Deck 7: Mass Stoichiometry

Question 1

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

Answer 1

85 amu

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 56.0 grams of CO₂?

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

Answer 3

1.27

Question 4

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 5

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 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

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 8

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

Question 9

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 10

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 11

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 12

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 13

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 14

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

Question 15

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 16

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 17

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 18

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 19

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 20

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 21

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 22

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 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

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 25

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 26

In this reaction,the limiting reagent is:

A) Br₂.
B) AlBr₃.
C) Al.
D) H₂O.

Question 27

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 28

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 29

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 30

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 31

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 32

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 33

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 34

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 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

In this reaction,the excess reagent is:

A) Br₂.
B) AlBr₃.
C) Al.
D) H₂O.

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

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

Question 39

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 40

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 41

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%

Question 42

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 43

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 44

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