Deck 7: Mass Stoichiometry

Question 1

How many molecules of carbon monoxide, CO, comprise 2.34 moles?

A) 1.41 × 10²⁴
B) 2.57 × 10²³
C) 1.69 × 10²⁵
D) 2.15 × 10²²

Answer 1

1.41 × 10²⁴

Question 2

How many moles of KF are present in 15.2 grams of KF?

A) 0.262
B) 3.82
C) 6.02
D) 882

Answer 2

0.262

Question 3

How many moles of CO₂ are present in 88.0 grams of CO₂?

A) 0.636
B) 1.42
C) 0.88
D) 2.00

Answer 3

2.00

Question 4

How many atoms are present in a 0.300-mole sample of gold?

A) 4.98 × 10²⁵
B) 1.27 × 10¹⁵
C) 1.81 × 10²³
D) 6.02 × 10²³

Question 5

What is the mass of 1.5 × 10²¹ silicon atoms?

A) 0.0025 g
B) 4.21 × 10²² g
C) 0.070 g
D) 9.52 × 10²⁴ g

Question 6

A skunk's spray contains the foul-smelling compound butanethiol, C₄H₈S. What is the percent by mass of sulfur in this compound (to the nearest whole percent)?

A) 8%
B) 36%
C) 55%
D) 75%

Question 7

How many atoms are present in a 0.900-mole sample of gold?

A) 1.81 × 10²³
B) 1.50 × 10²⁴
C) 5.42 × 10²³
D) 6.02 × 10²³

Question 8

What is the formula mass, to the nearest whole number, for lithium nitrite, LiNO₂?

A) 7 amu
B) 44 amu
C) 37 amu
D) 53 amu

Question 9

How many moles of CO₂ are present in 56.0 grams of CO₂?

A) 0.786
B) 2.00
C) 0.560
D) 1.27

Question 10

What is the mass of 1.6 × 10²¹ argon atoms?

A) 0.11 g
B) 0.0027 g
C) 39.4 g
D) 5.11 × 10²² g

Question 11

What is the mass of 3.00 moles of CS₂?

A) 25.4 g
B) 229 g
C) 0.0394 g
D) 1.81 × 10²⁴ g

Question 12

A skunk's spray contains the foul-smelling compound butanethiol, C₄H₈S. What is the percent by mass of carbon in this compound (to the nearest whole percent)?

A) 8%
B) 31%
C) 55%
D) 75%

Question 13

How many atoms are present in a 0.600-mole sample of gold?

A) 3.61 × 10²³
B) 1.18 × 10¹⁵
C) 9.97 × 10²⁵
D) 6.02 × 10²³

Question 14

What is the mass of 2.00 moles of CS₂?

A) 38.1 g
B) 152 g
C) 0.0262 g
D) 1.20 × 10²⁴ g

Question 15

What is the formula mass, to the nearest whole number, for sodium nitrite, NaNO₂?

A) 23 amu
B) 53 amu
C) 69 amu
D) 83 amu

Question 16

What is the mass of 3.20 moles of KF?

A) 18.2 g
B) 0.055 g
C) 186 g
D) 1.93 × 10²⁴ g

Question 17

What is the formula mass, to the nearest whole number, for potassium nitrite, KNO₂?

A) 39 amu
B) 69 amu
C) 85 amu
D) 153 amu

Question 18

Lithium carbonate, Li₂CO₃, is commonly used to treat bipolar disorder. What is the percent by mass of carbon in this compound (to the nearest whole percent)?

A) 8%
B) 16%
C) 58%
D) 75%

Question 19

How many molecules of carbon dioxide, CO₂, comprise 1.22 moles?

A) 7.34 × 10²³
B) 4.93 × 10²³
C) 2.65 × 10²⁵
D) 1.37 × 10²²

Question 20

How many molecules of water, H₂O, comprise 2.07 moles?

A) 1.25 × 10²⁴
B) 2.91 × 10²³
C) 1.08 × 10²⁵
D) 3.34 × 10²²

Question 21

Consider the following reaction: Fe + Br₂ $\rightarrow$ FeBr₂
If 44.2 grams of iron react with an excess of bromine gas, what mass of FeBr₂ can form?
(FeBr₂ = 215.65 g/mol)

A) 171 g
B) 3.67 × 10^-3 g
C) 11.4 g
D) 272 g

Question 22

Based on the following balanced equation, how many moles of CO₂ will be produced along with 6 moles of water?
CH₄ (g) + 2 O₂ (g) $\rightarrow$ CO₂ (g) + 2 H₂O (g)

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

Question 23

In this reaction, BaCO₃ is the:
BaCl₂ (aq) + Na₂CO₃ (aq) $\rightarrow$ BaCO₃ (s) + 2 NaCl (aq)

A) excess reagent.
B) reactant.
C) dissociated compound.
D) precipitate.

Question 24

How many molecules of water, H₂O, comprise 3.64 grams?

A) 1.22 × 10²³
B) 3.95 × 10²⁵
C) 2.98 × 10²⁴
D) 8.22 × 10²⁴

Question 25

Based on the following balanced equation, how many moles of SF₆ can form from the combination of 6 moles of S and 15 moles of F₂?
S + 3 F₂ $\rightarrow$ SF₆

A) 5
B) 6
C) 15
D) 20

Question 26

Based on the following balanced equation, how many moles of H₂O can form from the reaction of 6 moles of CH₄?
CH₄ (g) + 2 O₂ (g) $\rightarrow$ CO₂ (g) + 2 H₂O (g)

A) 6
B) 3
C) 12
D) 18

Question 27

In this reaction, the limiting reagent is:

A) Br₂.
B) AlBr₃.
C) Al.
D) H₂O.

Question 28

Consider the following reaction: Fe + Br₂ $\rightarrow$ FeBr₂
If 38.6 grams of iron react with an excess of bromine gas, what mass of FeBr₂ can form?
(FeBr₂ = 215.65 g/mol)

A) 149 g
B) 3.20 × 10^-3 g
C) 10.0 g
D) 312 g

Question 29

How many molecules of carbon dioxide, CO₂, comprise 2.55 grams?

A) 3.49 × 10²²
B) 6.76 × 10²⁵
C) 1.04 × 10²⁵
D) 2.86 × 10²³

Question 30

In this reaction, the symbol (aq) after BaCl₂ means that it is:
BaCl₂ (aq) + Na₂CO₃ (aq) $\rightarrow$ BaCO₃ (s) + 2 NaCl (aq)

A) the excess reagent.
B) an ionic compound.
C) a reactant.
D) dissolved in water.

Question 31

What is the mass of 1.6 × 10²¹ neon atoms?

A) 0.054 g
B) 0.0027 g
C) 19 g
D) 3.2 × 10²² g

Question 32

Consider the following reaction: 4 Fe + 3 O₂ $\rightarrow$ 2 Fe₂O₃
If 44.2 grams of iron react with an excess of oxygen gas, what mass of Fe₂O₃ can form?
(Fe₂O₃ = 159.70 g/mol)

A) 63.2 g
B) 253 g
C) 15.5 g
D) 126 g

Question 33

In this reaction, ZnCO₃ is the:
ZnBr₂ (aq) + K₂CO₃ (aq) $\rightarrow$ 2 KBr (aq) + ZnCO₃ (s)

A) precipitate.
B) reactant.
C) dissociated compound.
D) excess reagent.

Question 34

Based on the following balanced equation, how many moles of SF₆ can form from the combination of 11 moles of S and 18 moles of F₂?
S + 3 F₂ $\rightarrow$ SF₆

A) 6
B) 11
C) 18
D) 29

Question 35

Based on the following balanced equation, how many moles of SF₆ can form from the combination of 5 moles of S and 18 moles of F₂?
S + 3 F₂ $\rightarrow$ SF₆

A) 6
B) 5
C) 18
D) 23

Question 36

Consider the following reaction: Fe + Br₂ $\rightarrow$ FeBr₂
If 53.2 grams of iron react with an excess of bromine gas, what mass of FeBr₂ can form?
(FeBr₂ = 215.65 g/mol)

A) 226 g
B) 13.8 g
C) 205 g
D) 4.41 × 10^-3 g

Question 37

How many molecules of carbon monoxide, CO, comprise 4.82 grams?

A) 1.04 × 10²³
B) 8.13 × 10²⁵
C) 3.50 × 10²⁴
D) 2.24 × 10²²

Question 38

In this reaction, the excess reagent is:

A) Br₂.
B) AlBr₃.
C) Al.
D) H₂O.

Question 39

Based on the following balanced equation, how many moles of O₂ will be needed to react completely with of 4 moles of CH₄?
CH₄ (g) + 2 O₂ (g) $\rightarrow$ CO₂ (g) + 2 H₂O (g)

A) 2
B) 4
C) 8
D) 12

Question 40

In this reaction, the symbol (aq) after ZnBr₂ means that it is:
ZnBr₂ (aq) + K₂CO₃ (aq) $\rightarrow$ 2 KBr (aq) + ZnCO₃ (s)

A) the excess reagent.
B) an ionic compound.
C) a reactant.
D) dissolved in water.

Question 41

Consider the following reaction: 4 Fe + 3 O₂ $\rightarrow$ 2 Fe₂O₃
If 44.2 grams of oxygen react with an excess of iron, what mass of Fe₂O₃ can form?
(Fe₂O₃ = 159.70 g/mol)

A) 147 g
B) 331 g
C) 294 g
D) 221 g

Question 42

A chemist carries out this reaction in the laboratory using 4.31 grams of zinc and an excess of sulfur: Zn + S $\rightarrow$ ZnS
From the balanced equation, she calculates that she should obtain 6.41 grams of zinc sulfide. However, she isolates only 5.85 grams of product. What is her percent yield for this reaction?

A) 2.1%
B) 67.2%
C) 109.6%
D) 91.3%

Question 43

Consider the following reaction: 4 Fe + 3 O₂ $\rightarrow$ 2 Fe₂O₃
How many grams of oxygen gas are needed to react completely with 44.2 grams of iron?

A) 19.0 g
B) 101 g
C) 12.7 g
D) 25.3 g

Question 44

A chemist carries out this reaction in the laboratory using 4.31 grams of zinc and an excess of sulfur: Zn + S $\rightarrow$ ZnS
From the balanced equation, she calculates that she should obtain 6.41 grams of zinc sulfide. However, she isolates only 5.01 grams of product. What is her percent yield for this reaction?

A) 67.2%
B) 86.0%
C) 78.2%
D) 128%