CHEM 10113, Exam 3
November 2, 2011
Name_____________________
(please print)
All equations must be balanced and show phases for full credit. Significant figures count, and
box your answers!
1. (11 points) In each blank write >, < or = as appropriate.
Cl-Cl bond polarity
=
H-H bond polarity
# of valence electrons in
SeO2
EA of Ta
=
<
# of valence electrons in
NO2–
EA of Cu
electronegativity of Re
<
electronegativity of Ru
size of Kr
>
size of Rb+
IE of Sr
<
IE of Sr+
Bond order of O2
>
Bond order of F2
Wavelength of IR light
>
Wavelength of X-rays
Energy of blue light
>
Energy of orange light
2. (12 points) Briefly define the following terms.
Shielding – screening of one electron from the nuclear charge by other electrons
around the same atom
Free radical – An atom or molecule containing an unpaired electron
Covalent bond – An interatomic attraction resulting from the sharing of electrons
between atoms
Expanded octet – In a Lewis structure, when the central atom of a molecule
bears more than 8 electrons, occurs for 3rd row or higher (hypervalency)
3. (10 points) SHOW ALL WORK. Use tabulated average bond energies
(appended to exam) to estimate the enthalpy of the following reaction.
H2O2(g)  H2O(g) + ½ O2(g)

+½
Hrxn =  [H bonds broken] -  [H bonds formed]
Hrxn = [2(O-H) + (O-O)] – [2(O-H) + 1/2(O=O)]
Hrxn = [2(464 kJ/mol) + 142 kJ/mol] – [1/2(498 kJ/mol) + 2(464 kJ/mol)]
Hrxn = -107 kJ/mol
1
4. (15 pts) SHOW ALL WORK. A heat lamp produces 32.8 watts of power at a
wavelength of 6.5 m. How many photons are emitted per second? (1 watt = 1
J/s)
32.8 watts 1 J/s = 32.8 J/s
1 watt
 = 6.5 m 10-6 m = 6.5 x 10-6 m
1 m
 = c = 2.998 x 108 ms-1 = 4.61 x 1013 s-1
 6.5 x 10-6 m
E=h = (6.626x10-34 J s/photons)(4.61 x 1013 s-1) = 3.05 x 10-20 J/photon
32.8 J x photons
= 1.1 x 1021 photons/s
s
3.05 x 10-20 J
5. (3 points) If the value of ml for an electron in an atom is –3, what is the
smallest value of l that the electron could have?
ml = -3; l= 3
6. (2 point) Which quantum number is related to shape of the orbital?
Shape  l
7. (12 points) Fill in the blanks in the following equations. For coefficients of 1,
please write “1” rather than leaving blank.
Example:
__ MgCl2(___) + __ AgNO3(___)  __ ____(s) + 1 ______(___)
Answer:
1 MgCl2(aq) + 2 AgNO3(aq)  2 AgCl(s) + 1 Mg(NO3)2(aq)
a) _1__ __I2___ (
b) _1_ H2(
g )
+ F2(
s)
+ __Pt__ ( s )  _1_ PtI2(
g )
s )
 _2__ __HF__ (g)
8. (6 points) Name the element or ion:
a. Its valence electron configuration is ns1 and its most stable ion has the same
electron configuration as krypton.__Rb____
b. It has 7 unpaired valence electrons and is a lanthanide.__Eu___
9. (6 points) Give the complete electron configuration for a. P2– ion, and b. Be.
a) P2- : 1s22s22p63s23p5
2
b) Be: 1s22s2
10. (5 points) Write the standard formation reaction for Cu(NO3)2·3H2O(s).
Cu(s) + N2(g) + 9/2 O2(g) + 3 H2(g)  Cu(NO3)2·3H2O(s)
11. (6 points) Give the short-hand electron configurations for a. Co+, and b. Pb.
a) Co+: [Ar]3d8
b) Pb: [Xe]6s24f145d106p2
12. (6 points) Give the valence electron configurations of a. Ge, and b. Eu.
a) Ge: 4s24p2
b) Eu: 6s24f7
13. (6 points) Write the chemical equations for a. the second ionization energy of
zinc, and b. the EA of Y.
a) Zn+ (g)  Zn 2+(g) + eb) Y(g) + e-  Y-(g)
14. (6 points) Contrast three properties of alkali metals and three properties of
the noble gases.
Alkali metals
Noble gases
Easily reactive w/halogens
Non-reactive
Metallic/ high mp, bp
Nonmetals/ low mp, bp
Low IE
High IE
15. (3 points) The bond order of the N-O bond in NO2− is ___1.5____.
16. (10 points) SHOW ALL WORK. Calculate the enthalpy change for the
reaction
Ca2+(aq) + 2 OH–(aq) + CO2(g)  CaCO3(s) + H2O(l)
by manipulating the following equations.
FLIP [CaCO3(s)  CaO(s) + CO2(g)] H = [–178.1 kJ] FLIP
FLIP [CaO(s) + H2O(l)  Ca(OH)2(s)] H = [–65.3 kJ] FLIP
FLIP [Ca(OH)2(s)  Ca2+(aq) + 2 OH–(aq)] H = [–16.2 kJ] FLIP
3
Perform the manipulations to receive the following equations:
CO2(g) + Ca(s)  CaCO3(s)
H = +178.1 kJ
Ca(OH)2(s)  CaO(s) + H2O(g)
H = + 65.3 kJ
Ca2+(aq) + 2 OH –(aq)  Ca(OH)2 (s)
+ H = +16.2 kJ
+259.6 kJ
17. (24 points) Write the complete Lewis electron dot formulas for each of the
molecules below. Please put the final answers in the boxes; anything outside of
the boxes will not be graded.
Formal Charge = (# of valence e– in the isolated atom) - (# of bonds to the atom)
- (# of unshared electrons on the atom)
O22–
NF3
ClO3–
<->
<->
PCl4+
4
18. (7 points) SHOW ALL WORK. Use the Born-Haber cycle as shown to
determine the value of H for step 3.
-349 kJ
+122 kJ
+108 kJ
-788 kJ
-411 kJ
5
Hf = H step 1 + H step 2 + H step 3 + H step 4 + H step 5
-411 = 108 + 122 + H step 3 + -349 + -788
H step 2 = 496
CHEM 10113, Exam 3
November 2, 2011
Name_____________________
(please print)
All equations must be balanced and show phases for full credit. Significant figures count, and
box your answers!
1. (11 points) In each blank write >, < or = as appropriate.
IE of Ca+
<
IE of Ca2+
# of valence electrons in
OCN–
polarity of Sb-Cl bond
<
>
# of valence electrons in
NO2–
polarity of Cl-Cl bond
Frequency of radiowaves
<
Frequency of UV light
Bond order of CO
=
Bond order of N2
Size of S2– ion
>
Size of Ar ion
EA of In
>
EA of Hf
electronegativity of I
>
electronegativity of Au
Wavelength of gamma
rays
<
Wavelength of X-rays
2. (12 points) Briefly define the following terms.
Diamagnetic – Repelled by a magnetic field, having all paired electrons
Ionic bond – The electrostatic attraction between a positive and a negative ion
resulting from complete transfer of one or more electrons from one atom to
another
Emission spectrum – Spectrum of frequencies of electromagnetic radiation
emitted by an atom or molecule when it relaxes to a lower energy state
Ground state – The state of an atom or molecule in which all electrons are in the
lowest possible energy levels
3. (10 points) SHOW ALL WORK. Use tabulated average bond energies
(appended to exam) to estimate the enthalpy of the following reaction.
Cl2CF2(g) + F2(g)  CF4(g) + Cl2(g)
6
+

+
H rxn =  [H bonds broken] -  [H bonds formed]
H rxn = [2(C-F) + 2(C-Cl) + (F-F)] – [4(C-F) + (Cl-Cl)]
H rxn = [2(485 kJ/mol) + 2(339 kJ/mol) + 159 kJ/mol] – [4(485 kJ/mol) + (243
kJ/mol)]
H rxn = -376 kJ/mol
4. (15 pts) SHOW ALL WORK. A heat lamp produces 34.6 watts of power at a
wavelength of 5.5 m. How many photons are emitted per second? (1 watt = 1
J/s)
34.6 watts 1 J/s = 34.6 J/s
1 watt
 = 5.5 m 10-6 m = 5.5 x 10-6 m
1 m
 = c = 2.998 x 108 ms-1 = 5.45 x 1013 s-1
 5.5 x 10-6 m
E=h = (6.626x10-34 J s/photons)(5.45 x 1013 s-1) = 3.61 x 10-20 J/photon
34.6 J x photons
= 9.6 x 1020 photons/s
-20
s
3.61 x 10 J
5. (3 points) If the value of ml for an electron in an atom is –3, what is the
smallest value of n that the electron could have?
ml = -3; n= 4
6. (2 point) Which quantum number is related to spatial orientation?
Spatial orientation  ml
7. (12 points) Fill in the blanks in the following equations. For coefficients of 1,
please write “1” rather than leaving blank.
Example:
__ MgCl2(___) + __ AgNO3(___)  __ ____(s) + 1 ______(___)
Answer:
1 MgCl2(aq) + 2 AgNO3(aq)  2 AgCl(s) + 1 Mg(NO3)2(aq)
a) _1__ __Cl2___ (
g )
+ __Zn___ (
s )
 _1__ ZnCl2(
7
s )
b) _1__ I2( s ) + F2( g )  _2__ _IF___ (g)
8. (6 points) Name the element or ion:
a. Its electron configuration is 1s22s22p1 and it has a +1 charge.__C+___
b. It has 5 unpaired valence electrons and its highest principle level is 6._Re___
9. (6 points) Give the complete electron configurations for a. Si+ ion, and b. C.
a) Si+: 1s22s22p63s23p1
b) C: 1s22s22p2
10. (5 points) Write the standard formation reaction for MgSO4·7H2O(s).
Mg(s) + S(g) + 11/2 O2(g) + 7 H2(g)  MgSO4·7H2O(s)
11. (6 points) Give the short-hand electron configurations for a. Os+, and b. Te.
a) Os+: [Xe]4f145d7
b) Te: [Kr]5s24d105p4
12. (6 points) Give the valence electron configurations of a. Sn, and b. Nd.
a) Sn: 5s25p2
b) Nd: 6s24f4
13. (6 points) Write the chemical equations for a. the second ionization energy of
cadmium, and b. the EA of Db.
a) Cd+(g)  Cd2+(g) + eb) Db(g) + e-  Db- (g)
14. (6 points) Contrast three properties of alkali metals and three properties of
the halogens.
Alkali metals
halogens
Easily oxidized
Easily reduced
Low EA
High EA
Low IE
High IE
15. (3 points) The bond order of the P-O bond in PO43− is ___1.25____.
16. (10 points) SHOW ALL WORK. Calculate the enthalpy change for the
reaction
C(s) + 2 H2(g)  CH4(g)
by manipulating the following equations.
8
C(s) + O2(g)  CO2(g) H = –393.5 kJ
x2[ H2(g) + ½ O2(g)  H2O(l) ] H = [–285.8 kJ] x2
FLIP [ CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(l)] H = [–890.3 kJ] FLIP
Perform manipulations to receive the following equations:
H = –393.5 kJ
H = –571.6 kJ
H = +890.3 kJ
-74.8 kJ
C(s) + O2(g)  CO2(g)
2 H2(g) + O2(g)  2 H2O(l)
CO2(g) + 2 H2O(l)  CH4(g) + 2 O2(g)
17. (24 points) Write the complete Lewis electron dot formulas for each of the
molecules below. Please put the final answers in the boxes; anything outside of
the boxes will not be graded.
Formal Charge = (# of valence e– in the isolated atom) - (# of bonds to the atom)
- (# of unshared electrons on the atom)
NO–
IF4–
NO3–
9
<->
<->
CCl4
18. (7 points) SHOW ALL WORK. Use the Born-Haber cycle as shown to
determine the value of H for step 4.
+496 kJ
+122 kJ
+108 kJ
-788 kJ
-411 kJ
10
Hf = H step 1 + H step 2 + H step 3 + H step 4 + H step 5
-411 = 108 + 122 + 496 + H step 4 + -788
H step 2 = -349
CHEM 10113, Exam 3
November 2, 2011
Name_____________________
(please print)
All equations must be balanced and show phases for full credit. Significant figures count, and
box your answers!
1. (11 points) In each blank write >, < or = as appropriate.
bond order of F2
<
bond order of N2
EA of V
<
EA of Zn
 of microwaves
electronegativity of P
>
>
 of yellow light
electronegativity of Mg
>
size of Kr
IE of Ar–
<
IE of Ar
Energy of radiowaves
<
Energy of microwaves
C=O bond polarity
>
H-H bond polarity
# of valence electrons in
H2CO2
<
# of valence electrons in
Cl2CO
size of Br
–
2. (12 points) Briefly define the following terms.
Effective nuclear charge – The positive charge experienced by an electron in a
multielectron atom, when taking shielding into account
Electron sea model – Model of metallic bonding in which cations are considered
to be fixed points within a mobile “sea” of electrons
degenerate – of equal energies
Paramagnetic – Attracted by a magnetic field, having unpaired electrons
3. (10 points) SHOW ALL WORK. Use tabulated average bond energies
(appended to exam) to estimate the enthalpy of the following reaction.
H2C=CH2(g) + Br2(g)  BrH2C-CH2Br(g)
11
+

H rxn =  [H bonds broken] -  [H bonds formed]
H rxn = [(C=C) + (Br-Br)] – [2(Br-C) + (C-C)]
H rxn = [611 kJ/mol + 193 kJ/mol] – [2(285 kJ/mol) + 347 kJ/mol]
H rxn = -113 kJ/mol
4. (15 pts) SHOW ALL WORK. A heat lamp produces 40.0 watts of power at a
wavelength of 6.1 m. How many photons are emitted per second? (1 watt = 1
J/s)
40.0 watts 1 J/s = 40.0 J/s
1 watt
 = 6.1 m 10-6 m = 6.1 x 10-6 m
1 m
 = c = 2.998 x 108 ms-1 = 4.91 x 1013 s-1
 6.1 x 10-6 m
E=h = (6.626x10-34 J s/photons)(4.91 x 1013 s-1) = 3.25 x 10-20 J/photon
40.0 J x photons
= 1.2 x 1021 photons/s
-20
s
3.25 x 10 J
5. (3 points) If the value of ml for an electron in an atom is –4, what is the
smallest value of n that the electron could have?
ml = -4; n= 5
6. (2 point) Which quantum number is related to energy?
Energy  n
7. (12 points) Fill in the blanks in the following equations. For coefficients of 1,
please write “1” rather than leaving blank.
Example:
__ MgCl2(___) + __ AgNO3(___)  __ ____(s) + 1 ______(___)
Answer:
1 MgCl2(aq) + 2 AgNO3(aq)  2 AgCl(s) + 1 Mg(NO3)2(aq)
a) _2__ Li (
s )
+ _2__ H2O(l)  __H2___(g) + _2__ __LiOH___(aq)
b) _2__ __Cs__ ( s
)
+ Br2( l )  _2__ CsBr(
12
s )
8. (6 points) Name the element or ion:
a. Its electron configuration is 1s22s22p5 and it has a -1 charge. __O–___
b. It has 4 unpaired valence electrons and its highest principle level is 4.__Cr__
9. (6 points) Give the complete electron configurations for a. Cl+ ion, and b. F.
a) Cl+: 1s22s22p63s23p4
b) F: 1s22s22p5
10. (5 points) Write the standard formation reaction for CuSO4·5H2O(s).
Cu(s) + S(g) + 9/2 O2(g) + 5 H2(g)  CuSO4·5H2O(s)
11. (6 points) Give the short-hand electron configurations for a. Au+, and b. Po.
a) Au+: [Xe]4f145d10
b) Po: [Xe]6s24f145d106p4
12. (6 points) Give the valence electron configurations of a. Pb, and b. Ce.
a) Pb: 6s26p2
b) Ce: 6s24f15d1
13. (6 points) Write the chemical equations for a. the second ionization energy of
mercury, and b. the EA of Re.
a) Hg+(g)  Hg2+(g) + eb) Re(g) + e-  Re-(g)
14. (6 points) Contrast three properties of halogens and three properties of the
noble gases.
halogens
Noble gases
Diatomics in nature
Not diatomics
High EA
Low EA
Very reactive
Non-reactive
15. (3 points) The bond order of the C-O bond in HCO2− is ___1.5______.
16. (10 points) SHOW ALL WORK. Calculate the enthalpy change for the
reaction
2 HCl(g) + F2(g)  2 HF(l) + Cl2(g)
by manipulating the following equations.
X1/2 [4 HCl(g) + O2(g)  2 H2O(l) + 2 Cl2(g) ] H = [–202.4 kJ] x1/2
X2 [½ H2(g) + ½ F2(g)  HF(l) ] H = [–600.0 kJ] x2
13
FLIP [H2(g) + ½ O2(g)  H2O(l)] H = [–285.8 kJ] FLIP
Perform manipulations to give the following equations:
2 HCl(g) + ½ O2 (g)  H2O(l) + Cl2(g)
H2(g) + F2(g)  2HF(l)
H2O  H2(g) + ½ O2(g)
H = -101.2 kJ
H= -1200.0 kJ
+ H= +285.8 kJ
-1015.4 kJ
17. (24 points) Write the complete Lewis electron dot formulas for each of the
molecules below. Please put the final answers in the boxes; anything outside of
the boxes will not be graded.
Formal Charge = (# of valence e– in the isolated atom) - (# of bonds to the atom)
- (# of unshared electrons on the atom)
BrO–
ClO4–
<->
<->
14
<->
SBr2
AsCl4+
18. (7 points) SHOW ALL WORK. Use the Born-Haber cycle as shown to
determine the value of H for step 2.
-349 kJ
+496 kJ
+108 kJ
15
-788 kJ
Hf = H step 1 + H step 2 + H step 3 + H step 4 + H step 5
-411 = 108 + H step 2 + 496 + -349 + -788
H step 2 = 122
16