Download FINAL EXAM, CHE 101, SUMMER 2007 (200 PTS)

Name ________________________________
NSCC, Summer 2007
FINAL EXAM, CHE 101, SUMMER 2007 (200 PTS)
Part A. Chapters 1 - 4, and 9
1. Classify each of the following elements as a metal, nonmetal, or metalloid
a.
b.
c.
d.
e.
Carbon
Chromium
Silicon
Nonmetal
Metalloid
Metal
Nonmetal
Metalloid
Metalloid
Metal
Nonmetal
Metal
Metal
Metal
Nonmetal
Metalloid
Metalloid
Metalloid
2. In one of your laboratory experiments you used the concept of water displacement to figure out
the mass of an object. If you placed a ceramic object, with a density of 2.084 g/mL, in a graduated
cylinder containing 60.0 mL of water and the water level rose to 92.6 mL, what is the mass of the
object?
a. 15.6 g
b. 44.4 g
c. 67.9 g
d. 3.22 g
e. 73.2 g
3. What is the mass number of an ion with 29 protons, 36 neutrons, and 27 electrons?
a. 65
b. 36
c. 56
d. 92
e. 29
4. What is the electron configuration of vanadium (V, atomic number 23)
a. 1s22s22p63s23p64s23d5
b. [Ne] 4s33d3
c. [Ar] 4s23d3
d. [Ar] 4s03d5
e. [Ne] 4s03d5
5. What is the product of -emission in the following reaction?
126
50
a.
126
51
Sn
b.
126
50
Sn
?

Sn
0
+
c.
1
-1
e
126
49
In
d.
126
51
Sb
Name ________________________________
NSCC, Summer 2007
Problem Solving: Chapters 1 – 4, and 9
6. Assume that at certain temperature, the equilibrium constant (Kc) equals 5.8 x 10-7 for the
following balanced reaction
O2 (g) + O (g)  O3 (g)
How many grams of O3 (g) were produced if the initial concentration of both reactants was 1 x 102 M
and the final volume of the reaction is 1.0 L? [Hint, figure out moles of product first].
7. As we learned in class, in covalent compounds atoms tend to share electrons, which form covalent
bonds, in order to achieve an octet. We used electron dot formulas to illustrate which valence
electrons are shared and which are lone pairs.
a. Below is the structure of acetyl chloride, drawn with bonds and electron dots. Determine
how many bonding electrons and lone pairs are shown.
# of bonding electrons: __________
# of lone pairs: ________________
b. Write the formula for sulfur dioxide and show its electron dot structure
Formula:
Electron dot structure:
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Name ________________________________
NSCC, Summer 2007
Part B. Chapters 5, 6, and 8
8. How many grams are there in 0.500 moles of sodium chloride?
a. 14.61 g
b. 7.306 g
c. 29.23 g
d. 58.46 g
e. 0.500 g
9. How many moles of oxygen will form when 5.0 moles of lead oxide react (reaction is shown
below)?
2 PbO(s) → 2 Pb(s) + O2(g)
a.
b.
c.
d.
e.
5.00 moles
2.50 moles
10.0 moles
80.0 moles
54.5 moles
10. The heat of fusion for water is 80 cal/g, heat of vaporization is 540 cal/g, and specific heat is
1cal/g oC. How many calories are required to convert 25.5 g of ice at oC to steam at 100 oC?
a.
b.
c.
d.
e.
18360 calories
91800 calories
16320 calories
2550 calories
15810 calories
11. What is the molarity of a solution containing 60.0 grams of KCl in 0.500 L of solution?
a. 120.0 M
b. 0.00833 M
c. 1.61 M
d. 0.621 M
e. 34.5 M
12. Barium phosphate is formed from the reaction of barium chloride and sodium phosphate as shown
in the balanced equation below. What mass of barium phosphate is produced by the reaction of
200.0 mL of 0.1200 M solution of barium chloride with excess sodium phosphate?
3BaCl2 + 2Na3PO4  Ba3(PO4)2 + 6NaCl
a.
b.
c.
d.
e.
0.004 g
14.42 g
4.808 g
0.234 g
5.345 g
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Name ________________________________
NSCC, Summer 2007
Problem Solving: Chapters 5, 6, and 8
13. Aspartame is an artificial sweetener that is 160 times sweeter than sucrose (table sugar) when
dissolved in water. It is marketed as Nutra-Sweet. The molecular formula of aspartame is
C14H18N2O5
a. Calculate the molar mass of aspartame
b. How many moles are in 10.0 g aspartame?
c. How many molecules are in 5.0 g aspartame?
14. Nitrogen gas can be prepared by passing gaseous ammonia (NH3) over solid copper (II) oxide at
high temperatures. The other products of the reaction, in addition to nitrogen gas, are solid copper
and water vapor, H2O(g). A sample containing 18.1 g of NH3 is reacted with 90.4 g of CuO to
give the above products.
a. Write balanced equation for this reaction (note all the formulas are given above).
b. Which is the limiting reactant, NH3 or CuO?
c. How many grams of N2 will be formed?
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Name ________________________________
NSCC, Summer 2007
Part C. Chapters 7 and 10
15. What is the pH of a solution with [H3O+] = 1.0 x 10-4
a. –4.00
b. 2.50
c. 4.00
d. 1.0 x 10-2
e. – 2.50
16. What is the concentration of [OH-] in a solution with pH of 4.5
a. 3.16 x 10–5
b. 4.50
c. 3.16 x 10–10
d. 1.00 x 10–14
e. 7.00
17. How many milliliters of 0.30 M NaOH are required to completely neutralize 25.0 mL of 0.40 M
HCl?
a. 25.0 mL
b. 18.8 mL
c. 33.3 mL
d. 4.80 mL
e. 12.5 mL
18. A small balloon has a volume of 0.50 L at a temperature of 10 °C. What is the new volume of the
balloon when the temperature rises to 25 °C and the pressure remains constant?
a. 0.53 L
b. 0.47 L
c. 1.3 L
d. 1.0 L
e. 2.0 L
19. What is the molar mass of a piece of metal with a mass of 8.50 g if it has a volume of 2.0 L at 25
o
C and pressure of 1.0 atm? [R = 0.0821 atm.L/mol.K]
a. 0.0817 g/mole
b. 103.98 g/mole
c. 0.0096 g/mole
d. 0.9744 g/mole
e. 8.7231 g/mole
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Name ________________________________
NSCC, Summer 2007
Problem Solving: Chapters 7 and 10
20. We learned the concept of acid strength. We said that acids are classified as strong or weak.
Strong acids dissociate nearly completely in water whereas weak acids dissociate only slightly.
We said that the acid dissociation constant, Ka, is a measure of acid strength for weak acids
[Recall there are six strong acids]. Lets apply this concept to proteins.
Proteins are complex biological molecules made of smaller molecules called amino acids. Five
common amino acids and their Ka values are listed below. Rank them from strongest to weakest
acid.
Amino Acid
glutamine 6×10−3
arginine
2×10−2
threonine 3×10−3
tryptophan
proline
4×10−3
1×10−2
[If it helps you, convert the scientific notation to standard format, for instance 1 x 10–2 = 0.01]
Strongest: _____________
______________
_____________ ____________
____________ Weakest
Extra Credit (10 pts)
21. A volume of 18.0 L contains a mixture of 0.250 moles N2, 0.25 moles O2, and an unknown
quantity of He. The temperature of the mixture is 0 oC, and the total pressure is 1.00 atm. How
many grams of helium are present in the gas mixture? [Hint, use the ideal gas law to figure out the
total moles of the gas, and work your way from there on].
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