Name:
Signature:
___________________________
____________________________
12/03
Exam III
A
Chemistry 141
Fall 2015
Dr. Steven C. Haefner
Bridgewater State University
1. (20 pt)
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2. (20 pt)
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3. (18 pt)
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4. (18 pt)
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5. (20 pt)
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6. (20 pt)
___________
7. (45 pt)
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8. (39 pt)
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Total (200 pt)
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Scaled Total (150 pt)
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Percent Total (100%)
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This exam consists of a total of 9 pages including the cover page, an equation sheet and the periodic table found
on the last page. Please make sure that your exam is complete before beginning. Feel free to remove the
periodic table if you desire.
You will have a total of 55 minutes to complete the exam. Please budget your time accordingly. Read each
problem carefully. In order to receive full credit you must show all work.
Your signature on this exam signifies that you will faithfully adhere to and up hold the principles of the
Bridgewater State University Honor Code. You are not allowed to retrieve information or formulas from your
calculator. Such actions will be interpreted as a violation of the Honor Code.
Read each question carefully. If you feel that a question needs clarification, please raise your hand and I will
assist you as much I can.
1.
2
Balance the following chemical reactions. (20 pts)
(a) Write the balance chemical equation for the combustion of 1,3-pentadiene, C5H8
(b) .
2.
CrSO4 (aq) +

Tl2SO4 (aq)
Tl (s)
+
Cr2(SO4)3 (aq)
Consider the following reaction:
Sn (s)
+
2 AgClO (aq)

2 Ag (s)
(a) Write the complete ionic equation for this reaction.
(b) Write the net ionic equation for this reaction.
+
Sn(ClO)2 (aq)
3.
(a)
(b)
3
Provide brief answers for the following questions. USE CHEMICAL FORMULAS for compounds. (18 pts)
Both Cu2Se and CuSe are considered insoluble compounds. Like all insoluble compounds, very small
amounts of either compound will dissolve to some extent. Which one is expected to be the Least
soluble of the two compounds. Briefly explain why.
Which solutions could you mix to prepare solid AlPO4. You must give solutions of complete
compounds
(c) Many nitrated organic molecules are considered to be explosive. Based on the structure provided below,
write the empirical formula for the compound below.
4.
For each of the following predict whether or not a reaction will take place to any significant extent.
If a reaction does take place, write out the balanced net ionic equation for it. (18 pts)
(a)
Aqueous calcium bromide is mixed with aqueous lithium phosphate
(b)
RbI (aq) mixed with Na2CO3 (aq)
(c)
Cr(ClO4)3 (aq) added to Sr(OH)2 (aq)
4
5. Most transition metals are found in the earth as oxides. A particular oxide of Molybdenum, Mo, was found
to contain 70.58 % Mo by mass. Determine the empirical formula for this oxide of molybdenum. (20 pts)
6.
Determine the molarity of an aqueous Iron (III) hydrogen phosphate solution prepared by dissolving 45.80
grams of Fe2(HPO4)3 in enough water to produce 750.0 mL of solution. Report the concentration to the
correct number of significant figures. (20 pts)
5
7.
Arsine, AsH3, is a highly toxic gas that has been used in the semiconductor industry. It can be prepared by treating zinc
arsenide, Zn3As2 (mol. mass = 346.01 g/mol) with concentrated solutions of nitric acid (mol. mass = 63.01 g/mol) according to
the balanced chemical reaction shown below:
Zn3As2 (s)
+ 6 HNO3 (aq) 
2 AsH3 (g) + 3 Zn(NO3)2 (aq)
(a) How many mL of a 2.50 M HNO3 (aq) solution would be required to react completely with 35.80 g of
Zn3As2 (s)?
(a) How many grams of Zn3As2 (s) are required to prepare 75.00 g of AsH3?
(b) Describe (include quantities) how you would prepare 350.0 mL of a 2.50 M HNO3 (aq) solution if
you were provided with 1500 mL of 6.00 M HNO3 (aq) (mol mass = 63.01 g/mol)
8.
6
Sodium Tellurite (Na2TeO3, mol. mass = 221.58 g/mol) can be prepared by the reaction of Tellurium
dioxide (TeO2, mol. mass = 159.6 g/mol) with sodium hydroxide, NaOH (mol. mass = 40.00 g/mol)
according the balanced chemical reaction below
TeO2 (s)
+
2 NaOH (aq)

Na2TeO3
+
H2O (l)
(a)
If 46.00 g TeO2 is reacted with 150.0 mL of 0.85 M NaOH. How many grams of Na2TeO3 will be
produced? (for full credit you must show all work)
(b)
The only 38.5 g of Na2TeO3 was isolated from the reaction, what is the percent yield for this reaction.
.................... nothing left to do but smile, smile, smile
7
Useful Constants and Equations
h = 6.626 x 10-34 J•s
Planck's constant
c = 2.9979 x 108 m/s
6.022 x 1023
amu = 1.66054 x 10-27 kg
k = 1.38066 x 10-23 J / K
R = 8.31451 J / K mol
R = 0.08206 L • atm / K mol
1 atm = 760 torr = 760 mmHg
Speed of light
Avogadro’s number
Atomic mass unit
Boltzmann constant
Gas Constant
E = 2.31 x 10-19 J • nm (q1 q2 / r)
zero order:
[A] = -kt + [A]0; t1/2 = [A]0/2k
(KE)avg = 3/2 RT
first order:
ln [A] = -kt + ln [A]0; t1/2 = ln 2/k
urms = (3RT / M.wt.)1/2
second order: [A]-1 = kt + [A]-1; t1/2 = 1/k[A]0
ln(P1/P2) = H/R (1/T2 – 1/T1)
k = Ae-Ea/RT
ln(k1/k2) = Ea/R (1/T2 – 1/T1)
-b ± b2 - 4ac
x=
2a
E = mc2
E = h
 = c
P (MM) = dRT
Hydroxide
Cyanide
Common Ion Names
Ammonium
Carbide
Phosphate
Phosphite
Phosphide
Sulfite
Sulfate
Perchlorate
Hypochlorite
Chlorite
Chlorate
Chloride
Nitride
Nirate
Nitrite
Carbonate
Common Polyatomic Ions
-
NO2
NO3SO32SO42-
CO32CNPO43OH-
ClOClO2ClO3ClO4-
Sulfide
8
Solubility Rules for Ionic Compounds in Aqueous Solutions
A. Always Soluble Ions
NO3ClO4NH4+
Group 1 ions: Li+, Na+, K+, Rb+, Cs+
B. Insoluble Ions
Pb2+
CO32-
S2-
PO43-
CrO42C. Generally Soluble Ions
Cl-, Br-, I- (insoluble with Ag+, Pb2+)
SO42- (insoluble with Ba2+, Ca2+, Sr2+, Pb2+)
OH- only soluble with Group I or II ions (insoluble with other metal ions)
Strong Acid List for Aqueous Solution
HCl
HBr
HI
HNO3
HClO3
HClO4
H2SO4