Camosun College
Chemistry 110 Midterm Exam 1
Name _____________________
Instructor: Larry Lee
Student ID__________________
Total Marks_________________
Instructions: This exam is a 2 hour closed book exam. A periodic table is provided and only a scientific
calculator is allowed. Please write your answers in the space provided. If more room is required please
write on the back page of the paper. This exam has 8 pages including the periodic table, data sheet, and
the cover page.
Total marks = 60 marks
Total time = 120 minutes
CHEMISTRY 110
Midterm Exam 1
October 4, 2007
1
Chemistry 110 Midterm Exam 1
[12] 1. Answer the following questions in the space provided
60 marks
a. The number of neutrons in an atom of 140Ba is _______________
b. The number of electrons in an ion of Mn2+ is __________________
c. The number of protons in the 3H (tritium isotope)___________________
d. An example of a Group 13 element is __________________
e. An acceptable name for Ba3P2 is_________________________
f. An acceptable name for PBr5 is___________________________
g. An acceptable name for NaCH3CO2 is____________________________
h. The molecular formula for Aluminum nitrate is ______________________
i. The molecular formula for Barium carbonate is________________________
j. The oxidation number of Br in Ca(BrO3)2 is ____________________
k. The oxidation number of N in NO3Ө is ____________________
l. The atom or ion that is isoelectronic with calcium ion (Ca2+) is _______________
m. The electron configuration for a hypothetical P2- (-2 charge on P) is _______________
[6]
2.
Write a balanced equation for the reaction of a solution of magnesium nitrate that reacts
with a solution of sodium hydroxide to precipitate magnesium hydroxide and to give a
solution of sodium nitrate. Do not forget the physical states (ie, solid (s), liquid (l), gas
(g), or aqueous (aq) of each reagent.
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Chemistry 110 Midterm Exam 1
[4]
3.
Perform the following conversions with the correct number of significant figures (show
calculations).
a) 3.56 in3 to feet3
note: 12 inches = 1 foot
b) 22.5 mile/hour to meter/second: note: 1 mile = 1.609 km; 1 hour = 3600 sec .
[6]
4.
For the redox reactions shown below, indicate in the space provided, the oxidizing agent, the
reducing agent, the species and element being oxidized, the species and element being
reduced
FeO(s) + CO(g)
heat
→ Fe (l) + CO2 (g)
Oxidizing agent ____________
Reducing agent ____________
Species oxidized ___________
Species reduced ____________
Element oxidized _____________
Element reduced ______________
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Chemistry 110 Midterm Exam 1
[8]
5.
Balance the following redox reactions in base by using the half reaction method and answer
the questions in the space provided.
Cl2 (g) + S2O32- (aq) → Cl1-(aq) + SO42- (aq)
What species is the reducing agent? _________________
What species is the oxidizing agent? __________________
[8]
6.
Balance the following redox reactions in acid by using the half reaction method and answer
the questions in the space provided.
H2O (l) + Cr2O72-(aq) →
O2 (g) + Cr3+(aq)
What species is the reducing agent? _________________
What species is the oxidizing agent? __________________
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Chemistry 110 Midterm Exam 1
[10] 7.
Diborane (B2H6) is a colourless gas with a repulsively sweet odour. It has been used in
rocket propellants. Diborane can be prepared by the following reaction:
3NaBH4 (s)
+ 4BF3(g)
3NaBH4 (s)
→ 2B2H6(g) +
+
4BF3(g)
3NaBF4(s)
→
2B2H6(g)
3NaBF4(s)
Molar mass
Gram
Mol available
Mol needed
Answer the questions below, given the following information:
A student reacted 15.6 grams of NaBH4 with 20.2 grams of BF3 and produced the diborane
(B2H6) in 25.5 % yield.
a) Complete the table shown above. Show calculation only for the mole of BF3(g) required to
react with all NaBH4(s)
a) Which is the limiting reagent?
b) Calculate the grams of excess reagent. Show calculations
5
Chemistry 110 Midterm Exam 1
c) Calculate the theoretical yield of NaBF4 product. Show calculations
d) How many grams of diborane was obtained experimentally at 25.5% yield?
calculations
[6]
Show
8. Give the products for the following double displacement reactions. Indicate the physical state
of the products. Balance the equation (Assume sodium, potassium, and nitrate salts are soluble
and everything else is insoluble) If water is produced then that is a liquid.
a. ____Mg(NO3)2 (aq)
+ ____NaOH(aq) → ___________________________________
b. ____Na3PO4(aq) +
____PbCl2(aq)
c. ____Ba(NO3)2(aq)
+ ____Na2SO4(aq) →__________________________________
→____________________________________
End of exam
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