Deck 3: Stoichiometry: Calculations With Chemical Formulas and Equations

Question 1

The mass % of H in methane (CH₄) is .

A) 74.87
B) 4.032
C) 25.13
D) 92.26
E) 7.743

Answer 1

25.13

Question 2

The formula weight of ammonium sulfate ((NH₄)₂SO₄) is _ amu.

A) 264
B) 100
C) 132
D) 116
E) 118

Answer 2

132

Question 3

Automotive air bags inflate when sodium azide decomposes explosively to its constituent elements:
How many grams of sodium azide are required to produce 18.0 g of nitrogen?

A) 62.7
B) 0.964
C) 0.428
D) 41.8
E) 27.9

Answer 3

27.9

Question 4

Lithium and nitrogen react in a combination reaction to produce lithium nitride:

How many moles of N₂ are needed to react with 0.500 mol of lithium?

A) 1.50
B) 0.0833
C) 3.00
D) 0.167
E) 0.500

Question 5

The mass % of Al in aluminum sulfate (Al₂(SO₄)₃) is .

A) 45.70
B) 21.93
C) 35.94
D) 7.886
E) 15.77

Question 6

The formula weight of aluminum sulfate (Al₂(SO₄)₃) is _ amu.

A) 123.04
B) 342.14
C) 273.06
D) 59.04
E) 150.14

Question 7

How many oxygen atoms are contained in 2.74 g of Al₂(SO₄)₃?

A) 12
B) 6.02 × 10²³
C) 5.79 × 10²²
D) 8.01 × 10^{- 3}
E) 7.22 × 10²⁴

Question 8

The formula weight of magnesium fluoride (MgF₂) is _ amu.

A) 92.9
B) 62.3
C) 86.6
D) 67.6
E) 43.3

Question 9

How many oxygen atoms are there in 52.06 g of carbon dioxide?

A) 1.018 × 10²⁴
B) 1.424 × 10²⁴
C) 6.022 × 10²³
D) 5.088 × 10²³
E) 1.204 × 10²⁴

Question 10

How many sulfur dioxide molecules are there in 0.180 mol of sulfur dioxide?

A) 1.08 × 10²⁴
B) 6.02 × 10²⁴
C) 6.02 × 10²³
D) 1.80 × 10²³
E) 1.08 × 10²³

Question 11

Magnesium burns in air with a dazzling brilliance to produce magnesium oxide:
2Mg (s) + O₂ (g) - 2MgO (s)
How many moles of O₂ are consumed when 0.770 mol of magnesium burns?

A) 1.54
B) 0.385
C) 2.60
D) 0.770
E) 0.0317

Question 12

Automotive air bags inflate when sodium azide decomposes explosively to its constituent elements:

How many moles of N₂ are produced by the decomposition of 2.88 mol of sodium azide?

A) 4.32
B) 1.92
C) 0.960
D) 1.44
E) 8.64

Question 13

Calculate the percentage by mass of nitrogen in PtCl₂(NH₃)₂.

A) 4.67
B) 9.34
C) 4.95
D) 12.67
E) 9.90

Question 14

Lithium and nitrogen react in a combination reaction to produce lithium nitride:

How many moles of lithium are needed to produce 0.60 mol of Li₃N when the reaction is carried out in the presence of excess nitrogen?

A) 0.20
B) 3.6
C) 1.8
D) 0.40
E) 0.30

Question 15

When a hydrocarbon burns in air, what component of air reacts?

A) nitrogen
B) water
C) oxygen
D) carbon dioxide
E) argon

Question 16

What is the mass % of carbon in dimethylsulfoxide (C₂H₆SO)?

A) 79.8
B) 60.0
C) 20.6
D) 7.74
E) 30.7

Question 17

What is the empirical formula of a compound that is 64.8% C, 13.6% H, and 21.6% O by mass?

A) C₅HO₂
B) C₄HO₁
C) C₈H₂₀O₂
D) C₅H₁₄O₁
E) C₄H₁₀O₁

Question 18

How many grams of sodium carbonate contain 1.773 × 10¹⁷ carbon atoms?

A) 3.121 × 10^{- 5}
B) 1.011 × 10^{- 5}
C) 6.066 × 10^{- 5}
D) 1.517 × 10^{- 5}
E) 9.100 × 10^{- 5}

Question 19

Which hydrocarbon pair below have identical mass percentage of C?

A) C₂H₄ and C₄H₂
B) C₂H₄ and C₃H₄
C) C₃H₄ and C₃H₆
D) C₂H₄ and C₃H₆
E) none of the above

Question 20

The mass % of C in methane (CH₄) is .

A) 7.743
B) 74.87
C) 92.26
D) 25.13
E) 133.6

Question 21

One mole of contains the largest number of atoms.

A) C₁₀H₈
B) Na₃PO₄
C) Cl₂
D) S₈
E) Al₂(SO₄)₃

Question 22

What is the mass in grams of 9.76 × 10¹² atoms of naturally occurring sodium?

A) 1.62 × 10^{- 11}
B) 7.05 × 10^{- 13}
C) 2.24 × 10¹⁴
D) 22.99
E) 3.73 × 10^{- 10}

Question 23

Calculate the percentage by mass of chlorine in PtCl₂(NH₃)₂.

A) 23.63
B) 12.53
C) 25.05
D) 11.82
E) 18.09

Question 24

The molecular weight of the acetic acid (CH₃CO₂H) is amu.

A) 60
B) 48
C) 32
D) 44

Question 25

The formula of nitrobenzene is C₆H₅NO₂. The molecular weight of this compound is amu.

A) 109.10
B) 43.03
C) 123.11
D) 107.11
E) 3.06

Question 26

There are _ atoms of oxygen are in 300 molecules of CH₃CO₂H.

A) 600
B) 3.01 × 10²⁴
C) 1.80 × 10²⁶
D) 300
E) 3.61 × 10²⁶

Question 27

A sample of CH₂F₂ with a mass of 19 g contains _ atoms of F.

A) 38
B) 9.5
C) 2.2 × 10²³
D) 4.4 × 10²³
E) 3.3 × 10²⁴

Question 28

Calculate the percentage by mass of hydrogen in PtCl₂(NH₃)₂.

A) 1.008
B) 0.034
C) 2.016
D) 0.672
E) 1.558

Question 29

The molecular weight of the ethanol (C₂H₅OH) is amu.

A) 30
B) 92
C) 34
D) 41
E) 46

Question 30

Lithium and nitrogen react in a combination reaction to produce lithium nitride:
6Li (s) + N₂ (g) -2Li₃N (s)
How many moles of lithium nitride are produced when 0.450 mol of lithium react in this fashion?

A) 1.35
B) 0.0750
C) 0.150
D) 0.225
E) 0.900

Question 31

The formula weight of a substance is .

A) the weight of a sample of the substance
B) identical to the molar mass
C) the same as the percent by mass weight
D) the sum of the atomic weights of each atom in its chemical formula
E) determined by combustion analysis

Question 32

How many atoms of nitrogen are in 10 g of NH₄NO₃?

A) 2
B) 3.0 × 10²³
C) 1.8
D) 3.5
E) 1.5 × 10²³

Question 33

Gaseous argon has a density of 1.40 g/L at standard conditions. How many argon atoms are in 1.00 L of argon gas at standard conditions?

A) 4.7 × 10²²
B) 2.1 × 10²²
C) 3.4 × 10²⁵
D) 1.5 × 10²⁵
E) 6.02 × 10²³

Question 34

A nitrogen oxide is 63.65% by mass nitrogen. The molecular formula could be _ _.

A) N₂O₄
B) N₂O
C) NO₂
D) NO
E) either NO₂ or N₂O₄

Question 35

A sulfur oxide is 50.0% by mass sulfur. This molecular formula could be .

A) S₂O₄
B) SO₂
C) S₂O
D) SO
E) either SO₂ or S₂O₄

Question 36

The formula weight of potassium phosphate (K₃PO₄) is _ amu.

A) 212.27
B) 86.07
C) 251.37
D) 173.17
E) 196.27

Question 37

How many sulfur dioxide molecules are there in 1.80 mol of sulfur dioxide?

A) 1.80 × 10²⁴
B) 6.02 × 10²⁴
C) 6.02 × 10²³
D) 1.08 × 10²³
E) 1.08 × 10²⁴

Question 38

Of the reactions below, which one is a decomposition reaction?

A) 2CH₄ + 4O₂ -2CO₂ + 4H₂O
B) 2Mg + O₂ - 2MgO
C) Cd(NO₃)₂ + Na₂S - CdS + 2NaNO₃
D) 2N₂ + 3H₂ - 2NH₃
E) NH₄Cl - NH₃ + HCl

Question 39

A sample of CH₄O with a mass of 32.0 g contains molecules of CH₄O.

A) 32.0
B) 1.00
C) 5.32 × 10^{- 23}
D) 1.88 × 10²²
E) 6.02 × 10²³

Question 40

One million argon atoms is mol of argon atoms.

A) 3
B) 1.0 × 10^{- 6}
C) 1.7 × 10^{- 18}
D) 1.0 × 10⁺⁶
E) 6.0 × 10²³

Question 41

How many molecules of CH₄ are in 48.2 g of this compound?

A) 5.00 × 10²⁴
B) 4.00
C) 3.00
D) 2.90 × 10²⁵
E) 1.81 × 10²⁴

Question 42

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide:

In a particular experiment, a 5.00- g sample of CaO is reacted with excess water and 6.11 g of Ca(OH)₂ is recovered. What is the percent yield in this experiment?

A) 7.19
B) 122
C) 81.9
D) 1.22
E) 92.4

Question 43

Of the reactions below, which one is not a combination reaction?

A) 2CH₄ + 4O₂ -2CO₂ + 4H₂O
B) CaO + H₂O - Ca(OH)₂
C) 2Mg + O₂ - 2MgO
D) C + O₂ - CO₂
E) 2N₂ + 3H₂ - 2NH₃

Question 44

The formula weight of silver chromate (Ag₂CrO₄) is _ amu.

A) 159.87
B) 175.87
C) 223.87
D) 331.73
E) 339.86

Question 45

Water can be formed from the stoichiometric reaction of hydrogen with oxygen:

A complete reaction of 5.0 g of O₂ with excess hydrogen produces g of H₂O.

Question 46

How many moles of pyridine (C₅H₅N) are contained in 3.13 g of pyridine?

A) 0.00404
B) 0.0396
C) 25.3
D) 4.04 × 10³
E) 0.319

Question 47

The reaction used to inflate automobile airbags _.

A) is a decomposition reaction
B) produces sodium gas
C) violates the law of conservation of mass
D) is a combination reaction
E) is a combustion reaction

Question 48

Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide:

A 1)50- g sample of CaO is reacted with 1.45 g of H₂O. How many grams of water remains after completion of reaction?

A) 0.00
B) 0.0536
C) 0.966
D) 1.04
E) 0.00297

Question 49

Which one of the following is not true concerning automotive air bags?

A) The gas used for inflating them is oxygen
B) A gas is produced when the air bag activates.
C) They are loaded with sodium azide initially
D) The two products of the decomposition reaction are sodium and nitrogen
E) They are inflated as a result of a decomposition reaction

Question 50

The formula weight of calcium nitrate (Ca(NO₃)₂) is _ amu.

A) 150.1
B) 204.2
C) 102.1
D) 116.1
E) 164.0

Question 51

The formula weight of potassium dichromate (K₂Cr₂O₇) is _ amu.

A) 242.18
B) 107.09
C) 333.08
D) 255.08
E) 294.18

Question 52

The total number of atoms in 0.111 mol of Fe(CO)₃(PH₃)₂ is _ .

A) 15
B) 1.67
C) 1.07 × 10²⁴
D) 2.76 × 10^{- 24}
E) 4.46 × 10²¹

Question 53

Which one of the following substances is the product of this combination reaction?
Al (s) + I₂ (s) -

A) AlI
B) AlI₃
C) Al₂I₃
D) Al₃I₂
E) AlI₂

Question 54

The mass % of F in the binary compound KrF₂ is _ .

A) 45.38
B) 68.80
C) 18.48
D) 81.52
E) 31.20

Question 55

The molecular weight of urea ( (NH₂)₂CO ), a compound used as a nitrogen fertilizer, is
Amu)

A) 43.0
B) 8.0
C) 44.0
D) 32.0
E) 60.1

Question 56

How many carbon atoms are there in 52.06 g of carbon dioxide?

A) 3.134 × 10²⁵
B) 1.424 × 10²⁴
C) 7.122 × 10²³
D) 5.206 × 10²⁴
E) 8.648 × 10^{- 23}

Question 57

The combustion of propane (C₃H₈ ) in the presence of excess oxygen yields CO₂ and H₂O:
C₃H₈ (g) + 5O₂ (g) - 3CO₂ (g) + 4H₂O (g)
When 7.3 g of C₃H₈ burns in the presence of excess O₂, _ g of CO₂ is produced.

Question 58

How many moles of sodium carbonate contain 1.773 × 10¹⁷ carbon atoms?

A) 2.945 × 10^{- 7}
B) 8.836 × 10^{- 7}
C) 5.890 × 10^{- 7}
D) 9.817 × 10^{- 8}
E) 1.473 × 10^{- 7}

Question 59

A compound was found to contain 90.6% lead (Pb) and 9.4% oxygen. The empirical formula for this compound is .

Question 60

If 294 grams of FeS₂ is allowed to react with 176 grams of O₂ according to the following equation, how many grams of Fe₂O₃ are produced?

Question 61

A certain alcohol contains only three elements, carbon, hydrogen, and oxygen. Combustion of a 50.00 gram sample of the alcohol produced 95.50 grams of CO₂ and 58.70 grams of H₂O. What is the empirical formula of the alcohol?

Question 62

What is the empirical formula of a compound that contains 27.0% S, 13.4% O, and 59.6% Cl by mass?

A) SOCl₂
B) S₂OCl
C) SOCl
D) SO₂Cl
E) ClSO₄

Question 63

When the following equation is balanced, the coefficient of H₂O is _ .

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

Question 64

When the following equation is balanced, the coefficient of H₃PO₄ is _ .

A) 2
B) 0
C) 1
D) 3
E) 4

Question 65

There are _ mol of carbon atoms in 4 mol of dimethylsulfoxide (C₂H₆SO).

A) 2
B) 8
C) 4
D) 6
E) 3

Question 66

When the following equation is balanced, the coefficient of Al is .

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

Question 67

The combustion of ammonia in the presence of excess oxygen yields NO₂ and H₂O:

The combustion of 28.8 g of ammonia consumes g of oxygen.

A) 108
B) 94.9
C) 28.8
D) 54.1
E) 15.3

Question 68

When the following equation is balanced, the coefficient of H₂SO₄ is _ .

A) 2
B) 3
C) 0.5
D) 1
E) 4

Question 69

Complete and balance the following reaction, given that elemental rubidium reacts with elemental sulfur to form Rb₂S (s).
Na (s) + S (s) -

Question 70

The combustion of carbon disulfide in the presence of excess oxygen yields carbon dioxide and sulfur dioxide:

The combustion of 15 g of CS₂ in the presence of excess oxygen yields g of SO₂.

Question 71

When the following equation is balanced, the coefficient of HCl is .

A) 2
B) 1
C) 0
D) 4
E) 3

Question 72

How many moles of magnesium oxide are produced by the reaction of 3.82 g of magnesium nitride with 7.73 g of water?

A) 0.0378
B) 0.113
C) 0.429
D) 4.57
E) 0.0756

Question 73

A compound is composed of only C, H, and O. The combustion of a 0.519- g sample of the compound yields 1.24 g of CO₂ and 0.255 g of H₂O. What is the empirical formula of the compound?

A) C₆H₆O
B) CH₃O
C) C₃H₃O
D) C₂H₆O₂
E) C₂H₆O₅

Question 74

Write the balanced equation for the reaction that occurs when methanol, CH₃OH (l), is burned in air. What is the coefficient of methanol in the balanced equation?

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

Question 75

A 2.25- g sample of magnesium nitrate, Mg(NO₃)₂, contains mol of this compound.

A) 0.0261
B) 65.8
C) 0.0152
D) 148.3
E) 38.4

Question 76

Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia:

A 9.3- g sample of hydrogen requires

Question 77

Determine the mass percent (to the hundredth's place) of H in sodium bicarbonate (NaHCO₃).

Question 78

A compound that is composed of only carbon and hydrogen contains 80.0% C and 20.0% H by mass. What is the empirical formula of the compound?

A) C₂H₆
B) C₂₀H₆₀
C) CH₄
D) C₇H₂₀
E) CH₃

Question 79

A compound contains 40.0% C, 6.71% H, and 53.29% O by mass. The molecular weight of the compound is 60.05 amu. The molecular formula of this compound is _ _.

A) C₂H₃O₄
B) CHO₂
C) C₂H₄O₂
D) C₂H₂O₄
E) CH₂O

Question 80

Lead (II) carbonate decomposes to give lead (II) oxide and carbon dioxide:

How many grams of lead (II) oxide will be produced by the decomposition of 2.50 g of lead (II) carbonate?

A) 0.00936
B) 0.41
C) 2.61
D) 2.09
E) 2.50