Name
Chemistry 111A General Chemistry
Practice Exam 2
Useful equations: E=q+w, q=mcT, E=h, =c,  = 4.79debye  Q(e)  r(Å),
 1
1
1 
QQ
 1.097  10 7 m 1  2  2  , E el   1 2

d
 n f ni 
Section 1 - Multiple Choice (mark correct answer on Scantron- 2.5 points each)
1.
2.
3.
4.
5.
Given the equation S (s) + O2 (g)  SO2 (g), H = -296 kJ, which of the following
statements is FALSE?
a)
The reaction is exothermic.
b)
When 1 mole sulfur is reacted, 296 kJ of energy is released.
c)
This is a combustion reaction
d)
The standard enthalpy of formation for SO2 (g) is –296 kJ
e)
Heat is absorbed during the reaction
Calculate the value of E for a system that loses 50 J of heat and has 150 J of work
performed on it by the surroundings.
a)
50 J
b)
100 J
c)
–100 J
d)
–200 J
e)
200 J
Which one of the following is an exothermic process?
a)
ice melting
b)
water evaporating
c)
boiling soup
d)
condensation of water vapor
e)
Ammonium thiocyanate and barium hydroxide are mixed at 25°C: the
temperature drops.
The value of H° for the reaction below is -126 kJ. How much heat is released
when 2.00 mol of NaOH is formed in the reaction?
2 Na2O2 (s) + 2 H2O (l)  4 NaOH (s) + O2 (g)
a)
252 kJ
b)
63 kJ
c)
3.9 kJ
d)
7.8 kJ
e)
–126 kJ

For which one of the following reactions is Hrxn
equal to the heat of formation of
the product?
a)
N2 (g) + 3 H2 (g)  2 NH3 (g)
b)
½ N2 (g) + O2 (g)  NO2 (g)
c)
6 C (s) + 6 H (g)  C6H6 (l)
d)
P (g) + 2 H2 (g) + Br (g)  PH4Br (l)
e)
12 C (g) + 11 H2 (g) + 11 O (g)  C12H22O11 (s)
6.
7.
8.
9.
10.
11.
12.
Of the following, which one is a state function?
a)
H
b)
q
c)
w
d)
heat
e)
none of the above
Which of the following transitions in the Bohr hydrogen atom results in the emission
of the highest-energy photon.
a)
n=1n=6
b)
n=6n=1
c)
n=6n=3
d)
n=3n=6
e)
n=1n=4
Which one of the following is an incorrect subshell notation?
a)
4f
b)
2d
c)
3s
d)
2p
e)
3d
All of the orbitals in a given subshell have the same value of the __________
quantum number(s).
a)
principal
b)
angular momentum (azimuthal)
c)
magnetic
d)
principal and angular momentum
e)
angular momentum and magnetic
Which one of the following atoms has the largest radius?
a)
Sr
b)
Ca
c)
K
d)
Rb
e)
Y
Which of the following correctly represents the second ionization of calcium?
a)
Ca (g)  Ca+ (g) + e –
b)
Ca+ (g)  Ca2+ (g) + e –
c)
Ca – (g) + e –  Ca2– (g)
d)
Ca+ (g) + e –  Ca2+ (g)
e)
Ca+ (g) + e –  Ca (g)
The chloride of which of the following metals should have the greatest lattice
energy?
a)
potassium
b)
rubidium
c)
sodium
d)
lithium
e)
cesium
13.
14.
Elements from opposite sides of the periodic table tend to form
a)
covalent compounds
b)
ionic compounds
c)
compounds that are gaseous at room temperature
d)
homonuclear diatomic compounds
e)
covalent compounds that are gaseous at room temperature
Given the electronegativities below, which covalent single bond is most polar?
Element:
H
C
N
O
Electronegativity: 2.1
2.5
3.0
3.5
a)
C–H
b)
N–H
c)
O–H
d)
O–C
e)
O–N
Section 2 Short answers (points as indicated)
(6)
1.
The value of H for the reaction below is –336 kJ
CH4 (g) + 3 Cl2 (g)  CHCl3 (l) + 3 HCl (g)
Calculate the heat released to the surroundings when 23.0 g of HCl is formed.
(8)
2.
10.5 g of KBr(s) at 24.2C is added to 125 g of
calorimeter. After all the KBr has dissolved
Calculate the enthalpy change for dissolving the
heat capacity of the combined solution is 3.9
surroundings.
H2O also at 24.2C in a coffee cup
the final temperature is 21.1C.
salt in J/g and kJ/mol. The specific
J/g.C and no heat is lost to the
(8)
3.
Given the following reactions:
C(s) + O2(g)  CO2(g)
H1 = -393.5 kJ
H2(g) + ½ O2(g)  H2O(l)
H2 = -285.8 kJ
C4H6(g) + 5½ O2(g)  3 H2O(l) + 4 CO2(g)
H3 = -2540.2 kJ
Find H for the following reaction:
4 C(s) + 3 H2(g)  C4H6(g)
(6)
(8)
4.
5.
Ham radio operators often broadcast on the 6-meter band.
a)
The frequency of this electromagnetic radiation is
b)
The energy of a single photon is
What is the longest wavelength photon that can ionize a hydrogen atom with its
electron in the n=2 level?
(8)
(8)
6.
7.
Indicate in each case whether the following sets of quantum numbers are
permissible for a single electron. If they are not permissible explain what is wrong.
a)
n=2, l=2, ml=1
b)
n=0, l=0, ml=0
c)
n=3, l=2, ml=-2
d)
n=4, l=2, ml=-3
Write the ground state electron configurations for the following elements (you may
write the core electrons as the noble gas) How many unpaired electrons does each
element have?
a)
C
b)
Ne
c)
K
d)
V
(7)
8.
How does atomic radius vary within the periodic table? Explain how the electronic
structure of the elements produces theses trends.
(6)
9.
The lithium bromide molecule has a dipole moment of 7.27 debye and a bond
length of 2.17 Å.
a)
What is the charge separation in lithium bromide?
b)
How would you describe the bonding in lithium bromide?