Chapter 3 1 When the following equation is balanced, the coefficients are

Chemistry: The Central Science, 13e (Brown et al.)

Chapter 3 Stoichiometry: Calculations with Chemical Formulas and Equations

3.1 Multiple-Choice Questions

1) When the following equation is balanced, the coefficients are ________.

C8H18 + O2 → CO2 + H2O

A) 2, 3, 4, 4

B) 1, 4, 8, 9

C) 2, 12, 8, 9

D) 4, 4, 32, 36

E) 2, 25, 16, 18

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

A) C + O2 → CO2

B) 2Mg + O2 → 2MgO

C) 2N2 + 3H2 → 2NH3

D) CaO + H2O → Ca(OH)2

E) 2CH4 + 4O2 → 2CO2 + 4H2O

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

A) oxygen

B) nitrogen

C) carbon dioxide

D) water

E) argon

4) When a hydrocarbon burns in air, a component produced is ________.

A) oxygen

B) nitrogen

C) carbon

D) water

E) argon

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

A) NH4Cl → NH3 + HCl

B) 2Mg + O2 → 2MgO

C) 2N2 + 3H2 → 2NH3

D) 2CH4 + 4O2 → 2CO2 + 4H2O

E) Cd(NO3)2 + Na2S → CdS + 2NaNO3

6) Which one of the following substances is the product of this combination reaction?

Al (s) + I2 (s) → ________

A) AlI2

B) AlI

C) AlI3

D) Al2I3

E) Al3I2

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

A) They are inflated as a result of a decomposition reaction.

B) They are loaded with sodium azide initially.

C) The gas used for inflating them is oxygen.

D) The two products of the decomposition reaction are sodium and nitrogen.

E) A gas is produced when the air bag activates.

8) The reaction used to inflate automobile airbags ________.

A) produces sodium gas

B) is a combustion reaction

C) is a combination reaction

D) violates the law of conservation of mass

E) is a decomposition reaction

9) Which of the following are combination reactions?

1) CH4 (g) + O2 (g) → CO2 (g) + H2O (l)

2) CaO (s) + CO2 (g) → CaCO3 (s)

3) Mg (s) + O2 (g) → MgO (s)

4) PbCO3 (s) → PbO (s) + CO2 (g)

A) 1, 2, and 3

B) 2 and 3

C) 1, 2, 3, and 4

D) 4 only

E) 2, 3, and 4

10) Which of the following are combustion reactions?

1) CH4 (g) + O2 (g) → CO2 (g) + H2O (l)

2) CaO (s) + CO2 (g) → CaCO3 (s)

3) PbCO3 (s) → PbO (s) + CO2 (g)

4) CH3OH (l) + O2 (g) → CO2 (g) + H2O (l)

A) 1 and 4

B) 1, 2, 3, and 4

C) 1, 3, and 4

D) 2, 3, and 4

E) 3 and 4

11) Which of the following are decomposition reactions?

1) CH4 (g) + O2 (g) → CO2 (g) + H2O (l)

2) CaO (s) + CO2 (g) → CaCO3 (s)

3) Mg (s) + O2 (g) → MgO (s)

4) PbCO3 (s) → PbO (s) + CO2 (g)

A) 1, 2, and 3

B) 4 only

C) 1, 2, 3, and 4

D) 2 and 3

E) 2, 3, and 4

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

A) 107.11

B) 43.03

C) 109.10

D) 123.11

E) 3.06

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

A) 107.09

B) 255.08

C) 242.18

D) 294.18

E) 333.08

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

A) 159.87

B) 223.87

C) 331.73

D) 339.86

E) 175.87

15) The formula weight of ammonium sulfate ((NH4)2SO4), rounded to the nearest integer, is ________

amu.

A) 100

B) 118

C) 116

D) 132

E) 264

16) The molecular weight of the acetic acid (CH3CO2H), rounded to the nearest integer, is ________ amu.

A) 60

B) 48

C) 44

D) 32

17) The formula weight of a substance is ________.

A) identical to the molar mass

B) the same as the percent by mass weight

C) determined by combustion analysis

D) the sum of the atomic weights of each atom in its chemical formula

E) the weight of a sample of the substance

18) The formula weight of calcium nitrate (Ca(NO3)2), rounded to one decimal place, is ________ amu.

A) 102.1

B) 164.0

C) 204.2

D) 150.1

E) 116.1

19) The formula weight of magnesium fluoride (MgF2), rounded to one decimal place, is ________ amu.

A) 86.6

B) 43.3

C) 62.3

D) 67.6

E) 92.9

20) The formula weight of lead nitrate (Pb(NO3)2) is ________ amu.

A) 269.2

B) 285.2

C) 317.2

D) 331.2

E) 538.4

21) The mass % of C in methane (CH4) is ________.

A) 25.13

B) 133.6

C) 74.87

D) 92.26

E) 7.743

22) The mass % of H in methane (CH4) is ________.

A) 25.13

B) 4.032

C) 74.87

D) 92.26

E) 7.743

23) The mass % of F in the binary compound KrF2 is ________.

A) 18.48

B) 45.38

C) 68.80

D) 81.52

E) 31.20

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

A) 4.67

B) 9.34

C) 9.90

D) 4.95

E) 12.67

25) Calculate the percentage by mass of lead in Pb(NO3)2.

A) 38.6

B) 44.5

C) 62.6

D) 65.3

E) 71.2

26) Calculate the percentage by mass of lead in PbCO3.

A) 17.96

B) 22.46

C) 73.05

D) 77.54

E) 89.22

27) Calculate the percentage by mass of oxygen in Pb(NO3)2.

A) 9.7

B) 14.5

C) 19.3

D) 29.0

E) 33.4

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

A) 23.63

B) 11.82

C) 25.05

D) 12.53

E) 18.09

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

A) 1.558

B) 1.008

C) 0.672

D) 0.034

E) 2.016

30) One mole of ________ contains the largest number of atoms.

A) S8

B) C10H8

C) Al2(SO4)3

D) Na3PO4

E) Cl2

31) One mole of ________ contains the smallest number of atoms.

A) S8

B) C10H8

C) Al2(SO4)3

D) Na3PO4

E) NaCl

32) One million argon atoms is ________ mol (rounded to two significant figures) of argon atoms.

A) 3.0

B) 1.7 × 10–18

C) 6.0 × 1023

D) 1.0 × 10-6

E) 1.0 × 106

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

A) 5.00 × 1024

B) 3.00

C) 2.90 × 1025

D) 1.81 × 1024

E) 4.00

34) A 30.5 gram sample of glucose (C6H12O6) contains ________ mol of glucose.

A) 0.424

B) 0.169

C) 5.90

D) 2.36

E) 0.136

35) A sample of CH2F2 with a mass of 19 g contains ________ atoms of F.

A) 2.2 × 1023

B) 38

C) 3.3 × 1024

D) 4.4 ×1023

E) 9.5

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

A) 5.32 × 10–23

B) 1.00

C) 1.88 × 1022

D) 6.02 × 1023

E) 32.0

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

A) 3.5

B) 1.5 × 1023

C) 3.0 × 1023

D) 1.8

E) 2

38) 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) 4.76 × 1022

B) 3.43 × 1025

C) 2.11 × 1022

D) 1.59 × 1025

E) 6.02 × 1023

11

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

A) 12

B) 6.02 × 1023

C) 7.22 × 1024

D) 5.79 × 1022

E) 8.01 × 10-3

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

A) 15.0

B) 1.00 × 1024

C) 4.46 × 1021

D) 1.67

E) 2.76 × 10–24

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

A) 1.08 × 1023

B) 6.02 × 1024

C) 1.80 × 1024

D) 1.08 × 1024

E) 6.02 × 1023

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

A) 1.80 × 1023

B) 6.02 × 1024

C) 6.02 × 1023

D) 1.08 × 1024

E) 1.08 × 1023

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

12

A) 5.206 × 1024

B) 3.134 × 1025

C) 7.122 × 1023

D) 8.648 × 10–23

E) 1.424 × 1024

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

A) 1.424 × 1024

B) 6.022 × 1023

C) 1.204 × 1024

D) 5.088 × 1023

E) 1.018 × 1024

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

A) 5.890 × 10-7

B) 2.945 × 10-7

C) 1.473 × 10-7

D) 8.836 × 10-7

E) 9.817 × 10-8

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

A) 3.121 × 10-5

B) 1.011 × 10-5

C) 1.517 × 10-5

D) 9.100 × 10-5

E) 6.066 × 10-5

47) The compound responsible for the characteristic smell of garlic is allicin, C6H10OS2. The mass of 1.00

mol of allicin, rounded to the nearest integer, is ________ g.

A) 34

B) 162

C) 86

D) 61

E) 19

48) The molecular formula of aspartame, the generic name of NutraSweet®, is C14H18N2O5. The molar

mass of aspartame, rounded to the nearest integer, is ________ g.

A) 24

B) 156

C) 294

D) 43

E) 39

49) There are ________ oxygen atoms in 30 molecules of C20H42S3O2.

A) 6.0 × 1023

B) 1.8 × 1025

C) 3.6 × 1025

D) 1.2 × 1024

E) 60

50) A nitrogen oxide is 63.65% by mass nitrogen. The molecular formula could be ________.

A) NO

B) NO2

C) N2O

D) N2O4

E) either NO2 or N2O4

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

A) SO

B) SO2

C) S2O

D) S2O4

E) either SO2 or S2O4

52) Which hydrocarbon pair below has identical mass percentage of C?

A) C3H4 and C3H6

B) C2H4 and C3H4

C) C2H4 and C4H2

D) C2H4 and C3H6

E) none of the above

53) Propane (C3H8) reacts with oxygen in the air to produce carbon dioxide and water. In a particular

experiment, 38.0 grams of carbon dioxide are produced from the reaction of 22.05 grams of propane with

excess oxygen. What is the % yield in this reaction?

A) 38.0

B) 57.6

C) 66.0

D) 86.4

E) 94.5

3.2 Bimodal Questions

1) When the following equation is balanced, the coefficients are ________.

NH3 (g) + O2 (g) → NO2 (g) + H2O (g)

A) 1, 1, 1, 1

B) 4, 7, 4, 6

C) 2, 3, 2, 3

D) 1, 3, 1, 2

E) 4, 3, 4, 3

2) When the following equation is balanced, the coefficients are ________.

Al(NO3)3 + Na2S → Al2S3 + NaNO3

A) 2, 3, 1, 6

B) 2, 1, 3, 2

C) 1, 1, 1, 1

D) 4, 6, 3, 2

E) 2, 3, 2, 3

3) When the following equation is balanced, the coefficient of H2 is ________.

K (s) + H2O (l) → KOH (aq) + H2 (g)

A) 1

B) 2

C) 3

D) 4

E) 5

4) When the following equation is balanced, the coefficient of Al is ________.

Al (s) + H2O (l) → Al(OH)3 (s) + H2 (g)

A) 1

B) 2

C) 3

D) 5

E) 4

5) When the following equation is balanced, the coefficient of H2O is ________.

Ca (s) + H2O (l) → Ca(OH)2 (aq) + H2 (g)

A) 1

B) 2

C) 3

D) 5

E) 4

6) When the following equation is balanced, the coefficient of Al2O3 is ________.

Al2O3 (s) + C (s) + Cl2 (g) → AlCl3 (s) + CO (g)

A) 1

B) 2

C) 3

D) 4

E) 5

7) When the following equation is balanced, the coefficient of H2S is ________.

FeCl3 (aq) + H2S (g) → Fe2S3 (s) + HCl (aq)

A) 1

B) 2

C) 3

D) 5

E) 4

8) When the following equation is balanced, the coefficient of HCl is ________.

CaCO3 (s) + HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l)

A) 1

B) 2

C) 3

D) 4

E) 0

9) When the following equation is balanced, the coefficient of HNO3 is ________.

HNO3 (aq) + CaCO3 (s) → Ca(NO3)2 (aq) + CO2 (g) + H2O (l)

A) 1

B) 2

C) 3

D) 5

E) 4

10) When the following equation is balanced, the coefficient of H3PO4 is ________.

H3PO4 (aq) + NaOH (aq) → Na3PO4 (aq) + H2O (l)

A) 1

B) 2

C) 3

D) 4

E) 0

11) When the following equation is balanced, the coefficient of C3H8O3 is ________.

C3H8O3 (g) + O2 (g) → CO2 (g) + H2O (g)

A) 1

B) 2

C) 3

D) 7

E) 5

12) When the following equation is balanced, the coefficient of O2 is ________.

C2H4O (g) + O2 (g) → CO2 (g) + H2O (g)

A) 2

B) 3

C) 4

D) 5

E) 1

13) When the following equation is balanced, the coefficient of H2 is ________.

CO (g) + H2 (g) → H2O (g) + CH4 (g)

A) 1

B) 2

C) 3

D) 4

E) 0

14) When the following equation is balanced, the coefficient of H2SO4 is ________.

H2SO4 (aq) + NaOH (aq) → Na2SO4 (aq) + H2O (l)

A) 1

B) 2

C) 3

D) 4

E) 0.5

15) When the following equation is balanced, the coefficient of water is ________.

K (s) + H2O (l) → KOH (aq) + H2 (g)

A) 1

B) 2

C) 3

D) 4

E) 5

16) When the following equation is balanced, the coefficient of hydrogen is ________.

K (s) + H2O (l) → KOH (aq) + H2 (g)

A) 1

B) 2

C) 3

D) 4

E) 5

17) When the following equation is balanced, the coefficient of oxygen is ________.

PbS (s) + O2 (g) → PbO (s) + SO2 (g)

A) 1

B) 3

C) 2

D) 4

E) 5

18) When the following equation is balanced, the coefficient of sulfur dioxide is ________.

PbS (s) + O2 (g) → PbO (s) + SO2 (g)

A) 5

B) 1

C) 3

D) 2

E) 4