Question 1

Aluminum oxide (used as an adsorbent or a catalyst for organic reactions)  forms when aluminum reacts with oxygen. 4Al(s)  + 3O2(g)  → 2Al2O3(s) 
A mixture of 82.49 g of aluminum (ℳ= 26.98 g/mol)  and 117.65 g of oxygen (ℳ = 32.00 g/mol)  is allowed to react. What mass of aluminum oxide (ℳ = 101.96 g/mol)  can be formed?

Accepted Answer

A)  155.8 g
B)  200.2 g
C)  249.9 g
D)  311.7 g
E)  374.9 gF) B) and D)
G) A) and E)

Question 2

Calculate the molar mass of Ca(BO2) 2·6H2O.

Accepted Answer

A)  273.87 g/mol
B)  233.79 g/mol
C)  183.79 g/mol
D)  174.89 g/mol
E)  143.71 g/molF) B) and E)
G) C) and D)

Question 3

How many molecules of molecular oxygen react with four molecules of NH3 to form four molecules of nitrogen monoxide and six molecules of water?

Accepted Answer

A)  2
B)  10
C)  3
D)  4
E)  5F) A) and B)
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 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) None of the above
G) A) and D)

Question 5

Terephthalic acid, used in the production of polyester fibers and films, is composed of carbon, hydrogen, and oxygen. When 0.6943 g of terephthalic acid was subjected to combustion analysis it produced 1.471 g CO2 and 0.226 g H2O. If its molar mass is between 158 and 167 g/mol, what is its molecular formula?

Accepted Answer

A)  C 4H 6O 7
B)  C 6H 8O 5
C)  C 7H 12O 4
D)  C 4H 3O 2
E)  C 8H 6O 4F) C) and D)
G) None of the above

Question 6

How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH3? 4NH3(g)  + 5O2(g)  → 4NO(g)  + 6H2O(g)

Accepted Answer

A)  469.7 g
B)  300.6 g
C)  250.0 g
D)  3.406 g
E)  2.180 gF) A) and D)
G) None of the above

Question 7

Sulfur dioxide reacts with chlorine to produce thionyl chloride (used as a drying agent for inorganic halides)  and dichlorine oxide (used as a bleach for wood, pulp, and textiles) . SO2(g)  + 2Cl2(g)  → SOCl2(g)  + Cl2O(g) 
If 0.400 mol of Cl2 reacts with excess SO2, how many moles of Cl2O are formed?

Accepted Answer

A)  0.800 mol
B)  0.400 mol
C)  0.200 mol
D)  0.100 mol
E)  0.0500 molF) A) and D)
G) A) and C)

Question 8

Magnesium (used in the manufacture of light alloys)  reacts with iron(III)  chloride to form magnesium chloride and iron. 3Mg(s)  + 2FeCl3(s)  → 3MgCl2(s)  + 2Fe(s) 
A mixture of 41.0 g of magnesium (ℳ = 24.31 g/mol)  and 175 g of iron(III)  chloride (ℳ= 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 FeCl 3 remain.
B)  Limiting reactant is Mg; 134 g of FeCl 3 remain.
C)  Limiting reactant is Mg; 104 g of FeCl 3 remain.
D)  Limiting reactant is FeCl 3; 2 g of Mg remain.
E)  Limiting reactant is FeCl 3; 87 g of Mg remain.F) C) and D)
G) A) and D)

Question 9

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)  C 4H 8O 6
B)  C 5H 10O 5
C)  C 5H 12O 5
D)  C 6H 12O 4
E)  None of these choices are correct.F) B) and C)
G) A) and E)

Question 10

What is the percent yield for the reaction PCl3(g)  + Cl2(g)  → PCl5(g) 
If 119.3 g of PCl5 (ℳ = 208.2 g/mol)  are formed when 61.3 g of Cl2 (ℳ = 70.91 g/mol)  react with excess PCl3?

Accepted Answer

A)  195%
B)  85.0%
C)  66.3%
D)  51.4%
E)  43.7%F) B) and E)
G) C) and D)

Question 11

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 are correct.F) A) and B)
G) C) and D)

Question 12

Aluminum reacts with oxygen to produce aluminum oxide which can be used as an adsorbent, desiccant, or catalyst for organic reactions. 4Al(s)  + 3O2(g)  → 2Al2O3(s) 
A mixture of 82.49 g of aluminum (ℳ = 26.98 g/mol)  and 117.65 g of oxygen (ℳ= 32.00 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)  Oxygen is the limiting reactant; 19.81 g of aluminum remain.
B)  Oxygen is the limiting reactant; 35.16 g of aluminum remain.
C)  Aluminum is the limiting reactant; 16.70 g of oxygen remain.
D)  Aluminum is the limiting reactant; 35.16 g of oxygen remain.
E)  Aluminum is the limiting reactant; 44.24 g of oxygen remain.F) B) and C)
G) A) and D)

Question 13

Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus decaoxide and water. PH3(g)  + O2(g)  → P4O10(s)  + H2O(g)  [unbalanced]
Calculate the mass of P4O10(s)  formed when 225 g of PH3 reacts with excess oxygen.

Accepted Answer

A)  1880 g
B)  940. g
C)  900. g
D)  470 g
E)  56.3 gF) A) and B)
G) D) and E)

Question 14

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)  NH 2O 5
B)  N 2H 4O 4
C)  N 3H 3O 3
D)  N 4H 8O 2
E)  N 2H 2O 4F) B) and C)
G) A) and B)

Question 15

Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH) 2.

Accepted Answer

A)  3.28 mol
B)  2.32 mol
C)  0.431 mol
D)  0.305 mol
E)  0.200 molF) B) and E)
G) A) and B)

Question 16

Aluminum will react 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) D) and E)
G) All of the above

Question 17

Aluminum sulfate, Al2(SO4) 3, is used in tanning leather, purifying water, and manufacture of antiperspirants. Calculate its molar mass.

Accepted Answer

A)  450.06 g/mol
B)  342.15 g/mol
C)  315.15 g/mol
D)  278.02 g/mol
E)  74.98 g/molF) B) and D)
G) A) and E)

Question 18

Alkanes are compounds of carbon and hydrogen with the general formula CnH2n+2. An alkane component of gasoline has a molar mass of between 125 and 130 g/mol. What is the value of n for this alkane?

Accepted Answer

A)  4
B)  9
C)  10
D)  13
E)  14F) A) and B)
G) C) and E)

Question 19

Ammonia will react with fluorine to produce dinitrogen tetrafluoride and hydrogen fluoride (used in production of aluminum, in uranium processing, and in frosting of light bulbs) . 2NH3(g)  + 5F2(g)  → N2F4(g)  + 6HF(g) 
How many moles of NH3 are needed to react completely with 13.6 mol of F2?

Accepted Answer

A)  34.0 mol
B)  27.2 mol
C)  6.80 mol
D)  5.44 mol
E)  2.27 molF) B) and C)
G) B) and D)

Question 20

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

Accepted Answer

A)  4.00 × 10 2 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 C)

Exam 3: Stoichiometry of Formulas and Equations

Correct Answer
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Calculate the molar mass of Ca(BO₂) ₂·6H₂O.

Correct Answer
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Aluminum sulfate, Al₂(SO₄) ₃, is used in tanning leather, purifying water, and manufacture of antiperspirants. Calculate its molar mass.

Correct Answer
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Correct Answer
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How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH₃? 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

Correct Answer
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Correct Answer
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Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH) ₂.

Correct Answer
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Correct Answer
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Aluminum will react 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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How many molecules of molecular oxygen react with four molecules of NH₃ to form four molecules of nitrogen monoxide and six molecules of water?

Correct Answer
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Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus decaoxide and water. PH₃(g) + O₂(g) → P₄O₁₀(s) + H₂O(g) [unbalanced] Calculate the mass of P₄O₁₀(s) formed when 225 g of PH₃reacts with excess oxygen.

Correct Answer
verified

Alkanes are compounds of carbon and hydrogen with the general formula C_nH₂n₊₂. An alkane component of gasoline has a molar mass of between 125 and 130 g/mol. What is the value of n for this alkane?

Correct Answer
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What is the percent yield for the reaction PCl₃(g) + Cl₂(g) → PCl₅(g) If 119.3 g of PCl₅ (ℳ = 208.2 g/mol) are formed when 61.3 g of Cl₂ (ℳ = 70.91 g/mol) react with excess PCl₃?

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

Correct Answer
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Determine the percent composition of potassium dichromate, K₂Cr₂O₇.

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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Correct Answer
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Exam 3: Stoichiometry of Formulas and Equations

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Calculate the molar mass of Ca(BO2) 2·6H2O.

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Aluminum sulfate, Al2(SO4) 3, is used in tanning leather, purifying water, and manufacture of antiperspirants. Calculate its molar mass.

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Correct AnswerverifiedShow Answer

How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH3? 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)

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Ammonia will react with fluorine to produce dinitrogen tetrafluoride and hydrogen fluoride (used in production of aluminum, in uranium processing, and in frosting of light bulbs) . 2NH3(g) + 5F2(g) → N2F4(g) + 6HF(g) How many moles of NH3 are needed to react completely with 13.6 mol of F2?

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Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH) 2.

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Aluminum will react 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?

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How many molecules of molecular oxygen react with four molecules of NH3 to form four molecules of nitrogen monoxide and six molecules of water?

Correct AnswerverifiedShow Answer

Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus decaoxide and water. PH3(g) + O2(g) → P4O10(s) + H2O(g) [unbalanced] Calculate the mass of P4O10(s) formed when 225 g of PH3 reacts with excess oxygen.

Correct AnswerverifiedShow Answer

Alkanes are compounds of carbon and hydrogen with the general formula CnH2n+2. An alkane component of gasoline has a molar mass of between 125 and 130 g/mol. What is the value of n for this alkane?

Correct AnswerverifiedShow Answer

What is the percent yield for the reaction PCl3(g) + Cl2(g) → PCl5(g) If 119.3 g of PCl5 (ℳ = 208.2 g/mol) are formed when 61.3 g of Cl2 (ℳ = 70.91 g/mol) react with excess PCl3?

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.

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

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Determine the percent composition of potassium dichromate, K2Cr2O7.

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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 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

Correct AnswerverifiedShow Answer

Correct Answer
verified

Calculate the molar mass of Ca(BO₂) ₂·6H₂O.

Correct Answer
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Aluminum sulfate, Al₂(SO₄) ₃, is used in tanning leather, purifying water, and manufacture of antiperspirants. Calculate its molar mass.

Correct Answer
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Correct Answer
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How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH₃? 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

Correct Answer
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Correct Answer
verified

Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH) ₂.

Correct Answer
verified

Correct Answer
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Aluminum will react 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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How many molecules of molecular oxygen react with four molecules of NH₃ to form four molecules of nitrogen monoxide and six molecules of water?

Correct Answer
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Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus decaoxide and water. PH₃(g) + O₂(g) → P₄O₁₀(s) + H₂O(g) [unbalanced] Calculate the mass of P₄O₁₀(s) formed when 225 g of PH₃reacts with excess oxygen.

Correct Answer
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Alkanes are compounds of carbon and hydrogen with the general formula C_nH₂n₊₂. An alkane component of gasoline has a molar mass of between 125 and 130 g/mol. What is the value of n for this alkane?

Correct Answer
verified

What is the percent yield for the reaction PCl₃(g) + Cl₂(g) → PCl₅(g) If 119.3 g of PCl₅ (ℳ = 208.2 g/mol) are formed when 61.3 g of Cl₂ (ℳ = 70.91 g/mol) react with excess PCl₃?

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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Determine the percent composition of potassium dichromate, K₂Cr₂O₇.

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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