Dr. Bolaños
CHEM 110 - Exam 2
Fall 2015
Name:____________________________________________ Student #:______________________________
PLEASE TEAR OFF THE SCRATCH SHEE AT THE END OF THIS EXAM and sign the Honor Code below. Please read over
the entire exam before you begin, in order to maximize your earned points. There are 21 questions on this examination
totaling 103 points (scored out of 100 pts; point values are clearly stated on problems). You have 2.5 hours to complete this
examination and may only use a basic scientific calculator and provided Periodic Table. All work must be shown for credit (no
work needed for multiple choice or fill-in questions, no partial credit). Clearly write your name of the scratch sheet of paper and
submit at the end of the examination period. If you need additional scratch paper or further clarification, please raise your hand.
Good Luck! **I certify the work below is my own. I did not give nor receive any assistance and I followed all rules setforth.
Signature_____________________________________________________
Questions 1-11:
Please provide the best response for each; no partial credit. (1.5 pts each unless otherwise
stated; 22.5 pts total).
1. The oxidation number of bromine in BrO2- is ___________.
2. The concentration of nitrogen dioxide was determined for a
system on two sequential days. The day that has the higher
concentration is ____________________.
3.
Day 1
Day 2
Concentration Nitrogen Dioxide
2.500 ppm
250.0 ppb
A student adds 0.675 moles of NaCl to a total solution volume of 100.0 mL. The molarity of NaCl solution is
____________________________.
4. The coefficient in front of the second reactant is _______________, when the reaction below is balanced.
__Al (s) + ___ S8 (s)
___ Al2S3
5. The "type of reaction" in Q4, above is ___________________________ (besides REDOX!). The substance
that gains electrons is ____________, the substance that is reduced is _____________. (3 pts total, 1 pt ea)
6. A student is asked to prepare 500.0 mL of a 1.200 M NaCl solution. The student needs to add
___________________ g NaCl. The molar mass of NaCl is 58.5 g/mol. Watch SF! (3 pts)
7. Translate into a BALANCED chemical reaction with phase labels (3 pts) :
gaseous ammonia (NH3) reacts with gaseous oxygen to form gaseous nitrogen monoxide and water vapor.
________
+
________
________
+
________
8. The generic formula for alkynes is ______________, while the empirical formula of C4H10 is ______________.
9. The mixing of sodium sulfate and copper (II) nitrate results in a ______________________________reaction.
(Possible fill-in choices: decomposition, combination, single replacement, double replacement, no reaction.). Be
careful!
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Dr. Bolaños
CHEM 110 - Exam 2
Fall 2015
10. A metal that could be used to precipitate calcium ions (as Ca solid) from a solution is: _____________.
11. Of the substances below, which are soluble in water? Letters ____________________.
a. HC2H3O2
b. ZnS
c. Al(OH)3
d. CH3CH2OH (ethanol)
12. A 2.00 L aqueous solution of 0.350 M ethanol is desired. The available stock solution is 3.50 M Ethanol.
__________mL of stock ethanol solution will ultimately be mixed with water to the 2.00 L mark in this type of
flask ________________________________. (3 pts total; 2 pts first blank, 1 pt last blank)
13. For the following, provide a balanced NET ionic reaction. (5 pts)
NaOH (aq) + CuSO4 (aq)
14. What is the concentration in ppm of copper(II) nitrate, when 3.999 g of copper(II) nitrate (FW 187.56) is mixed
with water to a total solution volume of 500.0 mL? The density of water at the lab temperature is 1.001 g/mL
and the density of the solution is 1.099 g/mL. (5 pts)
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Dr. Bolaños
CHEM 110 - Exam 2
Fall 2015
15. Please fill-in the table with the appropriate response. Spelling counts! (13.5 pts total, 1.5 pts total)
Chemical Formula
Chemical Name
Ammonium hydrogen carbonate
CaSO4 * 2 H2O
Iodous acid
Zn3N2
Ca(ClO4)2
P2S3
Cobalt(I) dichromate
H2S (aq)
3-heptene
16. A solution containing HBr has a density of 1.40 g/mL and a molarity of 16.8 M. What is the weight percent of
of HBr in the solution? The molar mass of HBr is 80.9120 g/mol. All work must be shown for credit. (6 pts)
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Dr. Bolaños
CHEM 110 - Exam 2
Fall 2015
17. Please provide the appropriate information below. (8 pts total; 4 pts each)
Compound Name
Structure (“sticks” or condensed structure)
18. A solution is prepared by mixing 0.10 L of 0.15 M NaCl with 0.25 L of 0.18 M MgCl2.. Water is then added and
the final solution volume is 500.0 mL . What is the molarity of the chloride ions in this 500.0 mL solution? (6
pts)
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Dr. Bolaños
CHEM 110 - Exam 2
Fall 2015
19. Please answer each of the following with the appropriate response. (14 pts total, 3.5 pts each)
Balanced RXN with predicted products AND phases labels
Do your best with last one…remember: simplest products are favored! If no reaction, please state NR.
Assume transition metals are 2+ as ions.
C6H14 O3(g)
Fe (s)
+
+
(NH4)2CO3 (aq)
O2 (g)
H3PO4 (aq)
+
H3PO4 (aq)
KBrO3 (s) + Heat
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Dr. Bolaños
CHEM 110 - Exam 2
Fall 2015
20. Combustion analysis of a 13.42 g sample of equilin (contains only C, H, O) produces 39.61 g of carbon dioxide
and 9.01 g of water. What is the empirical formula of equilin? (10 pts)
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Dr. Bolaños
CHEM 110 - Exam 2
Fall 2015
21. For the reaction below, when 28.6 kg of C reacts with 88.2 kg of TiO2, 42.8 kg of Ti is produced.
TiO2 (s)
+
2 C (s)
Ti (s)
+
2 CO (g)
a. What is the percent yield of Ti, in grams? Show all work for credit. (6 pts)
b. How many grams of excess reactant is consumed ? Be careful here, please! (4 pts)
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Dr. Bolaños
CHEM 110 - Exam 2
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Fall 2015
Dr. Bolaños
Resource Sheet
CHEM 110 - Exam 2
Fall 2015
Name_______________________________
9
Dr. Bolaños
Scratch Paper
CHEM 110 - Exam 2
Fall 2015
Name_______________________________
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