Question 1

Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO3 are produced by the reaction of 5.0 grams of O2 with 6.0 grams of S. What is the % yield of SO3 in this experiment? S (s) + O2 (g) → SO3 (g) (not balanced)

Accepted Answer

A)  32
B)  63
C)  75
D)  95
E)  99

Question 2

The combustion of ammonia in the presence of excess oxygen yields NO2 and H2O: 4 NH3 (g) + 7 O2 (g) → 4 NO2 (g) + 6 H2O (g) 
The combustion of 43.9 g of ammonia produces __________ g of NO2.

Accepted Answer

A)  2.58
B)  178
C)  119
D)  0.954
E)  43.9

Question 3

Water can be formed from the stoichiometric reaction of hydrogen with oxygen:
2 H2 (g)+ O2 (g)→ 2 H2O (g)
A complete reaction of 5.0 g of O2 with excess hydrogen produces __________ g of H2O.

Accepted Answer

Question 4

There are __________ hydrogen atoms in 25 molecules of C4H4S2.

Accepted Answer

A)  25
B)  3.8 × 1024
C)  6.0 × 1025
D)  100
E)  1.5 × 1025

Question 5

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

Accepted Answer

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

Question 6

When the following equation is balanced, the coefficient of C3H8O3 is __________. C3H8O3 (g) + O2 (g) → CO2 (g) + H2O (g)

Accepted Answer

A)  1
B)  2
C)  3
D)  7
E)  5

Question 7

What is the maximum mass in grams of NH3 that can be produced by the reaction of 1.0 g of N2 with 3.0 g of H2 via the equation below? N2 (g) + H2 (g) → NH3 (g) (not balanced)

Accepted Answer

A)  2.0
B)  1.2
C)  0.61
D)  17
E)  4.0

Question 8

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

Accepted Answer

A)  38.6
B)  44.5
C)  62.6
D)  65.3
E)  71.2

Question 9

Calcium carbide (CaC2) reacts with water to produce acetylene (C2H2) : CaC2 (s) + 2 H2O (g) → Ca(OH) 2 (s) + C2H2 (g) 
Production of 13 g of C2H2 requires consumption of __________ g of H2O.

Accepted Answer

A)  4.5
B)  9.0
C)  18
D)  4.8 × 102
E)  4.8 × 10-2

Question 10

When the following equation is balanced, the coefficient of dinitrogen pentoxide is __________. N2O5 (g) + H2O (l) → HNO3 (aq)

Accepted Answer

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

Question 11

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

Accepted Answer

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

Question 12

Calculate the percentage by mass of hydrogen in PtCl2(N H3) 2

Accepted Answer

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

Question 13

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

Accepted Answer

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

Question 14

Which hydrocarbon pair below have identical mass percentage of C?

Accepted Answer

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

Question 15

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

Accepted Answer

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

Question 16

Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia: N2 (g) + 3 H2 (g) → 2NH3 (g) 
If the reaction yield is 87.5%, how many moles of N2 are needed to produce 3.00 mol of NH3?.

Accepted Answer

A)  0.166
B)  1.00
C)  1.5
D)  1.71
E)  2.32

Question 17

If the reaction yield is 94.4%, what mass in grams of hydrogen is produced by the reaction of 4.73 g of magnesium with 1.83 g of water? Mg (s) + 2 H2O (l) → Mg(OH) 2 (s) + H2 (g)

Accepted Answer

A)  0.0962
B)  0.0162
C)  0.0485
D)  0.219
E)  0.204

Question 18

When the following equation is balanced, the coefficient of Al is __________. Al (s) + H2O (l) → Al(OH) 3 (s) + H2 (g)

Accepted Answer

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

Question 19

A 3.92-g sample of magnesium nitrate, Mg(NO3) 2, contains __________ mol of this compound.

Accepted Answer

A)  2.32
B)  1.65
C)  0.111
D)  0.0529
E)  0.0264

Question 20

A compound contains 38.7% K, 13.9% N, and 47.4% O by mass. What is the empirical formula of the compound?

Accepted Answer

A)  KNO3
B)  K2N2O3
C)  KNO2
D)  K2NO3
E)  K4NO5

Exam 3: Stoichiometry: Calculations With Chemical Formulas and Equations

Water can be formed from the stoichiometric reaction of hydrogen with oxygen: 2 H2 (g)+ O2 (g)→ 2 H2O (g) A complete reaction of 5.0 g of O2 with excess hydrogen produces __________ g of H2O.

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

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A 3.92-g sample of magnesium nitrate, Mg(NO3) 2, contains __________ mol of this compound.

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When the following equation is balanced, the coefficient of dinitrogen pentoxide is __________. N2O5 (g) + H2O (l) → HNO3 (aq)

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What is the maximum mass in grams of NH3 that can be produced by the reaction of 1.0 g of N2 with 3.0 g of H2 via the equation below? N2 (g) + H2 (g) → NH3 (g) (not balanced)

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There are __________ hydrogen atoms in 25 molecules of C4H4S2.

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Which hydrocarbon pair below have identical mass percentage of C?

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Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia: N2 (g) + 3 H2 (g) → 2NH3 (g) If the reaction yield is 87.5%, how many moles of N2 are needed to produce 3.00 mol of NH3?.

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Calculate the percentage by mass of hydrogen in PtCl2(N H3) 2

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Calcium carbide (CaC2) reacts with water to produce acetylene (C2H2) : CaC2 (s) + 2 H2O (g) → Ca(OH) 2 (s) + C2H2 (g) Production of 13 g of C2H2 requires consumption of __________ g of H2O.

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If the reaction yield is 94.4%, what mass in grams of hydrogen is produced by the reaction of 4.73 g of magnesium with 1.83 g of water? Mg (s) + 2 H2O (l) → Mg(OH) 2 (s) + H2 (g)

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

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

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When the following equation is balanced, the coefficient of Al is __________. Al (s) + H2O (l) → Al(OH) 3 (s) + H2 (g)

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The combustion of ammonia in the presence of excess oxygen yields NO2 and H2O: 4 NH3 (g) + 7 O2 (g) → 4 NO2 (g) + 6 H2O (g) The combustion of 43.9 g of ammonia produces __________ g of NO2.

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Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO3 are produced by the reaction of 5.0 grams of O2 with 6.0 grams of S. What is the % yield of SO3 in this experiment? S (s) + O2 (g) → SO3 (g) (not balanced)

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

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When the following equation is balanced, the coefficient of C3H8O3 is __________. C3H8O3 (g) + O2 (g) → CO2 (g) + H2O (g)

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A compound contains 38.7% K, 13.9% N, and 47.4% O by mass. What is the empirical formula of the compound?

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

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Water can be formed from the stoichiometric reaction of hydrogen with oxygen: 2 H₂ (g)+ O₂ (g)→ 2 H₂O (g) A complete reaction of 5.0 g of O₂ with excess hydrogen produces __________ g of H₂O.

Correct Answer
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The mass % of H in methane (CH₄) is __________.

Correct Answer
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A 3.92-g sample of magnesium nitrate, Mg(NO₃) ₂, contains __________ mol of this compound.

Correct Answer
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When the following equation is balanced, the coefficient of dinitrogen pentoxide is __________. N₂O₅ (g) + H₂O (l) → HNO₃ (aq)

Correct Answer
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What is the maximum mass in grams of NH3 that can be produced by the reaction of 1.0 g of N₂ with 3.0 g of H₂ via the equation below? N₂ (g) + H₂ (g) → NH₃ (g) (not balanced)

Correct Answer
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There are __________ hydrogen atoms in 25 molecules of C₄H₄S₂.

Correct Answer
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Correct Answer
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Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia: N₂ (g) + 3 H₂ (g) → 2NH₃ (g) If the reaction yield is 87.5%, how many moles of N₂ are needed to produce 3.00 mol of NH₃?.

Correct Answer
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Calculate the percentage by mass of hydrogen in PtCl₂(N H₃) ₂

Correct Answer
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Calcium carbide (CaC₂) reacts with water to produce acetylene (C₂H₂) : CaC₂ (s) + 2 H₂O (g) → Ca(OH) ₂ (s) + C₂H₂ (g) Production of 13 g of C₂H₂ requires consumption of __________ g of H₂O.

Correct Answer
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If the reaction yield is 94.4%, what mass in grams of hydrogen is produced by the reaction of 4.73 g of magnesium with 1.83 g of water? Mg (s) + 2 H₂O (l) → Mg(OH) ₂ (s) + H₂ (g)

Correct Answer
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The mass % of C in methane (CH₄) is __________.

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

Correct Answer
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When the following equation is balanced, the coefficient of Al is __________. Al (s) + H₂O (l) → Al(OH) ₃ (s) + H₂ (g)

Correct Answer
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The combustion of ammonia in the presence of excess oxygen yields NO₂ and H₂O: 4 NH₃ (g) + 7 O₂ (g) → 4 NO₂ (g) + 6 H₂O (g) The combustion of 43.9 g of ammonia produces __________ g of NO₂.

Correct Answer
verified

Sulfur and oxygen react to produce sulfur trioxide. In a particular experiment, 7.9 grams of SO₃ are produced by the reaction of 5.0 grams of O₂ with 6.0 grams of S. What is the % yield of SO₃ in this experiment? S (s) + O₂ (g) → SO₃ (g) (not balanced)

Correct Answer
verified

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

Correct Answer
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When the following equation is balanced, the coefficient of C₃H₈O₃ is __________. C₃H₈O₃ (g) + O₂ (g) → CO₂ (g) + H₂O (g)

Correct Answer
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Correct Answer
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Correct Answer
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