CHEM 1211K
Test III
MULTIPLE CHOICE (3 points each)
1) ∆H for the reaction
IF5(g) + Æ IF3(g) + F2(g)
is ________ kJ, give the data below.
IF(g) + F2(g) Æ IF3(g)
∆H = -390 kJ
IF(g) + 2 F2(g) Æ IF5(g)
∆H = -745 kJ
A) +355
B) -1135
C) +1135
D) +35
2)
A sample of aluminum metal absorbs 9.86 J of heat, upon which the temperature of the sample
increases from 23.2oC to 30.5oC. Since the specific heat capacity of aluminum is 0.90 J/g-K, the
mass of the sample is ______ g.
A) 72
B) 1.5
C) 65
D) 8.1
3)
Which of the following is a statement of Hess's law?
A) If a reaction is carried out in a series of steps, the ∆H for the reaction will equal the sum of
the enthalpy changes for the individual steps.
B) If a reaction is carried out in a series of steps, the ∆H for the reaction will equal the product of
the enthalpy changes for the individual steps.
C) The ∆H for a process in the forward direction is equal in magnitude and opposite in sign to the
∆H for the process in the reverse direction.
D) The ∆H for a process in the forward direction is equal to the ∆H for the process in the reverse
direction.
4)
Given the data in the table below, ∆Hrxn for the reaction
Ca(OH)2 + 2 H3AsO4 Æ Ca(H2AsO4)2 + 2 H2O
is ________ kJ.
Substance
Ca(OH)2
H3AsO4
Ca(H2AsO4)2
H2O
A) -744.9
5)
B) -4519
∆Hfo
-986.6
-900.4
-2346.0
-285.9
C) -4219
D) -130.4
The combustion of titanium with oxygen produces titanium dioxide:
Ti(s) + O2(g) Æ TiO2(s)
When 0.721 g of titanium is combusted in a bomb calorimeter, the temperature of the calorimeter
increases from 25.00oC to 53.80oC. In a separate experiment, the heat capacity of the calorimeter is
measured to be 9.84 kJ/K. The heat of reaction for the combustion of a mole of Ti in this
calorimeter is ________ kJ/mol.
A) 4.98
B) none of these
C) -1.88 x 104
D) -311
6)
The specific heat capacity of liquid mercury is 0.14 J/g-K. How many joules of heat are needed to
raise the temperature of 5.00 g of mercury from 15.0oC to 36.5oC?
A) 7.7 x 102
B) 15
C) 36
D) 0.0013
7)
The photoelectric effect is __________.
A) electrons are contained in spherical orbits
B) the production of light by silicon solar cells when exposed to sunlight
C) the ejection of electrons by a metal when struck by light
D) the darkening of photographic film when exposed to an electric field
8)
In the Bohr model of the atom, __________.
A) electrons travel in eliptical paths called orbitals
B) electrons can have any energy
C) electron energies are quantized
D) electron paths are controlled by probability
9)
The lines in the emission spectrum of hydrogen result from __________.
A) energy given off in the form of visible light when an electron moves from a higher energy
state to a lower energy state
B) electrons given off by hydrogen when it burns
C) electrons given off by hydrogen as it cools
D) decomposing hydrogen atoms
10) All of the orbitals in a given subshell have the same value of the __________ quantum number.
A) principal
B) azimuthal
C) magnetic
D) A and B
11) Which one of the following is not a valid value for the magnetic quantum number of an electron in
a 5d subshell?
A) 2
B) 3
C) 0
D) 1
12) Which sketch represents an orbital with the quantum numbers n = 3, l = 0, and ml = 0?
A)
B)
C)
D)
13) Electrons that are in degenerate orbitals have the same __________.
A) magnetic quantum number
B) size
C) spatial orientation
D) energy
14) [Ar]4s23d104p3 is the electron configuration of a(n) __________ atom.
A) As
B) V
C) P
D) Sb
15) Which element would be expected to have chemical and physical properties closest to those of
fluorine?
A) S
B) Fe
C) Ne
D) Cl
16) Atomic radius generally increases as we move __________.
A) down a group and from right to left across a period
B) up a group and from left to right across a period
C) down a group and from left to right across a period
D) up a group and from right to left across a period
17) Of the following, which gives the correct order for atomic radius for Mg, Na, P, Si and Ar?
A) Mg > Na > P > Si > Ar
B) Ar > Si > P > Na > Mg
C) Si > P > Ar > Na > Mg
D) Na > Mg > Si > P > Ar
18) Of the choices below, which gives the order for first ionization energies?
A) Cl > S > Al > Ar > Si
B) Ar > Cl > S > Si > Al
C) Al > Si > S > Cl > Ar
D) Cl > S > Al > Si > Ar
19) Which ion in the isoelectronic series below has the largest radius in a crystal?
A) Al3+
B) Na+
C) O2-
D) F-
20) According to the Heisenberg Uncertainty Principle, it is impossible to know precisely both the
position and the __________ of an electron.
A) mass
B) color
C) momentum
D) shape
21)
22)
The oxide of which element below can react with hydrochloric acid?
A) sulfur
B) chlorine
C) nitrogen
D) sodium
Of the following oxides, __________ is the most acidic.
A) CaO
B) CO2
C) Al2O3
D) Li2O
23) Which alkali metal reacts with oxygen to form the oxide, M2O?
A) Li
B) Na
C) K
D) Rb
24) Of the ions below, only __________ has a noble gas electron configuration.
A) ClB) O2+
C) I+
D) K-
25) For a given arrangement of ions, the lattice energy increases as ionic radius __________ and as
ionic charge __________.
A) decreases, increases
B) increases, decreases
C) increases, increases
D) decreases, decreases
Problems
(10 points) Ammonia will burn to produce nitric acid, NO.
4 NH3(g) + 5 O2(g) Æ 4 NO(g) + 6 H2O(g)
Use the following chemical equations to determine the ∆Hrxn:
Equation
N2(g) + O2(g) Æ 2 NO(g)
N2(g) + 3 H2(g) Æ 2 NH3(g)
2 H2(g) + O2(g) Æ 2 H2O(g)
∆Hrxn(kJ)
180.6
-91.8
-483.7
2[N2(g) + O2(g) Æ 2 NO(g)]
2[2 NH3(g) Æ N2(g) + 3 H2(g)]
3[2 H2(g) + O2(g) Æ 2 H2O(g)]
2[180.6]
2[-[-91.7]]
3[-483.7]
2 N2(g) + 2O2(g) Æ 4 NO(g)]
4 NH3(g) Æ 2N2(g) + 6 H2(g)]
6 H2(g) + 3 O2(g) Æ 6 H2O(g)]
361.2
183.4
-1451.1
∆Hrxn = 361.2kJ + 183.4kJ + (-1451.1kJ) = -906.5kJ
(10 points) Give the electron configurations for the following atoms:
Ga
[Ar]4s23d104p1 or 1s22s22p63s23p64s23d104p1
Ca
[Ar]4s2 or 1s22s22p63s23p64s2
Br
[Ar]4s23d104p5 or 1s22s22p63s23p64s23d104p5
(5 points) Calculate the value of ∆Ho for the following reaction:
Fe2O3(s) + 6 HCl(g) Æ 2 FeCl3(s) + 3 H2O(g)
Substance
Fe2O3(s)
HCl(g)
FeCl3(s)
H2O(g)
∆Hfo
(kJ/mol)
-822.16
-92.30
-400
-241.82
∆Ho = {2[∆Hfo(FeCl3)] + 3[∆Hfo(H2O)]} - {1[∆Hfo(Fe2O3)] + 6[∆Hfo(HCl)]}
∆Ho = {2mol[-400kJ/mol] + 3mol[-241.82kJ/mol]} - {1mol[-822.16kJ/mol] + 6mol[-92.30kJ/mol]}
∆Ho = -149.5kJ