Modified True/False
Indicate
whether the sentence or statement is true or false. If false, change the identified word or
phrase to make the sentence or statement true.
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1.
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In a
balanced chemical equation, the total mass of reactants equals the total mass of products.
____________________
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2.
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One
mole of NH3(g) molecules contains one mole of nitrogen atoms and three moles of
hydrogen atoms. ____________________
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3.
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One
mole of CO2(g) molecules contains 6.02 ´ 1023 CO2(g) molecules.
____________________
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4.
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The
atomic mass unit is equal to the mass of 12 carbon-12 atoms.
____________________
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5.
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The
isotopes of an element differ by the number of protons in the nucleus.
____________________
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6.
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If
the atomic mass of chlorine is 35.5 u/atom, the molar mass of chlorine is
35.5 g/mol. ____________________
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7.
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Molecular elements contain two or more atoms of the same element.
____________________
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8.
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The
law of constant composition states that compounds contain atoms in fixed proportions.
____________________
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9.
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A
combustion analyzer measures the molar mass of a compound.
______________________________
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10.
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The
information provided by a combustion analyzer and mass spectrometer may be used to determine the
molecular formula of a compound. ____________________
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11.
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If
the molecular formula of a compound is C3H8NS, then its empirical formula is
also C3H8NS. ____________________
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Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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12.
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What
amount of carbon dioxide is in 17.6 g of carbon dioxide? a. | 5.87
mol | c. | 0.40
mol | b. | 2.5
mol | d. | 0.55
mol | | | | |
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13.
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The
molar mass of methanol, CH4O(l), is a. | 28.0
g/mol | c. | 29.0
g/mol | b. | 31.0 g/mol | d. | 32.0 g/mol | | | | |
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14.
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The
molar mass of calcium phosphate, Ca3(PO4)2(s), is a. | 278
g/mol | c. | 247
g/mol | b. | 310 g/mol | d. | 199 g/mol | | | | |
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15.
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The
mass of 3.75 mol of KF(s) is a. | 3.75 g | c. | 217.8 g | b. | 58.1
g | d. | 108.9
g | | | | |
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16.
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What
amount of iron is in 5.00 mol of FeO(s)? a. | 5.00
mol | c. | 1.00
mol | b. | 10.00
mol | d. | 2.50
mol | | | | |
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17.
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How
many molecules of NO(g) are in 16.0 g of NO(g)? a. | 3.21
´
1023 | c. | 1.81
´
1025 | b. | 9.63 ´ 1024 | d. | 6.02 ´ 1023 | | | | |
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18.
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Which
of the following elements contains the greatest number of atoms in a 5.00-g sample? a. | lithium | c. | potassium | b. | sodium | d. | rubidium | | | | |
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19.
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Which
of the following samples contains the same number of atoms as 40.00 g of
Ne(g)? a. | 4.00 g of
He(g) | c. | 40.00 g of
C(s) | b. | 24.00 g of Mg(g) | d. | 80.00 g of Ar(g) | | | | |
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20.
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How
many molecules are in 0.25 mol O2(g)? a. | 12 ´ 1023 | c. | 3.0 ´ 1023 | b. | 6.0 ´
1023 | d. | 1.5 ´
1023 | | | | |
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21.
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What
is the mass of iron in 1.00 mol Fe2O3(s)? a. | 160
g | c. | 72.0
g | b. | 112
g | d. | 56.0
g | | | | |
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22.
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How
many oxygen atoms are in 49.0 g of H2SO4(aq)? a. | 2.4 ´
1024 | c. | 3.01
´
1023 | b. | 6.02 ´ 1023 | d. | 1.2 ´ 1024 | | | | |
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23.
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Which
of the following statements is incorrect? a. | One mole of ozone has a mass of 48.0
g. | b. | One mole of
methane, CH4(g), contains 6.02 ´ 1023 carbon atoms. | c. | 12.01 g of
carbon has the same number of atoms as 12.01 g of nitrogen. | d. | One mole of a
substance is the amount of the substance that has the same number of entities as 12.00 g of
carbon-12. | | |
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24.
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Which
of the following entities has the greatest mass? a. | one atom of aluminum | c. | one atom of phosphorus | b. | one molecule of
fluorine | d. | one molecule of
methane | | | | |
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25.
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A
mass spectrometer measures a. | the percentage of elements in a
compound | b. | the molar mass of a compound | c. | the number of
ions in an ionic compound | d. | the charge on an ion | | |
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26.
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The
empirical formula of a compound is CH. Its molar mass is 78.0 g/mol. What is its molecular
formula?
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27.
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The
percentage composition by mass of a compound is 52.16% carbon, 7.29% hydrogen, and 40.55% nitrogen.
Its molar mass is 138.20 g/mol. What is the molecular formula of the compound? a. | C8H14N2 | c. | C6H10N4 | b. | C7H12N3 | d. | C3H5N2 | | | | |
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28.
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What
is the percentage by mass of chlorine in hypochlorous acid, HClO(aq)? a. | 46.71% | c. | 30.52% | b. | 23.40% | d. | 67.58% | | | | |
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29.
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What
is the percentage by mass of nitrogen in Cu(NO3)2(s)? a. | 14.93% | c. | 50.61% | b. | 33.88% | d. | 44.40% | | | | |
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Completion
Complete each sentence or
statement.
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30.
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The
number 6.02 ´ 1023 is equivalent to ____________________
constant.
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31.
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The
term ____________________ specifically refers to the number of moles of chemical entities in a
quantity of matter.
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32.
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When
working with chemical entities, the mole is a reasonable quantity because this quantity can be
____________________ and ____________________.
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33.
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The
____________________ number of an element is equal to the number of protons in the
nucleus.
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34.
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The
atomic molar mass of an element is equal to the mass, in grams, of one ____________________ of atoms
of the element.
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35.
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Chemists determine the amount of a chemical entity in a pure sample by measuring the
____________________ of the sample.
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36.
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The
empirical formula of a compound describes the ____________________ ratio of atoms or ions in a
compound
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