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. |
The
empirical formula of a compound is the formula that yields the simplest
ratio between the atoms of the elements in the compound. ______________________________
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2. |
The
formula for carbon tetrachloride, CCl4, is both an empirical
formula and a molecular formula. ______________________________
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3. |
If
the percentage, by mass, of nitrogen in ammonia, NH3, is 82.4%, then
100 g of ammonia contains 17.6 g of hydrogen. ____________________
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4. |
The
SI unit for molar mass is g/mol, and the SI symbol for molar mass is
mm. ____________________
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5. |
A
mass spectrometer is a device for determining the relative masses
of individual atoms. ____________________
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6. |
One
mole of carbon dioxide contains 6.02 ´ 1023 molecules of carbon dioxide.
____________________
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7. |
The
molar mass of ammonia, NH3(g), is 56.34 g/mol. ____________________
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8. |
If
the molar mass of an ionic compound is 18.04 g/mol, then 18.04
g of the compound contains 6.02 × 1023 formula units.
____________________
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9. |
The
amount of molecules in 71.6 g of methane, CH4 (molar mass
= 16.0 g/mol), is 4.48 mol. ____________________
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10. |
The
amount of excess reagent determines the amount of product that
is formed in a chemical reaction. ____________________
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11. |
In
any chemical reaction, the theoretical yield will be less than
or equal to the actual yield. ____________________
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12. |
If
165.0 g of silver iodide is produced in a reaction for which the theoretical
yield is 192.0 g, the percentage yield is 85.94%. ____________________
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13. |
The
following equation is balanced:
2
AgNO3 + CaCl2 ® 2 AgCl + Ca(NO3)2 ____________________
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14. |
If
0.50 mol potassium chloride, KCl(s), is dissolved in 1.0
L of water, the concentration of potassium chloride in the resulting
solution is 0.50 mol/L. ____________________
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15. |
Adding water to a solution increases the solution’s
concentration. ____________________
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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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16. |
The
law of constant composition states that
a. |
substances can be made up of only one type
of element |
b. |
compounds always contain carbon and hydrogen |
c. |
a compound contains elements in certain
fixed proportions, regardless of how the compound is prepared
or where it is found in nature |
d. |
the
proportions of elements in a compound can change as long as the
molar mass of each element remains the same |
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17. |
One
atomic mass unit is defined as
a. |
exactly 
the mass of a carbon-12 atom |
b. |
exactly
14 times the mass of a carbon-12 atom |
c. |
exactly 
the mass of a carbon-12 atom |
d. |
exactly
12 times the mass of a carbon-12 atom |
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18. |
The
SI unit for the atomic mass unit is
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19. |
Chlorine has two naturally occurring isotopes, 
and  . The composition of chlorine is 25.0% 
and 75.0%  .
The relative atomic mass of chlorine is
a. |
36.5 u |
c. |
34.6 u |
b. |
35.5
u |
d. |
45.5
u |
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20. |
The
number of carbon atoms in 0.062 mol acetic acid, HC2H3O2(aq),
is
a. |
7.5
´
1022 atoms |
c. |
1.5
´
1023 atoms |
b. |
3.8 ´ 1022 atoms |
d. |
6.0 ´ 1023 atoms |
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21. |
If
the molar mass of a compound is 98.2 g/mol, the mass of 6.3 mol
of the compound is
a. |
15.6
g |
c. |
102.3
g |
b. |
6.4
´
10–2 g |
d. |
6.2
´
102 g |
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22. |
The
amount of sodium phosphate, Na3PO4, in 2.20
g of sodium phosphate is
a. |
7.45
mol |
c. |
1.34
´
10–2 mol |
b. |
74.5 mol |
d. |
13.4 mol |
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23. |
A
patient takes two pills, each containing 50.0-mg of a drug, on a daily
basis to help regulate a heart condition. If the amount of the drug
in each pill is 2.5 ´ 10–4 mol, then the drug’s
molar mass is
a. |
200
g/mol |
c. |
400
g/mol |
b. |
100 g/mol |
d. |
50 g/mol |
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24. |
The
percentage composition of chlorine, by mass, in the compound K2PtCl4
is
a. |
47.0% |
c. |
18.9% |
b. |
34.2% |
d. |
15.3% |
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25. |
The
percentage composition by mass of each element in sodium sulfate, Na2SO4,
is
a. |
32.4%
Na, 22.6% S, 45.0% O |
c. |
43.7%
Na, 20.7% S, 35.6% O |
b. |
22.6% Na, 32.4% S, 45.0% O |
d. |
20.7% Na, 43.7% S, 35.6% O |
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26. |
A
100.0-g sample of a compound contains 26.6 g of potassium, 35.4 g of
chromium, and 38.0 g of oxygen. The empirical formula of the
compound is
a. |
KCrO5 |
c. |
K2Cr2O7 |
b. |
KCrO3 |
d. |
K3Cr3O10 |
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27. |
A
100.0-g sample of an organic compound is made up of 40.00 g of carbon,
6.71 g of hydrogen, and 53.29 g of oxygen. If its molar mass is 90.0
g/mol, its molecular formula is
a. |
CH2O |
c. |
C2H4O2 |
b. |
C3H6O3 |
d. |
C7H14O7 |
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28. |
Which
of the following scenarios does NOT represent a quantitative analysis?
a. |
A
chemist tests a sample of water for the presence of chloride ions. |
b. |
A
police officer uses a Breathalyzer to measure the amount of alcohol
in exhaled air. |
c. |
A
lifeguard tests a sample of water to see how much disinfectant
is present in the water. |
d. |
A sample of soil from a farm is tested for
dangerously high concentrations of pesticides. |
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29. |
If
226.1 g of tin(II) chloride is the actual yield obtained in a reaction
for which the theoretical yield is 288.0 g, the percentage yield is
a. |
71.15% |
c. |
81.98% |
b. |
78.51% |
d. |
84.11% |
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30. |
The
concentration of fluoride ions, F ,
in municipal drinking water cannot exceed 1.5-ppm. What is the maximum
mass of fluoride ions that can be dissolved in 250 mL of water?
a. |
0.38
mg |
c. |
750
mg |
b. |
1.5
mg |
d. |
0.003
mg |
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Completion
Complete each sentence
or statement.
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31. |
The
____________________ molar mass is the mass, in grams, of one mole of
atoms of a given element.
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32. |
Bromine, Br2, iodine, I2, and hydrogen, H2,
are examples of ____________________ elements.
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33. |
A(n)
____________________ analyzer may be used to determine the percentages
of carbon, hydrogen, oxygen, and nitrogen in a compound.
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34. |
To
determine the molecular formula of a compound, you need to know the
compound’s empirical formula and its ____________________.
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35. |
A(n)
____________________ solution always contains water as the solvent.
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36. |
____________________ is the process of decreasing the concentration
of a solution by adding more solvent.
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37. |
The
____________________ reagent is never completely consumed in a chemical
reaction.
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38. |
Side
reactions, reversible reactions, and impure reagents are all causes
of ____________________ yields in chemical reactions.
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