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CHEM 1031 – PRACTICE EXAM I – FALL 2017
(You will need a periodic table. Answers are on page 4.)
1. ___ At room temperature, nitrogen gas is the least reactive of the elemental diatomic gases. This
statement is best described as a:
A. theory
B. qualitative observation
C. law
D. quantitative observation
2. ___ The bonding within the nitrogen molecule is:
A. covalent
B. ionic
C. metallic
D. no bonding; nitrogen is an element
Lithium batteries are used in cell phones partly because of their high voltage/weight ratio. However,
the extreme reactivity of lithium makes manufacture of these batteries a challenge. As an example,
lithium will react with nitrogen at room temperature.
3. ___ The bonding within this lithium nitrogen compound is:
A. covalent
B. ionic
C. metallic
4. ___ Select the formula for this lithium nitrogen compound:
A. LiN
B. Li3N
C. Li2N
D. impossible to predict
5. ___ Select the correct name for this lithium nitrogen compound
A. trilithium nitride
B. lithium(I) nitride
C. lithium nitride
D. lithium nitrate
6. ___ Many of you learned in lab that a vernier caliper can be read in cm to 3 decimal places. A
measurement of 0.030 cm contains ______ significant figures.
A. 1
B. 2
C. 3
D. 4
7. ___ Air is an example of a(n)
A. element
B. compound
C. heterogeneous mixture
D. homogeneous mixture
8. ___ The number of protons, neutrons, and electrons in the ion formed by
A. 13, 27, 13
B. 13, 14, 10
C. 10, 14, 10
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Al are, respectively:
D. 13, 27, 10
9. ___ Select the subatomic particle(s) found in the nucleus of an atom.
A. proton
B. proton, electron C. neutron
D. proton, neutron E. proton, neutron, electron
10. ___ Ammonium nitrate is a(n) _____ compound.
A. covalent compound
B. ionic compound C. heterogeneous mixture D. homogeneous mixture
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11. ___ N2O5 is a(n) ____ compound and is named _____.
A. ionic, dinitrogen pentoxide
C. molecular, nitrogen (V) oxide
B. ionic, nitrogen (V) oxide
D. molecular, dinitrogen pentoxide
12. ___ H3PO4(aq) is best described as a(n):
A. compound
B. heterogeneous mixture
C. homogeneous mixture
D. none of these
13. ___ H3PO4(aq) is named:
A. trihydrogen phosphate
C. phosphoric acid
B. trihydrogen phosphite
D. hydrogen phosphate
14. ___ The formula for the compound formed between barium and carbonate ions is:
A. BaCO3
B. Ba2(CO3)3
C. BaC
D. BaPO4
15. ___ The name of the compound in question 14 is:
A. barium(I) carbonate
C. barium carbonate
B. barium(III) carbonate
D. dibarium tricarbonate
16. ___ Chromium forms several oxides, including Cr2O3 and CrO3. The name for Cr2O3 is:
A. dichromium trioxide
B. chromium oxide
C. chromium(III) oxide
D. none of these
17. ___ Which state of matter maintains its own shape in a closed container?
A. solid
B. liquid
C. gas
18. ___ When Mendeleev proposed the periodic table, he predicted the existence and properties of
several undiscovered elements. New experiments confirmed the existence of these elements. The
periodic table became an important ____ of chemistry.
A. observation
B. law
C. theory
19. ___ Antimony (Z = 51) has 2 stable isotopes, 121Sb (120.904 amu) and 123Sb (122.904 amu).
Calculate the % abundance of 121Sb.
A. 33.35 %
B. 57.70 %
C. 73.42 %
D. 50.00 %
20. ___ The most numerous type of elements in the periodic table are:
A. metal
B. nonmetal
C. metalloid
D. polyatomic
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For each of the calculations below, give your answers to the correct number of significant figures,
and in scientific notation if appropriate.
21. The average speed of a helium atom at room temperature is 1255. m/s. Convert this speed to
miles/hour. (2.54 cm = 1 inch, 5,280 ft = 1 mile, 12 inch = 1 ft)
22. A sheet of aluminum (density = 2.70 g/cm3) has an area of 1.000 ft2 and a mass of 3.636 g.
Calculate the thickness of the foil in m. (2.54 cm = 1 inch, 12 inches = 1 ft)
23. Calculate (a) the number of oxygen atoms present in 5.00 g copper(II) sulfate pentahydrate, and
(b) the mass of hydrogen in 5.00 g copper(II) sulfate pentahydrate.
24. A sample of aluminum was burned in an excess of oxygen, producing 10.0 g of aluminum oxide,
which represents a 92.5 % yield. (a) Write a balanced chemical equation for this reaction,
(b) calculate the theoretical yield, in grams, of aluminum oxide, and (c) assuming that aluminum is the
limiting reactant, calculate the mass, in grams, of aluminum that was used in the reaction.
25. An unknown compound contains 51.97% C, 5.23% H, 12.12% N, and 30.68% Cl and has a molar
mass of approximately 347 g/mol. (a) Determine the empirical formula of the unknown compound.
(b) What is the chemical formula of the compound? (c) The mass of the unknown compound that
contains 2.6 x 1022 chlorine atoms. (Nav = 6.022 x 1023 mol–1)
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ANSWERS
1. B
2. A
3. B
4. B
5. C
6. B
7. D
8. B
9. D
10. B
11. D
12. C
13. C
14. A
15. C
16. C
17. A
18. B
19. B
20. A
21. 2.81 x 103 m/s
22. 14.5 m
23. (a) 1.09 x 1023 atoms
(b) 0.202 g
24. (a) 4 Al(s) + O2(g) → 2 Al2O3(s)
(b) 10.8 g
(c) 5.72 g
25. (a) C5H6NCl
(b) C15H18N3Cl3
(c) 5.0 g