Question 1

The first step in the Ostwald process for producing nitric acid is as follows: 4NH3(g)  + 5O2(g)  → 4NO(g)  + 6H2O(g) .
If the reaction of 15.0 g of ammonia with 15.0 g of oxygen gas yields 8.70 g of nitric oxide, what is the percent yield of this reaction?

Accepted Answer

A)   29.0%
B)   32.9%
C)   49.5%
D)   61.8%
E)   77.3%F) A) and C)
G) C) and D)

Question 2

What is the empirical formula for a 100-g sample containing 87.42 g of nitrogen and 12.58 g of hydrogen?

Accepted Answer

A)   NH
B)   N2H
C)   NH2
D)   NH3
E)   N7HF) A) and E)
G) A) and D)

Question 3

What is the maximum number of grams of ammonia, NH3, which can be obtained from the reaction of 10.0 g of H2 and 80.0 g of N2? N2 + 3H2 → 2NH3

Accepted Answer

A)   34.1 g
B)   48.6 g
C)   56.3 g
D)   90.0 g
E)   97.3 gF) A) and D)
G) B) and E)

Question 4

Sulfur trioxide can react with atmospheric water vapor to form sulfuric acid that falls as acid rain. Calculate the mass in grams of 3.65 × 1020 molecules of sulfur trioxide.

Accepted Answer

A)   6.06 × 10-4 g
B)   2.91 × 10-2 g
C)   4.85 × 10-2 g
D)   20.6 g
E)   1650 gF) B) and C)
G) C) and E)

Question 5

What is the percent sodium in sodium carbonate?

Accepted Answer

A)   43.4%
B)   11.3%
C)   45.3%
D)   27.7%
E)   21.7%F) C) and D)
G) A) and D)

Question 6

If 119.3 g of PCl5 are formed from the reaction of 61.3 g Cl2 with excess PCl3, what is the percent yield? PCl3(g)  + Cl2(g)  → PCl5(g)

Accepted Answer

A)   94.6%
B)   66.3%
C)   57.3%
D)   51.3%
E)   48.6%F) D) and E)
G) None of the above

Question 7

Aluminum reacts with bromine to form aluminum bromide (used as an acid catalyst in organic synthesis) . Al(s)  + Br2(l)  → Al2Br6(s)  [unbalanced]
How many moles of Al are needed to form 2.43 mol of Al2Br6?

Accepted Answer

A)   7.29 mol
B)   4.86 mol
C)   2.43 mol
D)   1.62 mol
E)   1.22 molF) A) and B)
G) C) and D)

Question 8

How many grams of calcium metal is required to react with 7.75 g water to produce calcium hydroxide and hydrogen gas?

Accepted Answer

A)   8.62 g
B)   34.5 g
C)   4.31 g
D)   40.1 g
E)   17.2 gF) A) and B)
G) A) and C)

Question 9

The molecular formula is a whole number multiple of the empirical formula.

Accepted Answer

A) True 
 B)False

Question 10

Calculate the formula mass of ammonium arsenate, (NH4) 3AsO4.

Accepted Answer

A)   417.80 amu
B)   193.05 amu
C)   165.02 amu
D)   156.96 amu
E)   108.96 amuF) None of the above
G) A) and B)

Question 11

When octane (C8H18)  is burned in a particular internal combustion engine, the yield of products (carbon dioxide and water)  is 93%. What mass of carbon dioxide will be produced in this engine when 15.0 g of octane is burned with 15.0 g of oxygen gas?

Accepted Answer

A)   13 g
B)   12 g
C)   21 g
D)   54 g
E)   43 gF) A) and C)
G) B) and E)

Question 12

Calculate the formula mass of potassium permanganate, KMnO4.

Accepted Answer

A)   149.91 amu
B)   79.41 amu
C)   127.41 amu
D)   158.04 amu
E)   174.04 amuF) A) and E)
G) D) and E)

Question 13

A certain compound of bromine and fluorine is used to make UF6, which is an important chemical in the processing and reprocessing of nuclear fuel. The compound contains 58.37 mass percent bromine. What is its empirical formula?

Accepted Answer

A)   BrF
B)   BrF2
C)   Br2F3
D)   Br3F
E)   BrF3F) C) and D)
G) D) and E)

Question 14

What is the coefficient of O2 when the following equation is properly balanced with the smallest set of whole numbers? ________ C2H4 + ________ O2 → ________ CO2 + ________ H2O

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   6F) C) and E)
G) A) and B)

Question 15

Many compounds can be represented with the same empirical formula.

Accepted Answer

A) True 
 B)False

Question 16

What is the theoretical yield of vanadium, in moles, that can be produced by the reaction of 2.0 mole of V2O5 with 6.0 mole of calcium based on the following chemical equation? V2O5(s)  + 5Ca(l)  → 2V(l)  + 5CaO(s)

Accepted Answer

A)   1.0 mol
B)   1.6 mol
C)   2.0 mol
D)   2.4 mol
E)   4.0 molF) B) and C)
G) A) and D)

Question 17

The density of water is 1.00 g/mL at 4°C. How many water molecules are present in 6.25 mL of water at this temperature? (NA = 6.022 × 1023 mol-1)

Accepted Answer

A)   6.27 × 1023 molecules
B)   3.76 × 1024 molecules
C)   2.09 × 1023 molecules
D)   6.02 × 1023 molecules
E)   0.347 moleculesF) A) and B)
G) A) and E)

Question 18

Hydrochloric acid can be prepared by the following reaction: 2NaCl(s)  + H2SO4(aq)  → 2HCl(g)  + Na2SO4(s) 
What mass of HCl can be prepared from 2.00 mol H2SO4 and 150. g NaCl?

Accepted Answer

A)   2.57 g
B)   46.8 g
C)   93.6g
D)   146 g
E)   167gF) D) and E)
G) C) and D)

Question 19

Ammonia reacts with oxygen to form nitrogen monoxide and water. What is the theoretical yield and the percent yield if 17.25 g of nitrogen monoxide is produced when 21.50 g of ammonia and 26.85 g of oxygen react? (Show all your work)

Accepted Answer

Theoretical yield = ...

Question 20

What is the average mass, in grams, of one atom of iron? (NA = 6.022 × 1023 mol-1)

Accepted Answer

A)   6.02 × 1023 g
B)   1.66 × 10-24 g
C)   9.27 × 10-23 g
D)   55.85 g
E)   55.85 × 10-23 gF) B) and E)
G) A) and E)

Exam 3: Stoichiometry: Ratios of Combination

The density of water is 1.00 g/mL at 4°C. How many water molecules are present in 6.25 mL of water at this temperature? (NA = 6.022 × 1023 mol-1)

Correct AnswerverifiedShow Answer

If 119.3 g of PCl5 are formed from the reaction of 61.3 g Cl2 with excess PCl3, what is the percent yield? PCl3(g) + Cl2(g) → PCl5(g)

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Aluminum reacts with bromine to form aluminum bromide (used as an acid catalyst in organic synthesis) . Al(s) + Br2(l) → Al2Br6(s) [unbalanced] How many moles of Al are needed to form 2.43 mol of Al2Br6?

Correct AnswerverifiedShow Answer

The first step in the Ostwald process for producing nitric acid is as follows: 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g) . If the reaction of 15.0 g of ammonia with 15.0 g of oxygen gas yields 8.70 g of nitric oxide, what is the percent yield of this reaction?

Correct AnswerverifiedShow Answer

Many compounds can be represented with the same empirical formula.

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Calculate the formula mass of ammonium arsenate, (NH4) 3AsO4.

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Hydrochloric acid can be prepared by the following reaction: 2NaCl(s) + H2SO4(aq) → 2HCl(g) + Na2SO4(s) What mass of HCl can be prepared from 2.00 mol H2SO4 and 150. g NaCl?

Correct AnswerverifiedShow Answer

What is the average mass, in grams, of one atom of iron? (NA = 6.022 × 1023 mol-1)

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The molecular formula is a whole number multiple of the empirical formula.

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What is the coefficient of O2 when the following equation is properly balanced with the smallest set of whole numbers? ________ C2H4 + ________ O2 → ________ CO2 + ________ H2O

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Ammonia reacts with oxygen to form nitrogen monoxide and water. What is the theoretical yield and the percent yield if 17.25 g of nitrogen monoxide is produced when 21.50 g of ammonia and 26.85 g of oxygen react? (Show all your work)

Correct AnswerverifiedTheoretical yield = ...View AnswerShow Answer

Calculate the formula mass of potassium permanganate, KMnO4.

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Sulfur trioxide can react with atmospheric water vapor to form sulfuric acid that falls as acid rain. Calculate the mass in grams of 3.65 × 1020 molecules of sulfur trioxide.

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How many grams of calcium metal is required to react with 7.75 g water to produce calcium hydroxide and hydrogen gas?

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When octane (C8H18) is burned in a particular internal combustion engine, the yield of products (carbon dioxide and water) is 93%. What mass of carbon dioxide will be produced in this engine when 15.0 g of octane is burned with 15.0 g of oxygen gas?

Correct AnswerverifiedShow Answer

What is the theoretical yield of vanadium, in moles, that can be produced by the reaction of 2.0 mole of V2O5 with 6.0 mole of calcium based on the following chemical equation? V2O5(s) + 5Ca(l) → 2V(l) + 5CaO(s)

Correct AnswerverifiedShow Answer

A certain compound of bromine and fluorine is used to make UF6, which is an important chemical in the processing and reprocessing of nuclear fuel. The compound contains 58.37 mass percent bromine. What is its empirical formula?

Correct AnswerverifiedShow Answer

What is the empirical formula for a 100-g sample containing 87.42 g of nitrogen and 12.58 g of hydrogen?

Correct AnswerverifiedShow Answer

What is the percent sodium in sodium carbonate?

Correct AnswerverifiedShow Answer

What is the maximum number of grams of ammonia, NH3, which can be obtained from the reaction of 10.0 g of H2 and 80.0 g of N2? N2 + 3H2 → 2NH3

Correct AnswerverifiedShow Answer

The density of water is 1.00 g/mL at 4°C. How many water molecules are present in 6.25 mL of water at this temperature? (N_A = 6.022 × 10²³ mol^-1)

Correct Answer
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If 119.3 g of PCl₅ are formed from the reaction of 61.3 g Cl₂ with excess PCl₃, what is the percent yield? PCl₃(g) + Cl₂(g) → PCl₅(g)

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Aluminum reacts with bromine to form aluminum bromide (used as an acid catalyst in organic synthesis) . Al(s) + Br₂(l) → Al₂Br₆(s) [unbalanced] How many moles of Al are needed to form 2.43 mol of Al₂Br₆?

Correct Answer
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The first step in the Ostwald process for producing nitric acid is as follows: 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g) . If the reaction of 15.0 g of ammonia with 15.0 g of oxygen gas yields 8.70 g of nitric oxide, what is the percent yield of this reaction?

Correct Answer
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Correct Answer
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Calculate the formula mass of ammonium arsenate, (NH₄) ₃AsO₄.

Correct Answer
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Hydrochloric acid can be prepared by the following reaction: 2NaCl(s) + H₂SO₄(aq) → 2HCl(g) + Na₂SO₄(s) What mass of HCl can be prepared from 2.00 mol H₂SO₄ and 150. g NaCl?

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What is the average mass, in grams, of one atom of iron? (N_A = 6.022 × 10²³ mol^-1)

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Correct Answer
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What is the coefficient of O₂ when the following equation is properly balanced with the smallest set of whole numbers? C₂H₄ + O₂→ CO₂ + H₂O

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Correct Answer
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Theoretical yield = ...
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Calculate the formula mass of potassium permanganate, KMnO₄.

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Sulfur trioxide can react with atmospheric water vapor to form sulfuric acid that falls as acid rain. Calculate the mass in grams of 3.65 × 10²⁰ molecules of sulfur trioxide.

Correct Answer
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Correct Answer
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When octane (C₈H₁₈) is burned in a particular internal combustion engine, the yield of products (carbon dioxide and water) is 93%. What mass of carbon dioxide will be produced in this engine when 15.0 g of octane is burned with 15.0 g of oxygen gas?

Correct Answer
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What is the theoretical yield of vanadium, in moles, that can be produced by the reaction of 2.0 mole of V₂O₅ with 6.0 mole of calcium based on the following chemical equation? V₂O₅(s) + 5Ca(l) → 2V(l) + 5CaO(s)

Correct Answer
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A certain compound of bromine and fluorine is used to make UF₆, which is an important chemical in the processing and reprocessing of nuclear fuel. The compound contains 58.37 mass percent bromine. What is its empirical formula?

Correct Answer
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Correct Answer
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Correct Answer
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What is the maximum number of grams of ammonia, NH₃, which can be obtained from the reaction of 10.0 g of H₂ and 80.0 g of N₂? N₂ + 3H₂→ 2NH₃

Correct Answer
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