1. Draw the Lewis Structure for PCl5.
a. What shape is this molecule? Trigonal bipyramidal
b. What are the bond angles? 120, 90
2. Draw three possible Lewis Structures for SO3 and indicate which is the most accurate.
Why is this?
c. What shape is this molecule? Trigonal planar
d. What are the bond angles? 120
3. The work function for tungsten (W) is φW = 4.52 eV.
What is the maximum kinetic energy, Kmax, of emitted electrons when light of
wavelength λ = 200 nm is used to irradiate a piece of W?
If the energy of the photon is greater than the work function, hc/λ > φ, then the
extra energy goes into kinetic energy of the photoelectrons. In this case, we have
Kmax = hc/λ − φW = 1240/200 − 4.52 = 1.68 eV.
4. A decrease in temperature and an increase in pressure.
5. Using the experimental apparatus shown in
Figure 27.5, when ultraviolet light with a wavelength
of 240 nm shines on a particular metal plate,
electrons are emitted from plate 1, crossing the gap
to plate 2 and causing a current to flow through the
wire connecting the two plates. The battery voltage
is gradually increased until the current in the
ammeter drops to zero, at which point the battery
voltage is 1.40 V.
(a) What is the energy of the photons in the beam of light, in eV?
(b) What is the maximum kinetic energy of the emitted electrons, in eV?
(c) What is the work function of the metal, in eV?
(d) What is the longest wavelength that would cause electrons to be emitted, for this
particular metal?
(e) Is this wavelength in the visible spectrum? If not, in what part of the spectrum is this
light found?
6. State in your own words the Pauli exclusion principle and Hund’s rule.
e. Pauli exclusion principle: If 2 electrons occupy the same orbital, they must have
opposite spins.
f. Hunds rule: If more than one orbital is available, add electrons with parallel spins
to the orbitals first before pairing up electrons.
7. Which ground state elements correspond to the following electron configurations?
g. [Rn] 5f146d37s2 Dubnium
h. [Ne] 3s23p4 Sulfur
i.
[Xe] 4f145d66s2 Osmium
8. Write the ground state electron configuration of Chromium in orbital notation.
9. Dry ice is carbon dioxide in the solid state. 1.28 grams of dry ice is placed in a 5.00 L
chamber that is maintained at 35.1oC. What is the pressure in the chamber after all of
the dry ice has sublimed?
10. Two flasks are connected with a stopcock. Flask #1 has a volume of 2.5 L and
contains oxygen gas at a pressure of 0.70 atm. Flask #2 has a volume of 3.8 L and
contains hydrogen gas at a pressure of 1.25 atm. When the stopcock between the two
flasks is opened and the gases are allowed to mix, what will the resulting pressure of the
gas mixture be?
11.
12. EXAMPLE PROBLEM: Predicting Thermal Equilibrium Temperatures A 12.00-g block of
copper at 12.0 ºC is immersed in a 5.00-g pool of ethanol with a temperature of 68.0 ºC. When
thermal equilibrium is reached, what is the temperature of the copper and ethanol?
13. The following information is given for ethanol at 1 atm:
boiling point = 78.40 ºC
Hvap (78.40 ºC) = 837.0 J/g
melting point = –114.5 ºC
Hfus(–114.5 ºC) = 109.0 J/g
specific heat (gas) = 1.430 J/g·ºC
specific heat (liquid) = 2.460 J/g·ºC
A 33.50-g sample of liquid ethanol is initially at 13.50 ºC. If the sample is heated at
constant pressure (P = 1 atm.), calculate the amount of energy needed to raise the
temperature of the sample to 94.50 ºC.
14. State the number of possible electrons described by the following quantum
numbers:
a. n = 3, l = 0 2
b. b. n = 3, l = 1 6
c. c. n = 3, l = 2, ml = -1 2
d. d. n = 5, l = 0, ml -2, ms -1/2 Not possible
15. Fill in the blanks with the correct response:
a. The number of orbitals with the quantum numbers n=3, l=2 and ml = 0 is ___1___.
b. The subshell with the quantum numbers n=4, l=2 is ___d__.
c. The ml values for a d orbital are ___-2, -1, 0 , 1, 2_____.
d. The allowed values of l for the shell with n=2 are ____0, 1___.
e. The allowed values of l for the shell with n=4 are ___0, 1, 2, 3___.
f. The number of orbitals in a shell with n=3 is __1+3+5=9_(s, p, d)__.
g. The number of orbitals with n=3 and l=1 is __3____.
h. The maximum number of electrons with n=3 and l=2 is __10__.
i. When n=2, l can be __0, 1__.
j. When n=2, the possible values for ml are __-1, 0, 1____.
k. The number of electrons with n=4, l=1 is __6__.
l. The subshell with n=3 and l=1 is designated as the __p or -1, 0, 1___ subshell.
m. The lowest value of n for which a d subshell can occur is n=___3__.
16. Find the ΔH for the reaction below, given the following reactions and subsequent ΔH
values:
HCl(g) + NaNO2(s) → HNO2(l) + NaCl(s)
2NaCl(s) + H2O(l) → 2HCl(g) + Na2O(s)
NO(g) + NO2(g) + Na2O(s) → 2NaNO2(s)
NO(g) + NO2(g) → N2O(g) + O2(g)
2HNO2(l) → N2O(g) + O2(g) + H 2O(l)
Answer = -78 kJ
ΔH = 507 kJ
ΔH = -427 kJ
ΔH = -43 kJ
ΔH = 34 kJ