Download Midterm 2 from Summer 2012

CH 221
General Chemistry
Spring 2012
Name:
Midterm Examination 2
Useful Information is located on the last two pages of the Exam.
Multiple Choice Questions
A carton of Morton's Iodized Salt, NaCl with traces of potassium iodide, has a reported
mass of 26 oz (737g).
1.
Assuming the sample is nearly pure NaCl, how many moles of NaCl are in the
carton?
a)
b)
c)
d)
2.
How many formula units of NaCl are contained in the carton?
a)
b)
c)
d)
3.
2.3 x 1022 NaCl formula units
7.6 x 1024 NaCl formula units
6.7 x 1023 NaCl formula units
3.5 x 1019 NaCl formula units
How many atoms are contained in the carton?
a)
b)
c)
d)
4.
0.544 mole NaCl
1.93 mole NaCl
7.85 mole NaCl
12.6 mole NaCl
2.3 x 1022 atoms
6.8 x 1023 atoms
1.5 x 1025 atoms
3.7 x 1024 atoms
Suppose I synthesize 0.35 mole of Cuprous Chloride, CuCl. What mass of product
has been obtained?
a)
b)
c)
d)
2.56 g
34.7 g
54.2 g
103 g
5.
What is the percentage by mass Carbon in Morphine, C17H19NO3?
a)
b)
c)
d)
6.
Hydrazine is an extremely combustible compound composed of Nitrogen and
Hydrogen that is used as a fuel for ICBM's. This compound has a composition of
87.42% Nitrogen and 12.58% Hydrogen. What is the Empirical Formula of
hydrazine?
a)
b)
c)
d)
7.
H2SO4
NaCl
HNO3
H3PO4
What salt is produced when Nitric Acid (HNO3) is neutralized by Potassium
Hydroxide (KOH)?
a)
b)
c)
d)
9.
N2H2
NH2
N2H
NH
Which of the following is not an acid:
a)
b)
c)
d)
8.
45.2%
62.7%
71.6%
88.4%
KH
KNO3
H2O
HONO3
When Cesium Ion combines with Phosphate Ion, the resulting compound will have
the following chemical formula:
a)
b)
c)
d)
Cs3PO4
Cs2PO4
Cs(PO4)2
Cs(PO4)3
10. When elemental Calcium combines with elemental Fluorine, the resulting
compound is expected to have a chemical formula of:
a)
b)
c)
d)
11.
CaF
Ca2F
CaF2
Ca2F2
The charge on the cation in MnO2 is:
a)
b)
c)
d)
Mn+
Mn2+
Mn3+
Mn4+
12. What is the Oxidation State of the Sulfur in H2SO4?
a)
b)
c)
d)
S2+
S4+
S6+
S8+
13. What is the Oxidizing Agent in the following chemical reaction:
N2(g) + 3 H2(g)
2 NH3(g)
a) N2
b) H2
c) NH3
14. 10.0 mL of a 6.5 M solution is diluted to 250 mL. What is the concentration of the
diluted solution?
a)
b)
c)
d)
1.5 M
0.26 M
0.047 M
0.0081 M
15. What volume of a 6.0 M stock NaOH solution is required to prepare 400 mL of 1 M
NaOH?
a)
b)
c)
d)
15.0 mL
33.3 mL
42.1 mL
66.7 mL
16. Determine Ho at 298K for the following reaction:
2 Cl2(g) + 2 H2O(l)
Useful Data:
Cmpd
H2O(l)
HCl(g)
a)
b)
c)
d)
202.5 kJ/mol
57.6 kJ/mol
-32.1 kJ/mol
-157.2 kJ/mol
4 HCl(g) + O2(g)
Hfo(298) [kJ/mol]
-285.85
-92.30
Short Answer Questions
1.
Neutralization is a reaction between "equivalent" amounts of Acid and Base to produce a neutral
aqueous solution. Consider the neutralization of Sulfuric Acid by the Base Sodium Hydroxide:
H2SO4(aq) + 2 NaOH(aq)
Na2SO4(aq) + 2 H2O
45.7 mL of 0.500 M H2SO4 is required to completely neutralize an NaOH solution. How many
grams of NaOH were required to carry-out this neutralization?
2.
Hydrogen Cyanide, HCN, can be made in a two step process. First, Ammonia is
reacted with Oxygen to give Nitrogen Oxide:
4 NH3(g) + 5 O2(g)
4 NO(g) + 6 H2O(g)
Then, Nitrogen Oxide is reacted with Methane, CH4:
2 NO(g) + 2 CH4(g)
2 HCN(g) + 2 H2O(g) + H2(g)
We wish to prepare Hydrogen Cyanide from the available 24g of Ammonia and 25g
of Methane.
a)
How much Nitrogen Oxide can theoretically be produced in the first reaction.
b)
How many grams of Hydrogen Cyanide can theoretically be produced?
3.
Identify the products of the following reaction. Identify any products which may
precipitate. Write the Total and Net Ionic Equations for this reaction.
AgNO3(aq) + MgCl2(aq)
4.
A 30.5g sample of an alloy at 93.0oC is placed into 55.0g of Water at 22.0oC in an
insulated coffee cup calorimeter. I the final temperature of the system is 31.4oC,
what is the Specific Heat of the alloy? Assume the calorimeter absorbs no heat.
5.
Determine Ho for the conversion of Diamond into Graphite:
C(diamond)
C(graphite)
Useful Data
C(diamond) + O2(g)
CO2(g)
Ho = -395.4 kJ
C(graphite) + O2(g)
CO2(g)
Ho = -393.5 kJ
Appendix - Useful Data
Constants
Avogadro's Number
NA = 6 x 1023 entities / mole
Solubility Rules for Ionic Compounds
Substances
Solubility
Common Exceptions
Alkali metals and
Ammonium compounds
Soluble
None
Nitrates, Acetates, Chlorates,
and Perchlorates
Soluble
None
Chlorides, Bromides, and
Iodides
Soluble
Ag+ and Hg22+ halides and
Hg2+ iodides are insoluble.
PbCl2, PbBr2, PbI2 and HgBr2
are slightly soluble.
Sulfates
Soluble
Sr2+, Ba2+, Pb2+ and Hg22+
sulfates are insoluble. CaSO4
and Ag2SO4 sulfate are
slightly soluble.
Hydroxides
Insoluble
Alkali metal and Ba2+
hydroxides are soluble.
Sr(OH)2 and Ca(OH)2 are
slightly soluble.
Sulfides, Carbonates,
Phosphates
Insoluble
Alkali metal and NH4+
compounds are soluble. CaS,
SrS and BaS are soluble.