CHEMISTRY 102 B/C
HOUR EXAM I
Fall 2010
page 1
1. (4) The atomic weight of Cu is 63.546. There are only two naturally occurring
isotopes of copper, 63Cu and 65Cu. The natural abundance of the 63Cu isotope
must be approximately:
a) 10%
b) 30%
c) 50%
d) 70%
e) 90%
2. (4) Coenzyme A contains one sulfur atom per molecule. When it is decomposed the
sulfur is converted to sulfide. A 56.0 g sample of coenzyme A is decomposed and
the sulfide released is completely precipitated by its reaction with
73 mL of 2.00 M AgNO3. What is the molar mass of coenzyme A?
a) 192 g/mol b) 384 g/mol c) 576 g/mol d) 767 g/mol e) 1534 g/mol
3. (3) A particular isotope of an element has a mass number of 152. There are 60
electrons in the +2 ion of the isotope. Identify the element, the number of protons
and the number of neutrons of this particular isotope.
a)
b)
c)
d)
e)
62 protons, 90 neutrons : Sm
66 protons, 86 neutrons : Dy
60 protons, 92 neutrons : Nd
63 protons, 89 neutrons : Eu
57 protons, 95 neurons : La
4. (4) A sample of water has a mass of 234.9 g at 24.0o C. The density of water at
24.0 oC is 0.99707 g/mL. What is the volume of the water, in L and to the correct
number of significant figures.
a) 2.3559 x 10-1
b) 2.356 x 10-1
c) 2.36 x 10-1 d) 2.36 x 101
e) 2.356 x 101
5. (4) Calculate the approximate molarity of water, at 25o C. (The density of water at
this temperature is defined as 1.0 g/mL).
a) 1.0 M
b) 18 M
c) 56 M
d) 1.0 x 102 M
e) 3.2 x 102 M
CHEMISTRY 102 B/C
HOUR EXAM I
Fall 2010
page 2
6. (3) How many of the following compounds are strong electrolytes?
CH3OH
CaCl2
HClO4
NH4NO3
Be(OH)2
a) 1
b) 2
c) 3
d) 4
e) 5
7. (4) Ethanol, C2H60 is being added to gasoline to provide a renewable fuel for cars. It
burns as shown below in an unbalanced reaction:
C2H6O (l) + O2 (g)  CO2 (g) + H2O (l)
If 150 g of ethanol is mixed with 192 g of oxygen, what mass of carbon dioxide
will be produced? (Molar masses C2H6O= 46.07 g/mol, O2 = 32.00 g/mol,
CO2 = 44.01 g/mol, H2O = 18.02 g/mol).
a)
b)
c)
d)
e)
132 g CO2
176 g CO2
194 g CO2
264 g CO2
388 g CO2
8. (4) A compound contains only carbon, hydrogen and oxygen. Combustion of
7.30 mg of the compound yields 10.68 mg of carbon dioxide and 4.37 mg of
water. What is the empirical formula of this compound?
a) CHO
b) C2HO
c) CH2O
d) CHO2
e) none of these (a-d)
9. (4) A sample of copper sulfate pentahydrate, CuSO4 . 5H2O, contains 3.782 g of Cu.
How many grams of oxygen are in this same sample?
a) 0.952 g
b 3.809 g
c) 4.761 g
d) 7.618 g
e) 8.57 g
10. (3) The element dysprosium, Dy, forms an oxide with the formula Dy2O3. The
corresponding bromide of dysprosium has the formula:
a) Dy2Br3
b) DyBr
c) DyBr2
d) DyBr3
e) Dy3Br2
CHEMISTRY 102 B/C
HOUR EXAM I
Fall 2010
page 3
11. (3) Which element is expected to be most chemically similar to phosphorus?
a) S
b) As
c) Se
d) Ge
e) Si
12. (4) Which of the following compounds is named correctly?
a)
b)
c)
d)
e)
SnO2
NaNO2
NO
Al2S3
Na2O2
tin(II) oxide
sodium nitrate
nitrogen oxide
dialuminum trisulfide
sodium peroxide
Use the following information to answer the next two (2) questions.
When 50.0 mL of a 1.00 M aqueous solution of Fe(NO3)3 is mixed with 50.0 mL of a
1.00 M aqueous solution of NaOH, a precipitate forms.
13. (4) What ions remain in solution after the reaction is completed?
a)
b)
c)
d)
e)
Fe3+ and OHFe3+, Na+ and NO3Fe3+, OH-, Na+ and NO3Na+ and NO3Na+, NO3-, OH-
14. (4) Determine the mass of the solid produced in this reaction.
a) 0.35 g
b) 1.78 g
c) 2.67 g
d) 5.34 g
e) 7.96 g
CHEMISTRY 102 B/C
HOUR EXAM I
Fall 2010
page 4
15. (4) A fluoride salt of an alkaline earth metal has a molar mass of 78 g/mol. What is
the formula of this salt?
a) CaF2
b) NaF2
c) KF
d) SrF2
e) LiF
16. (4) Automobile airbags inflate when sodium azide, NaN3, decomposes explosively to
form the elements, Na (s) and N2 (g). How many grams of NaN3 are needed to
produce 5.00 g of nitrogen gas? (Molar masses, NaN3 = 65.02 g/mol, Na = 22.99,
N2 = 28.02 g/mol)
a) 23.2 g
b) 17.4 g
c) 11.6 g
d) 8.58 g
e) 7.73 g
17. (4) In an experiment, 30.0 mL of a 0.35 M solution of Ca(OH)2 are neutralized with
0.766 g of an acid. Which of the following acids was used in the experiment?
a)
b)
c)
d)
e)
HCl (MW = 36.46 g/mol)
HNO3 (MW = 63.01 g/mol)
HI (MW = 27.91 g/mol)
HClO4 (MW = 100.46 g/mol)
HBr (MW = 80.91 g/mol)
18. (4) When NO is oxidized, which of the following compounds can not be formed?
a)
b)
c)
d)
e)
HNO3
N2O
N2O5
N2O4
NO3-
CHEMISTRY 102 B/C
HOUR EXAM I
Fall 2010
page 5
19. (4) Which of the following is the net ionic equation when 0.10 M solutions of
magnesium chloride and potassium sulfate are mixed together?
a)
b)
c)
d)
e)
MgCl2 (aq) + K2SO4 (aq)  MgSO4 (s) + 2 KCl (aq)
MgCl2 (aq) + K2SO4 (aq)  2 KCl (s) + CaSO4 (aq)
Mg2+ (aq) + SO42- (aq)  MgSO4(s)
2 K+ (aq) + 2 Cl- (aq)  2 KCl (s)
No reaction takes place
Use the following information to answer the next two questions.
Balance the following reaction:
H2SO4 (aq) + I- (aq)  H2S (g)+ I2 (s)
20. (4) Which of the following statement is true about this reaction?
a)
b)
c)
d)
e)
I- is reduced
H2S is the reducing agent
H+ is reduced
H2SO4 is the oxidizing agent
H+ is oxidized
21. (4) What is the total of the coefficients in the balanced reaction?
a) 5
b) 8
c) 10 d) 13 e) 26
22. (4) What is the oxidation state change for sulfur in this reaction?
a)
b)
c)
d)
e)
4+  2+
6+  2+
6+ 27+  58+  2-
CHEMISTRY 102 B/C
HOUR EXAM I
Fall 2010
page 6
23. (4) The analysis of a gaseous compound revealed that it was 85.7% C and 14.3% H
by mass. When 1.77 g of the gas is stored in a 1.500 L flask at 17oC it has a
pressure of 1.10 atm. What is the molecular formula of the compound?
a) CH2
b) CH4
c) C2H2
d) C2H4
e) C2H6
24. (4) An unknown diatomic gas has a density of 3.164 g/L at STP. What is the identity
of the gas?
a) N2O4
b) SO2
c) Kr
d) Cl2
e) Br2
25. (4) Consider the following reaction:
2 N2O5 (g)  4 NO2 (g) + O2 (g)
0.500 mol of N2O5 is initially placed in a 5.00 L container at 27oC. What is the
total pressure in the 5.00 L container after all of the N2O5 decomposes to form the
products, all at 27oC?
a) 6.15 atm
b) 4.10 atm
c) 3.08 atm
d) 2.05 atm
E) 1.03 atm
26. (4) A solution is made by mixing 50.0 mL of 6.00 M HCl with 400.0 mL of 0.250 M
HCl. This mixture is diluted by adding water until the final volume in 800.0 mL.
What is the molarity of the final solution of HCl?
a) 0.125 M
b) 0.250 M
c) 0.500 M
d) 0.750 M
e) 1.00 M
CHEMISTRY 102 B/C
HOUR EXAM I
Fall 2010
page 7
Solubility Rules:
1.
Most nitrate salts are soluble.
2.
Most salts of alkali metals and ammonium cations are soluble.
3.
Most chloride, bromide and iodide salts are soluble.
Exceptions: salts containing Ag+, Pb2+ and Hg22+ ions are insoluble
4.
Most sulfate salts are soluble.
Exceptions: sulfates containing Ca2+, Ba2+, Pb2+ and Hg22+ ions are insoluble
5.
Most hydroxide salts are insoluble.
Exceptions: hydroxides containing alkali metals, ammonium, Ba2+, Sr2+ and Ca2+
ions are soluble
6.
Most sulfide, carbonate, chromate and phosphate salts are insoluble.
Exceptions: salts of alkali metals and ammonium cations are soluble
Useful Constants and equations:
K = oC + 273
M = Molarity = mol solute
L solution
PV = nRT
% yield = actual yield x 100
theoretical yield
R = 0.08206 L atm / mol K
STP = 1 atm, 273 K
Avogadro's number = 6.022 x 1023
PM=dRT where d=density, M=molar mass
1 atm = 760 torr = 760 mm Hg
d = density = mass/volume
mass % of A = mass of A x 100
total mass
P1V1 = P2V2
n1T1 n2T2