Download CHEM 1211K Test IV MULTIPLE CHOICE. (3 points each) 1) The

CHEM 1211K
Test IV
MULTIPLE CHOICE. (3 points each)
1)
The basis of the VSEPR model of molecular bonding is __________.
A) regions of electron density on an atom will organize themselves so as to maximize s-character
B) atomic orbitals of the bonding atoms must overlap for a bond to form
C) regions of electron density in the valence shell of an atom will arrange themselves so as to
maximize overlap
D) electron domains in the valence shell of an atom will arrange themselves so as to minimize
repulsions
E) hybrid orbitals will form as necessary to, as closely as possible, achieve spherical symmetry
2)
The molecular geometry of __________ is square planar.
A) XeF4
B) XeF2
C) CCl 4
3)
4)
The molecular geometry of the PF4+ ion is __________.
A) trigonal pyramidal
C) tetrahedral
E) trigonal bipyramidal
Of the molecules below, only __________ is nonpolar.
A) PBr 3
B) BF3
C) BrCl 3
D) ICl 3
E) PH3
B) trigonal planar
D) octahedral
D) NF3
E) IF5
5)
The combination of two atomic orbitals results in the formation of __________ molecular orbitals.
A) 1
B) 2
C) 3
D) 4
E) 0
6)
The hybridization of orbitals on the central atom in a molecule is sp. The electron-domain geometry
around this central atom is ________.
A) linear
B) tetrahedral
C) trigonal bipyramidal
D) trigonal planar
E) octahedral
7)
The hybrid orbitals used for bonding by the sulfur atom in the SF 4 molecule are __________
orbitals.
A) sp
B) sp2
C) sp3
D) sp3d
E) sp3d2
8)
When three atomic orbitals are mixed to form hybrid orbitals, how many hybrid orbitals are
formed?
A) six
B) three
C) one
D) four
E) five
9)
In a typical multiple bond, the sigma bond results from overlap of __________ orbitals and the pi
bond(s) result from overlap of __________ orbitals.
A) hybrid, hybrid or atomic
B) hybrid, atomic
C) hybrid, hybrid
D) atomic, hybrid
E) hybrid or atomic, hybrid or atomic
10) Which of the following statements about gases is false?
A) All gases are colorless and odorless at room temperature.
B) Distances between molecules of gas are very large compared to bond distances within
molecules.
C) Non-reacting gas mixtures are homogeneous.
D) Gases expand spontaneously to fill the container they are placed in.
E) Bases are highly compressible.
11) Of the following, __________ is a correct statement of Boyle's law.
A) n/P = constant
B) V/P = constant
C) V/T = constant
D) P/V = constant
E) PV = constant
12) A sample of a gas (5.0 mol) at 1.0 atm is expanded at constant temperature from 10 L to 15 L. The
final pressure is __________ atm.
A) 0.67
B) 15
C) 7.5
D) 1.5
E) 3.3
13) A balloon originally had a volume of 4.39 L at 44oC and a pressure of 729 torr. The balloon must
be cooled to __________oC to reduce its volume to 3.78 L (at constant pressure).
A) 273
B) 546
C) 38
D) 0
E) 72.9
14) If 50.75 g of a gas occupies 10.0 L at STP, 129.3 g of the gas will occupy __________ L at STP.
A) 3.92
B) 25.5
C) 12.9
D) 5.08
E) 50.8
15) Which statement about ideal behavior of gases is false?
A) Volume of 2.00 moles of oxygen gas, O 2, is assumed to be the same as that of 2.00 moles of
carbon dioxide gas, CO2, as long as the temperature and pressure conditions are the same.
B) Gas ideality assumes that there are no interactions between gas particles.
C) Low pressures and high temperatures typically cause deviations from the ideal gas behavior.
D) All particles in the ideal gas behave independently of each other.
E) At low densities all gases have similar properties.
16) Standard temperature and pressure (STP), in the context of gases, refers to __________.
A) 298 K and 1 torr
B) 273 K and 1 pascal
C) 273 K and 1 atm
D) 298 K and 1 atm
E) 273 K and 1 torr
17) A vessel contained N 2, Ar, He, and Ne. The total pressure in the vessel was 987 torr. The partial
pressures of nitrogen, argon, and helium were 44, 486, and 218 torr, respectively. The partial
pressure of neon in the vessel was __________ torr.
A) 521
B) 760
C) 42.4
D) 19.4
E) 239
18) In the van der Waals equation, the constants a and b __________.
A) are equal to each other for any real gas
B) are used to correct for the difference between Celsius and Kelvin
C) are used to correct for the fact that collisions of gas molecules are not really completely elastic.
D) are equal to 1 for ideal gases
E) are used to correct for the finite volume of gas molecules and the attractive forces between gas
molecules.
19) The strongest interparticle attractions exist between particles of a __________ and the weakest
interparticle attractions exist between particles of a __________.
A) solid, liquid B) liquid, solid
C) liquid, gas
D) solid, gas
E) gas, solid
20) When NaCl dissolves in water, aqueous Na + and Cl - ions result. The force of attraction that exists
between Na + and H2O is called a(n) __________ interaction.
A) ion-ion
B) London dispersion force
C) ion-dipole
D) hydrogen bonding
E) dipole-dipole
21) Elemental iodine (I2) is a solid at room temperature. What is the major attractive force that exists
among different I2 molecules in the solid?
A) London dispersion forces
B) ionic-dipole interactions
C) dipole-dipole attractions
D) dipole-dipole rejections
E) covalent-ionic interactions
22) The heat of fusion of water is 6.01 kJ/mol. The heat capacity of liquid water is 75.2 J/mol(K) the
conversion of 50.0 g of ice at 0.00oC to liquid water at 22.0oC requires __________ kJ of heat.
A) 0.469
B) 3.8 x 10 2
C) 21.3
D) 17.2
E) Insufficient data
23) On the phase diagram below, segment __________ corresponds to the conditions of temperature
and pressure under which the solid and the gas of the substance are in equilibrium.
A) CD
B) BC
C) AC
24) Which of the following is not a type of solid?
A) ionic
C) metallic
E) supercritical
D) AB
E) AD
B) covalent-network
D) molecular
25) Crystalline solids differ from amorphous solids in that crystalline solids have __________.
A) a long-range repeating pattern of atoms, molecules, or ions
B) no orderly structure
C) much larger atoms, molecules, or ions
D) atoms, molecules, or ions that are close together
E) appreciable intermolecular attractive forces
Problems
1. (5 points) What type of intermolecular forces between the following liquid substances:
Br2
London forces
H2O
Hydrogen bonding
CH3CH 2CH2CH 3
London forces
2. (10 points) Give the shape and hybridization for the following molecules:
molecule
shape
hybridization
H3O+
trigonal pyramid
sp3
SCN-
linear
sp
BF3
trigonal planar
sp2
BeH2
linear
sp
CO2
linear
sp
3. (10 points) Ammonium sulfate, an important fertilizer, can be prepared by the reaction of ammonia
with sulfuric acid:
2 NH 3(g) + H2SO4(aq) à (NH4) 2SO 4(aq)
Calculate the volume of NH 3(g) needed at 42oC and 15.6 atm to react with 87kg of H 2SO 4.
temp. in kelvin = 42 o C + 274
= 315 K
87,000 g
moles sulfuric acid =
98 g / mol
= 887 .6moles
2 NH 3
x
=
1 H 2 SO 4 887 .6 moles
x = 1775 moles NH 3
PV = nRT
(15 .6atm )(V ) = (1775 mol )( 0.08206 )( 315 K )
(1775 mol )( 0 .08206 )( 315 K )
15. 6atm
= 2941 .1L or 2 .94 ×10 3 L
V=