Download CHEM 1411. Chapter3. Mass Relations in Chemical Reactions

CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. There are two different common crystalline forms of carbondiamond and graphite. A less common form
called fullerene, C60, also exists. Different forms of the same element in the same physical state are called:
a. allotropes.
b. isotopes.
c. isomers.
d. structural formulas.
e. alloforms.
____
2. A compound contains only magnesium and oxygen. A sample of the compound is determined to contain 3.50 g
of magnesium and 2.30 g of oxygen. According to the Law of Definite Proportions, how much magnesium
should another sample of this compound contain if it contains 6.91 g of oxygen?
a. 10.5 g
b. 0.858 g
c. 55.5 g
d. 1.16 g
e. 4.54 g
____
3. What is the correct classification for OCl?
a. polyatomic molecule
b. monatomic cation
c. polyatomic cation
d. monatomic anion
e. polyatomic anion
____
4. Determine the number of sulfur atoms in 27.1 g of molecular sulfur (S8).
a. 2.07  1023
b. 5.27  1023
c. 5.09  1023
d. 0.106
e. 0.845
____
5. Calculate the formula weight of NaHSO4.
a. 185 amu
b. 104 amu
c. 193 amu
d. 215 amu
e. 120 amu
____
6. A 12.0-gram sample of Cr2(SO4)3 contains how many sulfur atoms?
a. 1.53  1021
b. 4.82  1021
c. 6.67  1022
d. 5.52  1022
e. 1.84  1022
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CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
____
7. Which of the following is not a correct description of 16.0 grams of methane, CH4?
a. It is the amount of methane that contains 4  6.02  1023 hydrogen atoms.
b. It is the amount of methane that contains 12.0 g of carbon.
c. It is the amount of methane that contains 4.0 grams of hydrogen.
d. It is one mole of methane.
e. It is 16.0  6.02  1023 molecules of methane.
____
8. What is the percent by mass of sulfur in Al2(SO4)3?
a. 18.8%
b. 35.4%
c. 9.38%
d. 28.1%
e. 24.6%
____
9. A 2.086-g sample of a compound contains 0.884 g of cobalt, 0.482 g of sulfur, and 0.720 g of oxygen. What is
its simplest formula?
a. Co(SO4)2
b. CoSO4
c. CoSO3
d. Co(SO3)2
e. Co3(SO4)4
____ 10. What is the empirical formula of an oxide of nitrogen that contains 36.84 % nitrogen by mass?
a. N2O
b. NO2
c. NO
d. N2O5
e. N2O3
____ 11. Which of the following samples contains the greatest number of atoms?
a. 90.00g Br
b. 7.25g Li
c. 73.21g Zn
d. 152.11g Cs e. 140.87g Sb
____ 12. How many atoms of chlorine are present in 2.42 grams of boron trichloride, BCl3?
a. 3.73 x 1022 atoms
b. 1.24 x 1022 atoms
c. 5.14 x 1026 atoms
d. 4.15 x 1021 atoms
e. 5.69 x 1025 atoms
____ 13. How many ammonia (NH3) molecules are there in a 115 g sample of ammonia?
a. 4.06 x 1024
b. 1.18 x 1027
c. 1.91 x 1022
d. 3.07 x 1020
e. 5.24 x 1021
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CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
____ 14. What are the empirical and molecular formulas for the following compound?
(C = dark atoms, H = light atoms)
a. CH (molecular) C6H6 (empirical)
b. CH2 (molecular) C6H12 (empirical)
c. C6H12 (molecular) CH2 (empirical)
d. C6H6 (molecular) CH (empirical)
____ 15. Which of the following is not a consequence of the Law of Conservation of Matter?
a. It can be stated as "matter is neither created nor destroyed during a chemical reaction."
b. It means that there will be no observable change in the quantity of matter during a chemical
reaction.
c. As a result, there will be the same number of moles on both the reactant and the product side
of a balanced equation.
d. It provides a basis for balancing chemical equations.
e. All of these are a consequence of the Law of Conservation of Mass.
____ 16. Balancing a chemical equation so that it obeys the law of conservation of matter requires:
a. Keeping the same number of molecules on both sides of the equation.
b. Making sure the reactants and products are in the same phase.
c. Keeping the total charge the same on both sides of the equation.
d. Adjusting the coefficients in front of the formulas so there are the same number and type of
atom on both sides of the equation.
e. Changing the formulas of the products and reactants.
____ 17. What is the coefficient for carbon dioxide when the following equation showing the combustion of isopropyl
alcohol is balanced with the smallest whole number coefficients?
C3H8O + O2  CO2 + H2O
a.
b.
c.
d.
e.
3
4
13
6
1
____ 18. What is the coefficient for HBr when the following equation is balanced with the smallest whole number
coefficients?
Br2 + H2O  HBr + HBrO3
a.
b.
c.
d.
7
8
6
3
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CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
e. 5
____ 19. Balance the following equation with the smallest whole number coefficients. Choose the answer that is the
sum of the coefficients in the balanced equation. Do not forget coefficients of "one".
Cr + H2SO4  Cr2(SO4)3 + H2
a.
b.
c.
d.
e.
15
13
7
11
9
____ 20. Balance the following equation with the smallest whole number coefficients. Choose the answer that is the
sum of the coefficients in the balanced equation. Do not forget coefficients of "one".
P4 + Cl2  PCl5
a.
b.
c.
d.
e.
15
7
9
13
11
____ 21. What is the sum of all coefficients when the following equation is balanced, using the smallest whole number
coefficients? Do not forget coefficients of "one".
Cl2O7 + Ca(OH)2  Ca(ClO4)2 + H2O
a.
b.
c.
d.
e.
8
6
5
4
10
____ 22. What is the sum of all coefficients when the following equation is balanced, using the smallest whole number
coefficients? Do not forget coefficients of "one".
SiCl4 + H2O  H4SiO4 + HCl
a.
b.
c.
d.
e.
12
6
10
14
8
____ 23. Consider the following balanced equation.
2H2 + O2  2H2O
Which one of the following statements is false?
a. The amount of reaction that consumes 32.0 g of O2 produces 36.0 g of H2O.
b. One molecule of O2 will react with 2 molecules of H2.
c. The complete reaction of 2.0 g of H2 will produce 36.0 g of H2O.
d. The complete reaction of 32.0 g of O2 will produce 2 moles of H2O.
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CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
e. One mole of O2 will react with 2 moles of H2.
____ 24. How many molecules of O2 would react with 56 C2H6 molecules according to the following balanced equation?
2C2H6 + 7O2  4CO2 + 6H2O
a.
b.
c.
d.
e.
112
50
784
196
392
____ 25. How many moles of O2 are required to react with 23.5 moles of methanol?
2CH3OH + 3O2  2CO2 + 4H2O
a.
b.
c.
d.
e.
35.3
47.0
23.5
40
11.8
____ 26. Propane (C3H8) burns in oxygen to form CO2 and H2O according to the following equation. How many grams of
O2 are required to burn 3.01  1023 propane molecules?
C3H8 + 5O2  3CO2 + 4H2O
a.
b.
c.
d.
e.
40.0 g
160 g
80.0 g
64.0 g
16.0 g
____ 27. Acrylonitrile, C3H3N, is a molecule used to produce a plastic called Orlon. How many grams of acrylonitrile
could be produced by reacting 583 g of propene, C3H6 with excess ammonia, NH3 and oxygen?
2C3H6 + 2NH3 + 3O2  2C3H3N + 6H2O
a.
b.
c.
d.
e.
368 g
735 g
1470 g
462 g
583 g
____ 28. What mass of SiF4 could be produced by the reaction of 15 g of SiO2 with an excess of
HF? The equation for the reaction is:
SiO2 + 4HF  SiF4 + 2H2O
a.
b.
c.
d.
e.
26 g
52 g
12 g
104 g
1.04 g
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CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
____ 29. What mass of Li3PO4 can be prepared from the complete reaction of 7.17 grams of LiOH with a stoichiometric
amount of H3PO4?
3LiOH + H3PO4  Li3PO4 + 3H2O
a.
b.
c.
d.
e.
9.61 g
11.6 g
9.34 g
10.4 g
9.80 g
____ 30. If a reaction of 5.0 g of hydrogen with 5.0 g of carbon monoxide produced 4.5 g of methanol, what was the
percent yield?
2H2 + CO  CH3OH
a.
b.
c.
d.
e.
63%
24%
96%
11%
79%
____ 31. What volume of 0.365 M NaOH solution contains 53.4 g NaOH?
a. 14.6 L
b. 2.05 L
c. 19.5 L
d. 146 L
e. 3.66 L
____ 32. The commercial production of phosphoric acid, H3PO4, can be represented by the equation
1540 g
296 g
310 g
Ca3(PO4)2 + 3SiO2 + 5C +
310 g/mol
60.1 g/mol 12.0 g/mol
1120 g
5O2 +
296 g
3H2O
32.0 g/mol
18.0 g/mol
 3CaSiO3 + 5CO2 + 2H3PO4
The molar mass for each reactant is shown below the reactant, and the mass of each reactant for this
problem is given above. Which substance is the limiting reactant?
a. H2O
b. SiO2
c. C
d. O2
e. Ca3(PO4)2
____ 33. The number of electrons in a neutral atom of an element is always equal to the ____ of the element.
a. Avogadro's number
b. atomic number
c. atomic mass unit
d. mass number
e. isotope number
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CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
____ 34. The atomic weight of silver is 107.868 amu. Naturally occurring silver consists of two isotopes: 107Ag (mass =
106.904 amu) and 109Ag (mass = 108.905 amu). What percentage of naturally occurring silver is the heavier
isotope?
a. 52.6%
b. 45.4%
c. 48.2%
d. 51.7%
e. 62.7%
____ 35. The element indium has two stable isotopes, indium-113 with an atomic mass of 112.9amu and
indium-115 with an atomic mass of 114.9amu. From the atomic weight found on the periodic table
for indium, one can conclude that:
a. Both isotopes have the same percent natural abundance
b. Indium-113 has the highest percent natural abundance
c. There is an isotope of indium with an atomic mass of 114.8amu
d. Indium-115 has the highest percent natural abundance
____ 36. Octane, C8H18, is a major component of gasoline. Write the balanced formula unit equation for the reaction of
the complete combustion of octane. What is the sum of the coefficients?
a. 49
b. 17
c. 30
d. 73
e. 61
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CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
Answer Section
MULTIPLE CHOICE
1. ANS: A
PTS: 1
OBJ: Define allotrope.
TOP: Chemical Formulas
2. ANS: A
PTS: 1
OBJ: Apply the Law of Definite Proportions.
TOP: Chemical Formulas
3. ANS: E
PTS: 1
OBJ: Classify a species as a monatomic ion, polyatomic ion, or molecule.
TOP: Ions and Ionic Compounds
4. ANS: C
PTS: 1
OBJ: Determine the molecular weight of a substance using atomic weights and the chemical formula. | Use
Avogadro's number, molecular formula, and molecular weight to convert grams to number of atoms.
TOP: The Mole
5. ANS: E
PTS: 1
OBJ: Determine the formula weight of a substance using atomic weights and the chemical formula.
TOP: Formula Weights, Molecular Weights, and Moles
6. ANS: D
PTS: 1
OBJ: Determine the formula weight of a substance using atomic weights and the chemical formula. | Use
Avogadro's number, molecular formula, and formula weight to convert grams to atoms.
TOP: Formula Weights, Molecular Weights, and Moles
7. ANS: E
PTS: 1
OBJ: Determine the molecular weight of a substance using atomic weights and the chemical formula.| Convert
grams of a substance to moles, grams of a component, molecules, or atoms.
TOP: Formula Weights, Molecular Weights, and Moles
8. ANS: D
PTS: 1
OBJ: Calculate percent mass of a component given the chemical formula of the substance.
TOP: Percent Composition and Formulas of Compounds
9. ANS: C
PTS: 1
OBJ: Derive percent mass from experimental data. | Convert percent mass to the simplest formula (empirical
formula).
TOP: Derivation of Formulas from Elemental Composition
10. ANS: E
PTS: 1
DIF: Moderate
OBJ: Determine the empirical formula from the percentage composition.
TOP: Percent Composition and Formulas of Compounds
NOT: Dynamic Question
11. ANS: E
PTS: 1
OBJ: Identify the sample with the greatest number of atoms.
TOP: Formula Weights, Molecular Weights, and Moles
NOT: OWL
12. ANS: A
PTS: 1
OBJ: Determine the number of atoms of one atom type in a compound.
TOP: Formula Weights, Molecular Weights, and Moles
NOT: OWL
13. ANS: A
PTS: 1
OBJ: Determine the number of molecules in a sample.
TOP: Formula Weights, Molecular Weights, and Moles
NOT: OWL
14. ANS: C
PTS: 1
OBJ: Determine the empirical and molecular formula given the ball and stick model.
TOP: Chemical Formulas
NOT: OWL
15. ANS: C
PTS: 1
8 CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
OBJ: Understand the implications of the Law of Conservation of Matter.
TOP: Chemical Equations
ANS: D
PTS: 1
OBJ: Understand the implications of the Law of Conservation of Matter.
TOP: Chemical Equations
ANS: D
PTS: 1
OBJ: Balance a chemical equation.
TOP: Chemical Equations
ANS: E
PTS: 1
OBJ: Balance a chemical equation.
TOP: Chemical Equations
ANS: E
PTS: 1
OBJ: Balance a chemical equation. | Sum the coefficients.
TOP: Chemical Equations
ANS: A
PTS: 1
OBJ: Balance a chemical equation. | Sum the coefficients.
TOP: Chemical Equations
ANS: D
PTS: 1
OBJ: Balance a chemical equation. | Sum the coefficients.
TOP: Chemical Equations
ANS: C
PTS: 1
OBJ: Balance a chemical equation. | Sum the coefficients.
TOP: Chemical Equations
ANS: C
PTS: 1
OBJ: Translate a balanced chemical equation into words.
TOP: Calculations Based on Chemical Equations
ANS: D
PTS: 1
OBJ: Use the balanced chemical reaction to convert molecules organic reactant to molecules dioxygen.
TOP: Calculations Based on Chemical Equations
ANS: A
PTS: 1
OBJ: Use the balanced chemical reaction to convert moles organic reactant to moles dioxygen.
TOP: Calculations Based on Chemical Equations
ANS: C
PTS: 1
OBJ: Use Avogadro's number, molecular weights, and the balanced chemical reaction to convert molecules
organic reactant to grams dioxygen.
TOP: Calculations Based on Chemical Equations
ANS: B
PTS: 1
OBJ: Use molecular weights and the balanced chemical reaction to convert grams organic reactant to grams
product.
TOP: Calculations Based on Chemical Equations
ANS: A
PTS: 1
OBJ: Use molecular weights, formula weights, and the balanced chemical reaction to convert grams reactant
to grams product.
TOP: Calculations Based on Chemical Equations
ANS: B
PTS: 1
OBJ: Use formula weights and the balanced chemical reaction to convert grams reactant to grams product.
TOP: Calculations Based on Chemical Equations
ANS: E
PTS: 1
DIF: Harder Question
OBJ: Use molecular weights and the balanced chemical equation to determine the limiting reactant. | Use the
limiting reactant, molecular weights, and the balanced chemical reaction to determine the theoretical yield. |
Calculate the percent yield given the actual yield.
TOP: Percent Yields from Chemical Reactions
ANS: E
PTS: 1
OBJ: Calculate volume of solution given grams solute and solution molarity.
TOP: Concentrations of Solutions
ANS: B
PTS: 1
DIF: Moderate
OBJ: Identify the limiting reactant.
TOP: The Limiting Reactant Concept
NOT: Dynamic Question
9
CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)
33. ANS: B
PTS: 1
OBJ: Know the definition of atomic number. | Understand the relationship of atomic number to the number of
electrons in a neutral atom. TOP:
Atomic Number
34. ANS: C
PTS: 1
OBJ: Use atomic mass and atomic weight to calculate isotopic abundance.
TOP: The Atomic Weight Scale and Atomic Weights
35. ANS: D
PTS: 1
OBJ: Identify the isotope with the greatest percent abundance based on atomic weight.
TOP: The Atomic Weight Scale and Atomic Weights
NOT: OWL
36. ANS: E
PTS: 1
OBJ: Write a balanced chemical equation for the combustion of a hydrocarbon in excess oxygen. | Sum the
coefficients.
TOP: Oxygen and the Oxides
10
CHEM 1411. Chapter3. Mass Relations in Chemical Reactions (Homework)