Question 1

Tetraphosphorus hexaoxide (? = 219.9 g/mol)  is formed by the reaction of phosphorus with oxygen gas. 
P4(s)  + 3O2(g)   →\rightarrow→  P4O6(s) 
If a mixture of 75.3 g of phosphorus and 38.7 g of oxygen produce 43.3 g of P4O6, what is the percent yield for the reaction?

Accepted Answer

A)   57.5%
B)   48.8%
C)   38.0%
D)   32.4%
E)   16.3% F) B) and D)
G) A) and B) B

Question 2

Lead(II)  sulfide was once used in glazing earthenware. It will also react with hydrogen peroxide to form lead(II)  sulfate and water. How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(II)  sulfide?

Accepted Answer

A)   151 g
B)   123 g
C)   50.3 g
D)   37.7 g
E)   9.41 gF) C) and D)
G) C) and E) A

Question 3

Determine the percent composition of potassium dichromate, K2Cr2O7.

Accepted Answer

A)   17.5% K, 46.6% Cr, 35.9% O
B)   29.8% K, 39.7% Cr, 30.5% O
C)   36.5% K, 48.6% Cr, 14.9% O
D)   37.2% K, 24.7% Cr, 38.1% O
E)   None of these choices is correct.F) A) and D)
G) None of the above

Question 4

One mole of O2 has a mass of 16.0 g.

Accepted Answer

A) True 
 B)False

Question 5

Phosphorus pentachloride, PCl5, a white solid that has a pungent, unpleasant odor, is used as a catalyst for certain organic reactions. Calculate the number of moles in 38.7 g of PCl5.

Accepted Answer

A)   5.38 mol
B)   3.55 mol
C)   0.583 mol
D)   0.282 mol
E)   0.186 molF) B) and C)
G) D) and E)

Question 6

What is the mass in grams of 0.250 mol of the common antacid calcium carbonate?

Accepted Answer

A)   4.00 * 102 g
B)   25.0 g
C)   17.0 g
D)   4.00 * 10¯2 g
E)   2.50 *10¯3 gF) C) and D)
G) A) and E)

Question 7

Household sugar, sucrose, has the molecular formula C12H22O11. What is the % of carbon in sucrose, by mass?

Accepted Answer

A)   26.7%
B)   33.3%
C)   41.4%
D)   42.1%
E)   52.8%F) B) and E)
G) A) and B)

Question 8

Aqueous potassium iodate (KIO3)  and potassium iodide (KI)  react in the presence of dilute hydrochloric acid, as shown below. 
KIO3(aq)  + 5KI(aq)  + 6HCl(aq)   →\rightarrow→  3I2(aq)  + 6KCl(aq)  + 3H2O(l) 
What mass of iodine (I2)  is formed when 50.0 mL of 0.020 M KIO3 solution reacts with an excess of KI and HCl?

Accepted Answer

A)   0.13 g I2
B)   0.25 g I2
C)   0.38 g I2
D)   0.76 g I2
E)   None of these answers is correct. F) A) and B)
G) B) and E)

Question 9

Calcium chloride is used to melt ice and snow on roads and sidewalks and to remove water from organic liquids. Calculate the molarity of a solution prepared by diluting 165 mL of 0.688 M calcium chloride to 925.0 mL.

Accepted Answer

A)   3.86 M
B)   0.743 M
C)   0.222 M
D)   0.123 M
E)   0.114 MF) C) and E)
G) D) and E)

Question 10

In the combustion analysis of 0.1127 g of glucose (C6H12O6) , what mass, in grams, of CO2 would be produced?

Accepted Answer

A)   0.0451 g
B)   0.0825 g
C)   0.1652 g
D)   0.4132 g
E)   1.466 gF) B) and E)
G) All of the above

Question 11

Which of the following samples has the most moles of the compound?

Accepted Answer

A)   50.0 g of Li2O
B)   75.0 g of CaO
C)   200.0 g of Fe2O3
D)   50.0 g of CO2
E)   100.0 g of SO3F) A) and B)
G) A) and C)

Question 12

Magnesium (used in the manufacture of light alloys)  reacts with iron(III)  chloride to form magnesium chloride and iron. 
3Mg(s)  + 2FeCl3(s)   →\rightarrow→  3MgCl2(s)  + 2Fe(s) 
A mixture of 41.0 g of magnesium (? = 24.31 g/mol)  and 175 g of iron(III)  chloride (? = 162.2 g/mol)  is allowed to react. Identify the limiting reactant and determine the mass of the excess reactant present in the vessel when the reaction is complete.

Accepted Answer

A)   Limiting reactant is Mg; 67 g of FeCl3 remain.
B)   Limiting reactant is Mg; 134 g of FeCl3 remain.
C)   Limiting reactant is Mg; 104 g of FeCl3 remain.
D)   Limiting reactant is FeCl3; 2 g of Mg remain.
E)   Limiting reactant is FeCl3; 87 g of Mg remain. F) C) and D)
G) A) and D)

Question 13

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 SO3.

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) C) and E)
G) None of the above

Question 14

Analysis of a carbohydrate showed that it consisted of 40.0 % C, 6.71 % H and 53.3 % O by mass. Its molecular mass was found to be between 140 and 160 amu. What is the molecular formula of this compound?

Accepted Answer

A)   C4H8O6
B)   C5H10O5
C)   C5H12O5
D)   C6H12O4
E)   None of these choices is correct.F) B) and E)
G) All of the above

Question 15

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass O. If its molar mass is between 94 and 98 g/mol, what is its molecular formula?

Accepted Answer

A)   NH2O5
B)   N2H4O4
C)   N3H3O3
D)   N4H8O2
E)   N2H2O4F) A) and B)
G) None of the above

Question 16

Lead (II)  nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO3) 2.

Accepted Answer

A)   107 g
B)   90.8 g
C)   87.0 g
D)   83.4 g
E)   62.6 gF) All of the above
G) B) and C) C

Question 17

When a solution is diluted with water, the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Accepted Answer

A) True 
 B)False

Question 18

Calculate the mass in grams of 8.35 * 1022 molecules of CBr4.

Accepted Answer

A)   0.0217 g
B)   0.139 g
C)   7.21 g
D)   12.7 g
E)   46.0 gF) B) and E)
G) C) and D)

Question 19

How many atoms are in a drop of mercury that has a diameter of 1.0 mm? (Volume of a sphere is 4  π\piπ r3/3; density of mercury = 13.6 g/cm3)

Accepted Answer

A)   2.1 * 1019
B)   1.7 *1020
C)   2.1 *1022
D)   1.7 * 1023
E)   None of these choices is correct. F) None of the above
G) B) and E)

Question 20

Calcium fluoride, CaF2, is a source of fluorine and is used to fluoridate drinking water. Calculate its molar mass.

Accepted Answer

A)   118.15 g/mol
B)   99.15 g/mol
C)   78.07 g/mol
D)   59.08 g/mol
E)   50.01 g/molF) B) and D)
G) A) and E)

Exam 3: Stoichiometry of Formulas and Equations

Tetraphosphorus hexaoxide (? = 219.9 g/mol) is formed by the reaction of phosphorus with oxygen gas. P₄(s) + 3O₂(g) $\rightarrow$ P₄O₆(s) If a mixture of 75.3 g of phosphorus and 38.7 g of oxygen produce 43.3 g of P₄O₆, what is the percent yield for the reaction?

Correct Answer
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B

Lead(II) sulfide was once used in glazing earthenware. It will also react with hydrogen peroxide to form lead(II) sulfate and water. How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(II) sulfide?

Correct Answer
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A

Determine the percent composition of potassium dichromate, K₂Cr₂O₇.

Correct Answer
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One mole of O₂ has a mass of 16.0 g.

Correct Answer
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Phosphorus pentachloride, PCl₅, a white solid that has a pungent, unpleasant odor, is used as a catalyst for certain organic reactions. Calculate the number of moles in 38.7 g of PCl₅.

Correct Answer
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What is the mass in grams of 0.250 mol of the common antacid calcium carbonate?

Correct Answer
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Household sugar, sucrose, has the molecular formula C₁₂H₂₂O₁₁. What is the % of carbon in sucrose, by mass?

Correct Answer
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Correct Answer
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Calcium chloride is used to melt ice and snow on roads and sidewalks and to remove water from organic liquids. Calculate the molarity of a solution prepared by diluting 165 mL of 0.688 M calcium chloride to 925.0 mL.

Correct Answer
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In the combustion analysis of 0.1127 g of glucose (C₆H₁₂O₆) , what mass, in grams, of CO₂ would be produced?

Correct Answer
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Which of the following samples has the most moles of the compound?

Correct Answer
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Correct Answer
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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 SO₃.

Correct Answer
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Analysis of a carbohydrate showed that it consisted of 40.0 % C, 6.71 % H and 53.3 % O by mass. Its molecular mass was found to be between 140 and 160 amu. What is the molecular formula of this compound?

Correct Answer
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Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass O. If its molar mass is between 94 and 98 g/mol, what is its molecular formula?

Correct Answer
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Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO₃) ₂.

Correct Answer
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C

When a solution is diluted with water, the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Correct Answer
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Calculate the mass in grams of 8.35 * 10²² molecules of CBr₄.

Correct Answer
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How many atoms are in a drop of mercury that has a diameter of 1.0 mm? (Volume of a sphere is 4 $\pi$ r³/3; density of mercury = 13.6 g/cm³)

Correct Answer
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Calcium fluoride, CaF₂, is a source of fluorine and is used to fluoridate drinking water. Calculate its molar mass.

Correct Answer
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Exam 3: Stoichiometry of Formulas and Equations

Tetraphosphorus hexaoxide (? = 219.9 g/mol) is formed by the reaction of phosphorus with oxygen gas. P4(s) + 3O2(g) →\rightarrow→ P4O6(s) If a mixture of 75.3 g of phosphorus and 38.7 g of oxygen produce 43.3 g of P4O6, what is the percent yield for the reaction?

Correct AnswerverifiedB

Lead(II) sulfide was once used in glazing earthenware. It will also react with hydrogen peroxide to form lead(II) sulfate and water. How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(II) sulfide?

Correct AnswerverifiedA

Determine the percent composition of potassium dichromate, K2Cr2O7.

Correct AnswerverifiedShow Answer

One mole of O2 has a mass of 16.0 g.

Correct AnswerverifiedShow Answer

Phosphorus pentachloride, PCl5, a white solid that has a pungent, unpleasant odor, is used as a catalyst for certain organic reactions. Calculate the number of moles in 38.7 g of PCl5.

Correct AnswerverifiedShow Answer

What is the mass in grams of 0.250 mol of the common antacid calcium carbonate?

Correct AnswerverifiedShow Answer

Household sugar, sucrose, has the molecular formula C12H22O11. What is the % of carbon in sucrose, by mass?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Calcium chloride is used to melt ice and snow on roads and sidewalks and to remove water from organic liquids. Calculate the molarity of a solution prepared by diluting 165 mL of 0.688 M calcium chloride to 925.0 mL.

Correct AnswerverifiedShow Answer

In the combustion analysis of 0.1127 g of glucose (C6H12O6) , what mass, in grams, of CO2 would be produced?

Correct AnswerverifiedShow Answer

Which of the following samples has the most moles of the compound?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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 SO3.

Correct AnswerverifiedShow Answer

Analysis of a carbohydrate showed that it consisted of 40.0 % C, 6.71 % H and 53.3 % O by mass. Its molecular mass was found to be between 140 and 160 amu. What is the molecular formula of this compound?

Correct AnswerverifiedShow Answer

Hydroxylamine nitrate contains 29.17 mass % N, 4.20 mass % H, and 66.63 mass O. If its molar mass is between 94 and 98 g/mol, what is its molecular formula?

Correct AnswerverifiedShow Answer

Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO3) 2.

Correct AnswerverifiedC

When a solution is diluted with water, the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Correct AnswerverifiedShow Answer

Calculate the mass in grams of 8.35 * 1022 molecules of CBr4.

Correct AnswerverifiedShow Answer

How many atoms are in a drop of mercury that has a diameter of 1.0 mm? (Volume of a sphere is 4 π\piπ r3/3; density of mercury = 13.6 g/cm3)

Correct AnswerverifiedShow Answer

Calcium fluoride, CaF2, is a source of fluorine and is used to fluoridate drinking water. Calculate its molar mass.

Correct AnswerverifiedShow Answer

Tetraphosphorus hexaoxide (? = 219.9 g/mol) is formed by the reaction of phosphorus with oxygen gas. P₄(s) + 3O₂(g) $\rightarrow$ P₄O₆(s) If a mixture of 75.3 g of phosphorus and 38.7 g of oxygen produce 43.3 g of P₄O₆, what is the percent yield for the reaction?

Correct Answer
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B

Correct Answer
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A

Determine the percent composition of potassium dichromate, K₂Cr₂O₇.

Correct Answer
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One mole of O₂ has a mass of 16.0 g.

Correct Answer
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Phosphorus pentachloride, PCl₅, a white solid that has a pungent, unpleasant odor, is used as a catalyst for certain organic reactions. Calculate the number of moles in 38.7 g of PCl₅.

Correct Answer
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Correct Answer
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Household sugar, sucrose, has the molecular formula C₁₂H₂₂O₁₁. What is the % of carbon in sucrose, by mass?

Correct Answer
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Correct Answer
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Correct Answer
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In the combustion analysis of 0.1127 g of glucose (C₆H₁₂O₆) , what mass, in grams, of CO₂ would be produced?

Correct Answer
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Correct Answer
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Correct Answer
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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 SO₃.

Correct Answer
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Correct Answer
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Correct Answer
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Lead (II) nitrate is a poisonous substance which has been used in the manufacture of special explosives and as a sensitizer in photography. Calculate the mass of lead in 139 g of Pb(NO₃) ₂.

Correct Answer
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C

Correct Answer
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Calculate the mass in grams of 8.35 * 10²² molecules of CBr₄.

Correct Answer
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How many atoms are in a drop of mercury that has a diameter of 1.0 mm? (Volume of a sphere is 4 $\pi$ r³/3; density of mercury = 13.6 g/cm³)

Correct Answer
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Calcium fluoride, CaF₂, is a source of fluorine and is used to fluoridate drinking water. Calculate its molar mass.

Correct Answer
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