guide
Midterm

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Multiple Choice Questions
1. Potassium dichromate, K2Cr2O7, is used in tanning leather, decorating porcelain, and water
proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K2Cr2O7.
a) 9.490 x 1025 Cr atoms
b) 2.248 x 1024 Cr atoms
c) 1.124 x 1024 Cr atoms
d) 3.227 x 1023 Cr atoms
e) 1.613 x 1023 Cr atoms
2. Atomic orbitals developed using quantum mechanics:
a) Describe regions of space in which one is most likely to find an electron.
b) Describe exact paths for electron motion.
c) Give a description of the atomic structure which is essentially the same as the Bohr
model.
d) Allow scientists to calculate an exact volume for the hydrogen atom.
e) Are in conflict with the Heisenberg Uncertainty Principle.
3. In the photoelectric effect, a photon with an energy of 5.3 x 10-19 J strikes an electron in a
metal. Of this energy, 3.6 x 10-19 J is the minimum energy required for the electron to escape
from the metal. The remaining energy appears as kinetic energy of the photoelectron. What
is the velocity of the photoelectron, assuming it was initially at rest?
a) 3.7 x 1014 m/s
b) 3.7 x 1011 m/s
c) 1.9 x 106 m/s
d) 6.1 x 105 m/s
e) 1.7 x 10-19 m/s
4. Which of the following is a correct set of quantum numbers for an electron in a 5f orbital?
a) n = 5, l = 3, ml = +1
b) n = 5, l = 2, ml = +3
c) n = 4, l = 3, ml = 0
d) n = 4, l = 2, ml = +1
e) n = 5, l = 4, ml = 3
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5. What is the correct order of decreasing size of the following ions?
a) P3- > Cl- > K+ > Ca2+
b) Ca2+ > K+ > Cl- > P3-
c) K+ > Cl- > Ca2+ > P3-
d) K+ > Cl- > P3- > Ca2+
e) None of the above is correct.
6. At very high pressures (~ 1000 atm), the measured pressure exerted by real gases is greater
than that predicted by the ideal gas equation. This is mainly because
a) Such high pressures cannot be accurately measured.
b) Real gases will condense to form liquids at 1000 atm pressure.
c) Gas phase collisions prevent molecules from colliding with the walls of the container.
d) Of attractive intermolecular forces between gas molecules.
e) The volume occupied by the gas molecules themselves becomes significant.
7. Octane has a vapor pressure of 40. Torr at 45.1°C and 400. What is its heat of vaporization?
a) 39.9 kJ/mol
b) 46.0 kJ/mol
c) 590 kJ/mol
d) 710 kJ/mol
e) None of the above
8. Select the pair of substances, assumed to be in their liquid phase, in which the one with the
higher vapor pressure at a given temperature is listed first.
a) C7H16, C5H12
b) CCl4, CBr4
c) H2O, H2S
d) CH3CH2OH, CH3-O-CH3
e) Xe, Kr
9. A certain mineral, MxMyAz, crystallizes in the cubic unit cell shown below. M and M
represent cations and A represents the anions. What is the empirical forumula of the
mineral?
a) MMA
b) MMA3
c) M2MA3
d) M8MA6
e) Cannot be determined.
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