Question 1

The iodine "clock reaction" involves the following sequence of reactions occurring in a reaction mixture in a single beaker.
1)  IO3-(aq)  + 5I-(aq)  + 6H+(aq)   3I2(aq)  + 3H2O(l) 
2)  I2(aq)  + 2S2O32-(aq)   2I-(aq)  + S4O62-(aq) 
The molecular iodine (I2)  formed in reaction 1 is immediately used up in reaction 2, so that no iodine accumulates. What is the overall reaction occurring in this experiment?

Accepted Answer

A)  IO3-(aq)  + 3I-(aq)  + 2S2O32-(aq)  + 6H+(aq)   2I2(aq)  + S4O62-(aq)  + 3H2O(l) 
B)  IO3-(aq)  + 4S2O32-(aq)  + 6H+(aq)   I-(aq)  + 2S4O62-(aq)  + 3H2O(l) 
C)  IO3-(aq)  + 6S2O32-(aq)  + 6H+(aq)   I-(aq)  + 3S4O62-(aq)  + 3H2O(l) 
D)  IO3-(aq)  + I2(aq)  + 8S2O32-(aq)  + 6H+(aq)   3I-(aq)  + 4S4O62-(aq)  + 3H2O(l) 
E)  IO3-(aq)  + 2I2(aq)  + 6S2O32-(aq)  + 6H+(aq)   5I-(aq)  + 3S4O62-(aq)  + 3H2O(l) F) B) and D)
G) B) and E)

Question 2

Copper(II)  sulfate pentahydrate, CuSO4·5H2O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO4·5H2O.

Accepted Answer

A)   249.7 g
B)   144.0 g
C)   96.00 g
D)   80.00 g
E)   64.00 gF) A) and B)
G) None of the above

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 C)
G) A) and E)

Question 4

Which of the following samples contains the greatest total number atoms?

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 D)
G) D) and E)

Question 5

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) A) and E)
G) A) and B)

Question 6

Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na2SO4.

Accepted Answer

A)   1.244 × 1023 O atoms
B)   4.976 × 1023 O atoms
C)   2.409 × 1024 O atoms
D)   2.915 × 1024 O atoms
E)   1.166 × 1025 O atomsF) A) and C)
G) B) and D)

Question 7

A compound consisting of C, H, and O only, has a molar mass of 331.5 g/mol. Combustion of 0.1000 g of this compound caused a 0.2921 g increase in the mass of the CO2 absorber and a 0.0951 g increase in the mass of the H2O absorber. What is the empirical formula of the compound?

Accepted Answer

C₂₂H₃₅O₂

Question 8

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 C)
G) C) and D)

Question 9

In a blast furnace, elemental iron is produced from a mixture of coke (C) , iron ore (Fe3O4) , and other reactants. An important reaction sequence is 
2C(s)  + O2(g)   2CO(g) 
Fe3O4(s)  + 4CO(g)   3Fe(l)  + 4CO2(g) 
How many moles of iron can be formed in this sequence when 1.00 mol of carbon, as coke, is consumed?

Accepted Answer

A)   6.00 mol Fe
B)   3.00 mol Fe
C)   1.33 mol Fe
D)   1.25 mol Fe
E)   0.750 mol FeF) A) and C)
G) A) and D)

Question 10

How many protons are there in a molecule of adrenaline (C9H13NO3) , a neurotransmitter and hormone?

Accepted Answer

A)   22
B)   26
C)   43
D)   98
E)   183F) C) and E)
G) C) and D) D

Question 11

Balance the following equation: 
C8H18O3(l)  + O2(g)   H2O(g)  + CO2(g)

Accepted Answer

A)   C8H18O3(l)  + 8O2(g)   9H2O(g)  + 8CO2(g) 
B)   C8H18O3(l)  + 11O2(g)   9H2O(g)  + 8CO2(g) 
C)   2C8H18O3(l)  + 22O2(g)   9H2O(g)  + 16CO2(g) 
D)   C8H18O3(l)  + 13O2(g)   18H2O(g)  + 8CO2(g) 
E)   2C8H18O3(l)  + 17O2(g)   18H2O(g)  + 16CO2(g) F) A) and E)
G) A) and B)

Question 12

Potassium chloride is used as a substitute for sodium chloride for individuals with high blood pressure. Identify the limiting reactant and determine the mass of the excess reactant remaining when 7.00 g of chlorine gas reacts with 5.00 g of potassium to form potassium chloride.

Accepted Answer

A)   Potassium is the limiting reactant; 2.47 g of chlorine remain.
B)   Potassium is the limiting reactant; 7.23 g of chlorine remain.
C)   Chlorine is the limiting reactant; 4.64 g of potassium remain.
D)   Chlorine is the limiting reactant; 2.70 g of potassium remain.
E)   No limiting reagent: the reactants are present in the correct stoichiometric ratio.F) A) and B)
G) A) and C)

Question 13

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) None of the above
G) All of the above E

Question 14

Methanol (CH4O)  is converted to bromomethane (CH3Br)  as follows:
 CH4O + HBr  CH3Br + H2O
If 12.23 g of bromomethane are produced when 5.00 g of methanol is reacted with excess HBr, what is the percentage yield?

Accepted Answer

A)   40.9%
B)   82.6%
C)   100.%
D)   121%
E)   245%F) B) and E)
G) B) and C)

Question 15

In a correctly balanced equation, the number of reactant molecules must equal the number of product molecules.

Accepted Answer

A) True 
 B)False

Question 16

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 D)
G) None of the above

Question 17

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 the aboveF) C) and D)
G) B) and E)

Question 18

Sodium bromate is used in a mixture which dissolves gold from its ores. Calculate the mass in grams of 4.68 mol of sodium bromate.

Accepted Answer

A)   706 g
B)   482 g
C)   383 g
D)   32.2 g
E)   0.0310 gF) D) and E)
G) A) and E)

Question 19

A single atom of hydrogen has a mass of 1.0 amu, while a mole of hydrogen atoms has a mass of 1.0 g. Select the correct conversion factor between atomic mass units and grams.

Accepted Answer

A)   1 amu = 1 g exactly
B)   1 amu = 6.0 × 1023 g
C)   1 g = 6.0 × 1023 amu
D)   1 g = 1.7 × 10-24 amu
E)   none of the aboveF) B) and D)
G) None of the above

Question 20

Calculate the molar mass of (NH4) 3AsO4.

Accepted Answer

A)   417.80 g/mol
B)   193.03 g/mol
C)   165.02 g/mol
D)   156.96 g/mol
E)   108.96 g/molF) D) and E)
G) None of the above

Exam 3: Stoichiometry of Formulas and Equations

Correct Answer
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Copper(II) sulfate pentahydrate, CuSO₄·5H₂O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO₄·5H₂O.

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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Which of the following samples contains the greatest total number atoms?

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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Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na₂SO₄.

Correct Answer
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A compound consisting of C, H, and O only, has a molar mass of 331.5 g/mol. Combustion of 0.1000 g of this compound caused a 0.2921 g increase in the mass of the CO₂ absorber and a 0.0951 g increase in the mass of the H₂O absorber. What is the empirical formula of the compound?

Correct Answer
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C₂₂H₃₅O₂

Correct Answer
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Correct Answer
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How many protons are there in a molecule of adrenaline (C₉H₁₃NO₃) , a neurotransmitter and hormone?

Correct Answer
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D

Balance the following equation: C₈H₁₈O₃(l) + O₂(g)  H₂O(g) + CO₂(g)

Correct Answer
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Potassium chloride is used as a substitute for sodium chloride for individuals with high blood pressure. Identify the limiting reactant and determine the mass of the excess reactant remaining when 7.00 g of chlorine gas reacts with 5.00 g of potassium to form potassium chloride.

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

Correct Answer
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E

Methanol (CH₄O) is converted to bromomethane (CH₃Br) as follows: CH₄O + HBr  CH₃Br + H₂O If 12.23 g of bromomethane are produced when 5.00 g of methanol is reacted with excess HBr, what is the percentage yield?

Correct Answer
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In a correctly balanced equation, the number of reactant molecules must equal the number of product molecules.

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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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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Sodium bromate is used in a mixture which dissolves gold from its ores. Calculate the mass in grams of 4.68 mol of sodium bromate.

Correct Answer
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A single atom of hydrogen has a mass of 1.0 amu, while a mole of hydrogen atoms has a mass of 1.0 g. Select the correct conversion factor between atomic mass units and grams.

Correct Answer
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Calculate the molar mass of (NH₄) ₃AsO₄.

Correct Answer
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Exam 3: Stoichiometry of Formulas and Equations

Correct AnswerverifiedShow Answer

Copper(II) sulfate pentahydrate, CuSO4·5H2O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO4·5H2O.

Correct AnswerverifiedShow Answer

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

Which of the following samples contains the greatest total number atoms?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na2SO4.

Correct AnswerverifiedShow Answer

A compound consisting of C, H, and O only, has a molar mass of 331.5 g/mol. Combustion of 0.1000 g of this compound caused a 0.2921 g increase in the mass of the CO2 absorber and a 0.0951 g increase in the mass of the H2O absorber. What is the empirical formula of the compound?

Correct AnswerverifiedC22H35O2

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

How many protons are there in a molecule of adrenaline (C9H13NO3) , a neurotransmitter and hormone?

Correct AnswerverifiedD

Balance the following equation: C8H18O3(l) + O2(g)  H2O(g) + CO2(g)

Correct AnswerverifiedShow Answer

Potassium chloride is used as a substitute for sodium chloride for individuals with high blood pressure. Identify the limiting reactant and determine the mass of the excess reactant remaining when 7.00 g of chlorine gas reacts with 5.00 g of potassium to form potassium chloride.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedE

Methanol (CH4O) is converted to bromomethane (CH3Br) as follows: CH4O + HBr  CH3Br + H2O If 12.23 g of bromomethane are produced when 5.00 g of methanol is reacted with excess HBr, what is the percentage yield?

Correct AnswerverifiedShow Answer

In a correctly balanced equation, the number of reactant molecules must equal the number of product molecules.

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

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

Sodium bromate is used in a mixture which dissolves gold from its ores. Calculate the mass in grams of 4.68 mol of sodium bromate.

Correct AnswerverifiedShow Answer

A single atom of hydrogen has a mass of 1.0 amu, while a mole of hydrogen atoms has a mass of 1.0 g. Select the correct conversion factor between atomic mass units and grams.

Correct AnswerverifiedShow Answer

Calculate the molar mass of (NH4) 3AsO4.

Correct AnswerverifiedShow Answer

Correct Answer
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Copper(II) sulfate pentahydrate, CuSO₄·5H₂O, is used as a fungicide and algicide. Calculate the mass of oxygen in 1.000 mol of CuSO₄·5H₂O.

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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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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Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na₂SO₄.

Correct Answer
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A compound consisting of C, H, and O only, has a molar mass of 331.5 g/mol. Combustion of 0.1000 g of this compound caused a 0.2921 g increase in the mass of the CO₂ absorber and a 0.0951 g increase in the mass of the H₂O absorber. What is the empirical formula of the compound?

Correct Answer
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C₂₂H₃₅O₂

Correct Answer
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Correct Answer
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How many protons are there in a molecule of adrenaline (C₉H₁₃NO₃) , a neurotransmitter and hormone?

Correct Answer
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D

Balance the following equation: C₈H₁₈O₃(l) + O₂(g)  H₂O(g) + CO₂(g)

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

Correct Answer
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E

Methanol (CH₄O) is converted to bromomethane (CH₃Br) as follows: CH₄O + HBr  CH₃Br + H₂O If 12.23 g of bromomethane are produced when 5.00 g of methanol is reacted with excess HBr, what is the percentage yield?

Correct Answer
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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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Correct Answer
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Correct Answer
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Correct Answer
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Calculate the molar mass of (NH₄) ₃AsO₄.

Correct Answer
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