Deck 3: Stoichiometry: Ratios of Combination

Question 1

Calculate the molecular mass of menthol, C₁₀H₂₀O.

A) 156 amu
B) 140 amu
C) 29 amu
D) 146 amu
E) 136 amu

Answer 1

156 amu

Question 2

How many moles of aspirin, C₉H₈O₄, are in a tablet that contains 325 mg of aspirin?

A) 0.00180 moles
B) 0.555 moles
C) 0.467 moles
D) 0.357 moles
E) 2.80 moles

Answer 2

0.00180 moles

Question 3

Household sugar, sucrose, has the molecular formula C₁₂H₂₂O₁₁. What is the % of carbon in sucrose, by mass?

A) 26.7%
B) 33.3%
C) 41.4%
D) 42.1%
E) 51.4%

Answer 3

42.1%

Question 4

Calculate the molecular mass of tetraphosphorus decaoxide, P₄O₁₀, a corrosive substance which can be used as a drying agent.

A) 469.73 amu
B) 283.88 amu
C) 190.97 amu
D) 139.88 amu
E) 94.97 amu

Question 5

How many grams are present in 0.885 moles of manganese?

A) 62.1 g
B) 48.6 g
C) 21.5 g
D) 27.5 g
E) 0.016 g

Question 6

What is the percent sodium in sodium carbonate?

A) 43.4%
B) 11.3%
C) 45.3%
D) 27.7%
E) 21.7%

Question 7

What is the mass percent of oxygen in barium perchlorate?

A) 4.7%
B) 8.5%
C) 23.4%
D) 38.1%
E) 19.0%

Question 8

What is the molar mass of nicotine, C₁₀H₁₄N₂?

A) 134 g/mol
B) 148 g/mol
C) 158 g/mol
D) 210 g/mol
E) 162 g/mol

Question 9

What is the percent carbon in CH₃CH₂OH?

A) 13%
B) 26%
C) 35%
D) 46%
E) 52%

Question 10

How many moles of ammonia, NH₃, are in 13.81 g of NH₃?

A) 1.234 moles
B) 0.8107 moles
C) 8.316 × 10²⁴ moles
D) 4.881 × 10²³ moles
E) 235.3 moles

Question 11

What is the molecular mass of acetaminophen, C₈H₉NO₂?

A) 43 amu
B) 76 amu
C) 151 amu
D) 162 amu
E) 125 amu

Question 12

How many grams are contained in a 0.893 mol sample of methane, CH₄?

A) 1.48 × 10^-24 g
B) 5.38 × 10²³ g
C) 8.64 × 10²⁴ g
D) 14.3 g
E) 18.0 g

Question 13

Calculate the formula mass of ammonium arsenate, (NH₄)₃AsO₄.

A) 417.80 amu
B) 193.05 amu
C) 165.02 amu
D) 156.96 amu
E) 108.96 amu

Question 14

Calculate the formula mass of potassium permanganate, KMnO₄.

A) 149.91 amu
B) 79.41 amu
C) 127.41 amu
D) 158.04 amu
E) 174.04 amu

Question 15

What is the percent sulfur in iron(III) sulfate?

A) 28%
B) 32%
C) 24%
D) 48%
E) 42%

Question 16

Calculate the molar mass of Ca(BO₂)₂·6H₂O.

A) 273.87 g/mol
B) 233.80 g/mol
C) 183.79 g/mol
D) 174.89 g/mol
E) 143.71 g/mol

Question 17

Aluminum sulfate, Al₂(SO₄)₃, is used in tanning leather, purifying water, and the manufacture of antiperspirants. Calculate its formula mass.

A) 450.06 amu
B) 342.17 amu
C) 315.15 amu
D) 278.02 amu
E) 74.98 amu

Question 18

How many moles are present in 17.4 g of lead?

A) 0.0994 moles
B) 1.05 × 10²⁵ moles
C) 0.0840 moles
D) 10.06 moles
E) 11.9 moles

Question 19

Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH)₂.

A) 3.28 mol
B) 2.32 mol
C) 0.431 mol
D) 0.305 mol
E) 0.200 mol

Question 20

Calculate the formula mass of rubidium carbonate, Rb₂CO₃.

A) 340.43 amu
B) 255.00 amu
C) 230.95 amu
D) 145.47 amu
E) 113.48 amu

Question 21

Smooth muscle myosin is a motor protein that plays a crucial role in the contraction of smooth muscle. If this protein has a molar mass of 480,000 grams/mol, what is the mass, in grams, of 27 moles of smooth muscle myosin?

A) 1.8 × 10⁴ g
B) 1.3 × 10⁷ g
C) 1.8 × 10² g
D) 2.8 × 10²⁹ g
E) None of the answers is correct.

Question 22

As a research assistant, you are asked to prepare a 3.00 liter solution of magnesium sulfate at 45.0 micromoles per liter. How many moles of magnesium sulfate are required to make this solution?

A) 0.000135 moles
B) 0.0000150 moles
C) 1.35 × 10⁸ moles
D) 1.50 × 10⁷ moles
E) None of the answers is correct.

Question 23

Calculate the mass in grams of 8.35 × 10²² molecules of CBr₄.

A) 0.0217 g
B) 0.139 g
C) 7.21 g
D) 12.7 g
E) 46.0 g

Question 24

What is the mass of 1.63 × 10²¹ atoms of silicon? (N_A = 6.022 × 10²³ mol^-1)

A) 2.71 × 10^-23 g
B) 4.58 × 10²² g
C) 28.08 g
D) 1.04 × 10⁴ g
E) 7.60 × 10^-2 g

Question 25

Determine the number of ammonia molecules in 4.85 g of ammonia. (N_A = 6.022 × 10²³ mol^-1)

A) 2.92 × 10²³ molecules
B) 4.73 × 10^-25 molecules
C) 1.24 × 10²³ molecules
D) 5.83 × 10^-24 molecules
E) 1.71 × 10²³ molecules

Question 26

Aluminum oxide, Al₂O₃, is used as a filler for paints and varnishes as well as in the manufacture of electrical insulators. Calculate the number of moles in 47.51 g of Al₂O₃.

A) 2.377 mol
B) 2.146 mol
C) 1.105 mol
D) 0.4660 mol
E) 0.4207 mol

Question 27

The density of water is 1.00 g/mL at 4°C. How many water molecules are present in 6.25 mL of water at this temperature? (N_A = 6.022 × 10²³ mol^-1)

A) 6.27 × 10²³ molecules
B) 3.76 × 10²⁴ molecules
C) 2.09 × 10²³ molecules
D) 6.02 × 10²³ molecules
E) 0.347 molecules

Question 28

What is the mass of 7.80 × 10¹⁸ carbon atoms? (N_A = 6.022 × 10²³ mol^-1)

A) 1.30 × 10^-5 g
B) 6.43 × 10³ g
C) 7.80 × 10¹⁸ g
D) 1.56 × 10^-4 g
E) 12.01 g

Question 29

Sulfur trioxide can react with atmospheric water vapor to form sulfuric acid that falls as acid rain. Calculate the mass in grams of 3.65 × 10²⁰ molecules of sulfur trioxide.

A) 6.06 × 10^-4 g
B) 2.91 × 10^-2 g
C) 4.85 × 10^-2 g
D) 20.6 g
E) 1650 g

Question 30

What is the mass of 0.0250 mol of P₂O₅?

A) 35.5 g
B) 5676 g
C) 0.0250 g
D) 1.51 × 10²² g
E) 3.55 g

Question 31

What is the mass of 1.21 × 10²⁰ atoms of sulfur? (N_A = 6.022 × 10²³ mol^-1)

A) 3.88 × 10²¹ g
B) 2.00 mg
C) 32.06 g
D) 6.44 mg
E) 2.00 × 10^-4 g

Question 32

How many grams are contained in a 0.183 mol sample of ammonium phosphate?

A) 1.23 × 10^-3 g
B) 617 g
C) 20.7 g
D) 27.3 g
E) 815.1 g

Question 33

What is the average mass, in grams, of one atom of iron? (N_A = 6.022 × 10²³ mol^-1)

A) 6.02 × 10²³ g
B) 1.66 × 10^-24 g
C) 9.27 × 10^-23 g
D) 55.85 g
E) 55.85 × 10^-23 g

Question 34

Proteins found in humans are polymers that consist of different combinations of 20 amino acids. Proline, one of the 20 amino acids, has the molecular formula, C₅H₉NO₂. If a human protein has 25 proline monomers, how many carbon atoms from proline are present in the protein?

A) 4 C atoms
B) 25 C atoms
C) 40 C atoms
D) 100 C atoms
E) 125 C atoms

Question 35

What is the mass in grams of 0.250 mol of the common antacid calcium carbonate?

A) 4.00 × 10² g
B) 25.0 g
C) 17.0 g
D) 4.00 × 10^-2 g
E) 2.50 × 10^-3 g

Question 36

Which of the following substances contains the greatest mass of carbon?

A) 100 g CH₄
B) 100 g C₂H₄
C) 100 g CCl₄
D) 100 g CH₂Cl₂
E) 100 g CO₂

Question 37

What is the average mass of one copper atom? (NA = 6.022 × 1023 mol^-1)

A) 1.055 × 10^-22 g
B) 63.55 g
C) 1 amu
D) 1.66 × 10^-24 g
E) 9.476 × 10²¹ g

Question 38

Phosphorus pentachloride, a white solid that has a pungent, unpleasant odor, is used as a catalyst for certain organic reactions. Calculate the number of moles in 38.7 g of phosphorus pentachloride.

A) 5.38 mol
B) 3.55 mol
C) 0.583 mol
D) 0.282 mol
E) 0.186 mol

Question 39

What is the average mass, in grams, of one arsenic atom? (N_A = 6.022 × 10²³ mol^-1)

A) 5.48 × 10^-23 g
B) 33.0 g
C) 74.9 g
D) 1.24 × 10^-22 g
E) 8.04 × 10²¹ g

Question 40

Calculate the mass of 3.00 moles of CF₂Cl₂.

A) 3.00 g
B) 174 g
C) 363 g
D) 1.81 × 10²⁴ g
E) 40.3

Question 41

What is the empirical formula for a 100-g sample containing 87.42 g of nitrogen and 12.58 g of hydrogen?

A) NH
B) N₂H
C) NH₂
D) NH₃
E) N₇H

Question 42

Once the following equation is balanced with the smallest set of whole number coefficients, what is the sum of the coefficients? (Don't forget to include coefficients of one.) ________ Al + ________ H₂SO₄ → ________ Al₂(SO₄)₃ + ________ H₂

A) 3
B) 5
C) 6
D) 9
E) 12

Question 43

Calculate the molar mass of sulfuric acid.

A) 98.086 g/mol
B) 81.078 g/mol
C) 49 g/mol
D) 41 g/mol
E) None of the answers are correct.

Question 44

When a chemical equation is balanced, it will have a set of whole number coefficients that cannot be reduced to smaller whole numbers. What is the coefficient for O₂ when the following combustion reaction of a hydrocarbon is balanced? ________ C₇H₁₄ + ________ O₂ → ________ CO₂ + ________ H₂O

A) 42
B) 21
C) 11
D) 10
E) None of these answers is correct.

Question 45

Balance the following equation: Ca₃(PO₄)₂(s) + SiO₂(s) + C(s) → CaSiO₃(s) + CO(g) + P₄(s)

A) Ca₃(PO₄)₂(s) + 3SiO₂(s) + 8C(s) → 3CaSiO₃(s) + 8CO(g) + P₄(s)
B) Ca₃(PO₄)₂(s) + 3SiO₂(s) + 14C(s) → 3CaSiO₃(s) + 14CO(g) + P₄(s)
C) Ca₃(PO₄)₂(s) + 3SiO₂(s) + 8C(s) → 3CaSiO₃(s) + 8CO(g) + 2P₄(s)
D) 2Ca₃(PO₄)₂(s) + 6SiO₂(s) + 10C(s) → 6CaSiO₃(s) + 10CO(g) + P₄(s)
E) 2Ca₃(PO₄)₂(s) + 6SiO₂(s) + 10C(s) → 6CaSiO₃(s) + 10CO(g) + 4P₄(s)

Question 46

Balance the following equation: C₈H₁₈O₃(l) + O₂(g) → H₂O(g) + CO₂(g)

A) C₈H₁₈O₃(l) + 8O₂(g) → 9H₂O(g) + 8CO₂(g)
B) C₈H₁₈O₃(l) + 11O₂(g) → 9H₂O(g) + 8CO₂(g)
C) 2C₈H₁₈O₃(l) + 22O₂(g) → 9H₂O(g) + 16CO₂(g)
D) C₈H₁₈O₃(l) + 13O₂(g) → 18H₂O(g) + 8CO₂(g)
E) 2C₈H₁₈O₃(l) + 17O₂(g) → 18H₂O(g) + 16CO₂(g)

Question 47

Balance the following equation: UO₂(s) + HF(l) → UF₄(s) + H₂O(l)

A) UO₂(s) + 2HF(l) → UF₄(s) + H₂O(l)
B) UO₂(s) + 4HF(l) → UF₄(s) + 2H₂O(l)
C) UO₂(s) + H₄F₄(l) → UF₄(s) + H₄O₂(l)
D) UO₂(s) + 4HF(l) → UF₄(s) + 4H₂O(l)
E) UO₂(s) + 8HF(l) → 2UF₄(s) + 4H₂O(l)

Question 48

Balance the following equation for the combustion of benzene: C₆H₆(l) + O₂(g) → H₂O(g) + CO₂(g)

A) C₆H₆(l) + 9O₂(g) → 3H₂O(g) + 6CO₂(g)
B) C₆H₆(l) + 9O₂(g) → 6H₂O(g) + 6CO₂(g)
C) 2C₆H₆(l) + 15O₂(g) → 6H₂O(g) + 12CO₂(g)
D) C₆H₆(l) + 15O₂(g) → 3H₂O(g) + 6CO₂(g)
E) 2C₆H₆(l) + 9O₂(g) → 6H₂O(g) + 12CO₂(g)

Question 49

Balance the following equation: B₂O₃(s) + HF(l) → BF₃(g) + H₂O(l)

A) B₂O₃(s) + 6HF(l) → 2BF₃(g) + 3H₂O(l)
B) B₂O₃(s) + H₆F₆ (l) → B₂F₆(g) + H₆O₃(l)
C) B₂O₃(s) + 2HF(l) → 2BF₃(g) + H₂O(l)
D) B₂O₃(s) + 3HF(l) → 2BF₃(g) + 3H₂O(l)
E) B₂O₃(s) + 6HF(l) → 2BF₃(g) + 6H₂O(l)

Question 50

Once the following equation is balanced with the smallest set of whole number coefficients, what is the sum of the coefficients? (Don't forget to include coefficients of one.) ________ Cr + ________ H₂SO₄ → ________ Cr₂(SO₄)₃ + _{________} H₂

A) 4
B) 9
C) 11
D) 13
E) 15

Question 51

What is the coefficient of H₂O when the following equation is properly balanced with the smallest set of whole numbers? ________ Na + ________ H₂O → ________ NaOH + ________ H₂

A) 1
B) 2
C) 3
D) 4
E) 5

Question 52

What is the coefficient of H₂SO₄ when the following equation is properly balanced with the smallest set of whole numbers? ________ Ca₃(PO₄)₂ + ________ H₂SO₄ → ________ CaSO₄ + ________ H₃PO₄

A) 3
B) 8
C) 10
D) 11
E) None of these answers is correct.

Question 53

What is the coefficient of O₂ when the following equation is properly balanced with the smallest set of whole numbers? ________ CH₃OH + ________ O₂ → ________ CO₂ + ________ H₂O

A) 1
B) 2
C) 3
D) 7
E) None of these answers is correct.

Question 54

What is the coefficient of O₂ when the following equation is properly balanced with the smallest set of whole numbers? ________ C₂H₄ + ________ O₂ → ________ CO₂ + ________ H₂O

A) 1
B) 2
C) 3
D) 4
E) 6

Question 55

What is the coefficient of H₂O when the following equation is properly balanced with the smallest set of whole numbers? ________ Al₄C₃ + ________ H₂O → ________ Al(OH)₃ + ________ CH₄

A) 3
B) 4
C) 6
D) 12
E) 24

Question 56

What is the coefficient of H₂O when the following equation is properly balanced with the smallest set of whole numbers? ________ PCl₃(l) + ________ H₂O(l) → ________ H₃PO₃(aq) + ________ HCl(aq)

A) 1
B) 2
C) 3
D) 5
E) None of these answers is correct.

Question 57

What is the coefficient preceding O₂ when the following combustion reaction of a fatty acid is properly balanced using the smallest set of whole numbers? ________ C₁₈H₃₆O₂ + ________ O₂ → ________ CO₂ + ________ H₂O

A) 1
B) 8
C) 9
D) 26
E) 27

Question 58

Once the following equation is balanced with the smallest set of whole number coefficients, what is the sum of the coefficients? (Don't forget to include coefficients of one.) ________ SF₄ + ________ H₂O → ________ H₂SO₃ + ________ HF

A) 4
B) 6
C) 7
D) 9
E) None of these answers is correct.

Question 59

Once the following equation is balanced with the smallest set of whole number coefficients, what is the sum of the coefficients? (Don't forget to include coefficients of one.) ________ CH₄ + ________ Cl₂ → _{________} CCl₄ + ________ HCl

A) 4
B) 6
C) 8
D) 10
E) 12

Question 60

What is the name given to the quantitative relationship between the substances that are consumed and produced in a chemical reaction?

A) Law of definite proportions
B) Law of molecular balance
C) Percent composition
D) Stoichiometry
E) Percent equivalency

Question 61

Hydroxylammonium nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass % O. What is its empirical formula?

A) HNO
B) H₂NO₂
C) HN₆O₁₆
D) HN₁₆O₇
E) H₂NO₃

Question 62

How many grams of calcium metal is required to react with 7.75 g water to produce calcium hydroxide and hydrogen gas?

A) 8.62 g
B) 34.5 g
C) 4.31 g
D) 40.1 g
E) 17.2 g

Question 63

Aluminum reacts with bromine to form aluminum bromide (used as an acid catalyst in organic synthesis). Al(s) + Br₂(l) → Al₂Br₆(s) [unbalanced]
How many moles of Al are needed to form 2.43 mol of Al₂Br₆?

A) 7.29 mol
B) 4.86 mol
C) 2.43 mol
D) 1.62 mol
E) 1.22 mol

Question 64

Terephthalic acid, used in the production of polyester fibers and films, is composed of carbon, hydrogen, and oxygen. When 0.6943 g of terephthalic acid was subjected to combustion analysis, it produced 1.471 g CO₂ and 0.226 g H₂O. What is its empirical formula?

A) C₂H₃O₄
B) C₃H₄O₂
C) C₄H₃O₂
D) C₅H₁₂O₄
E) C₂H₂O

Question 65

The percent composition by mass of a compound is 76.0% C, 12.8% H, and 11.2% O. The molar mass of this compound is 284.5 g/mol. What is the molecular formula of the compound?

A) C₁₀H₆O
B) C₉H₁₈O
C) C₁₆H₂₈O₄
D) C₂₀H₁₂O₂
E) C₁₈H₃₆O₂

Question 66

What is the empirical formula for a sample containing 81.70% carbon and 18.29% hydrogen?

A) CH
B) CH₃
C) C₂H₆
D) CH₄
E) C₃H₈

Question 67

What mass of oxygen is required to react with calcium to produce 44.8 g calcium oxide?

A) 12.8 g
B) 25.6 g
C) 6.39 g
D) 0.399 g
E) 51.1 g

Question 68

What mass of sodium carbonate is required for complete reaction with 8.35 g of nitric acid to produce sodium nitrate, carbon dioxide, and water?

A) 28.1 g
B) 14.04 g
C) 4.96 g
D) 7.02 g
E) 400.0 g

Question 69

A compound containing chromium and silicon contains 73.52 mass percent chromium. Determine its empirical formula.

A) CrSi₃
B) Cr₂Si₃
C) Cr₃Si
D) Cr₃Si₂
E) Cr₄Si₃

Question 70

Ammonia reacts with fluorine to produce dinitrogen tetrafluoride and hydrogen fluoride (used in the production of aluminum, in uranium processing, and in the frosting of light bulbs). 2NH₃(g) + 5F₂(g) → N₂F₄(g) + 6HF(g)
How many moles of NH₃ are needed to react completely with 13.6 mol of F₂?

A) 34.0 mol
B) 27.2 mol
C) 6.80 mol
D) 5.44 mol
E) 2.27 mol

Question 71

A compound was discovered whose composition by mass is 85.6% C and 14.4% H. Which of these formulas could be the molecular formula of this compound?

A) CH₄
B) C₂H₄
C) C₃H₄
D) C₂H₆
E) C₃H₈

Question 72

What mass of nitrogen gas is required to react completely with 2.79 g of hydrogen gas to produce ammonia?

A) 25.8 g
B) 12.9 g
C) 78.2 g
D) 38.7 g
E) 77.4 g

Question 73

What is the empirical formula of a compound of uranium and fluorine that is composed of 67.6% uranium and 32.4% fluorine by mass?

A) U₂F
B) U₃F₄
C) UF₄
D) UF₆
E) UF₈

Question 74

Hydroxyl ammonium nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass % O. If its molar mass is between 94 and 98 g/mol, what is its molecular formula?

A) NH₂O₅
B) N₂H₄O₄
C) N₃H₃O₃
D) N₄H₈O₂
E) N₂H₂O₄

Question 75

How many grams of lead(II) chloride is produced if 13.87 g lead(II) nitrate combines with excess hydrochloric acid to produce lead(II) chloride and nitric acid?

A) 5.82 g
B) 14.33 g
C) 0.086 g
D) 11.64 g
E) 16.52 g

Question 76

Sulfur dioxide reacts with chlorine to produce thionyl chloride (used as a drying agent for inorganic halides) and dichlorine oxide (used as a bleach for wood, pulp and textiles). SO₂(g) + 2Cl₂(g) → SOCl₂(g) + Cl₂O(g)
If 0.400 mol of Cl₂ reacts with excess SO₂, how many moles of Cl₂O are formed?

A) 0.800 mol
B) 0.400 mol
C) 0.200 mol
D) 0.100 mol
E) 0.0500 mol

Question 77

A certain compound of bromine and fluorine is used to make UF₆, which is an important chemical in the processing and reprocessing of nuclear fuel. The compound contains 58.37 mass percent bromine. What is its empirical formula?

A) BrF
B) BrF₂
C) Br₂F₃
D) Br₃F
E) BrF₃

Question 78

An oxide of gadolinium contains 86.76 mass % Gd. What is its empirical formula?

A) Gd₂O₃
B) Gd₃O₂
C) Gd₃O₄
D) Gd₁₃O₂
E) GdO

Question 79

What mass of nitrogen gas is required to react completely with excess hydrogen gas to produce 13.6 g of ammonia?

A) 11.2 g
B) 0.06 g
C) 22.4 g
D) 16.5 g
E) 44.8 g

Question 80

What mass of ammonia is formed when 5.36 g of nitrogen gas reacts with excess hydrogen gas?

A) 3.26 g
B) 0.629 g
C) 13.04 g
D) 17.63 g
E) 6.52 g