Question 1

What is the coefficient of O2 when the following equation is properly balanced with the smallest set of whole numbers? ___ CH3OH + ___ O2 → ___ CO2 + ___ H2O

Accepted Answer

A)  1
B)  2
C)  3
D)  7
E)  None of these answers is correct.

Question 2

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 molecules

Question 3

What is the empirical formula for a sample containing 81.70% carbon and 18.29% hydrogen?

Accepted Answer

A)  CH
B)  CH3
C)  C2H6
D)  CH4
E)  C3H8

Question 4

A compound containing chromium and silicon contains 73.52 mass percent chromium.Determine its empirical formula.

Accepted Answer

A)  CrSi3
B)  Cr2Si3
C)  Cr3Si
D)  Cr3Si2
E)  Cr4Si3

Question 5

Balance the following equation: UO2(s) + HF(l) → UF4(s) + H2O(l)

Accepted Answer

A)  UO2(s) + 2HF(l) → UF4(s) + H2O(l) 
B)  UO2(s) + 4HF(l) → UF4(s) + 2H2O(l) 
C)  UO2(s) + H4F4(l) → UF4(s) + H4O2(l) 
D)  UO2(s) + 4HF(l) → UF4(s) + 4H2O(l) 
E)  UO2(s) + 8HF(l) → 2UF4(s) + 4H2O(l)

Question 6

Methanol (CH3OH) is converted to bromomethane (CH3Br) as follows: CH3OH + 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)  12.9%
B)  33.8%
C)  40.9%
D)  59.1%
E)  82.6%

Question 7

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)

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 g

Question 9

Hydroxyl ammonium 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)  N2H2O4

Question 10

The ______________ is defined by the following equation

Accepted Answer

The answer of The ______________ is defined by the following...

Question 11

Tetraphosphorus hexaoxide is formed by the reaction of phosphorus with oxygen gas.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)  89.4%
E)  16.3%

Question 12

How many moles of ammonia,NH3,are in 13.81 g of NH3?

Accepted Answer

A)  1.234 moles
B)  0.8107 moles
C)  8.316 × 1024 moles
D)  4.881 × 1023 moles
E)  235.3 moles

Question 13

There is only one distinct empirical formula for each compound that exists.

Accepted Answer

A) True 
 B)False

Question 14

What is the coefficient of H2O when the following equation is properly balanced with the smallest set of whole numbers? ___ Na + ___ H2O → ___ NaOH + ___ H2

Accepted Answer

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

Question 15

What mass of Cr can be produced by the reaction of 44.1 g of Cr2O3 with 35.0 g of Al according to the following chemical equation? 2Al + Cr2O3 → Al2O3 + 2Cr

Accepted Answer

A)  15.1 g
B)  30.2 g
C)  67.4 g
D)  99.9 g
E)  104 g

Question 16

If 13.9 g of oxygen react with 33.7 g of calcium to produce calcium oxide,what is the limiting reactant and what mass of calcium oxide is produced?

Accepted Answer

A)  Calcium is the limiting reactant and 47.2 g of calcium oxide are produced
B)  Oxygen is the limiting reactant and 24.4 g of calcium oxide are produced
C)  Calcium is the limiting reactant and 47.20 g of calcium oxide are produced
D)  Oxygen is the limiting reactant and 48.7 g of calcium oxide are produced
E)  Calcium is the limiting reactant and 23.6 g of calcium oxide are produced

Question 17

What mass of sodium fluoride (used in water fluoridation and the manufacture of insecticides) is required to form 485 g of sulfur tetrafluoride? 3SCl2(l) + 4NaF(s) → SF4(g) + S2Cl2(l) + 4NaCl(s)

Accepted Answer

A)  1.94 kg
B)  1.51 kg
C)  754 g
D)  205 g
E)  51.3 g

Question 18

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%

Question 19

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)  51.4%

Question 20

Calculate the molecular mass of tetraphosphorus decaoxide,P4O10,a corrosive substance which can be used as a drying agent.

Accepted Answer

A)  469.73 amu
B)  283.88 amu
C)  190.97 amu
D)  139.88 amu
E)  94.97 amu

Exam 3: Stoichiometry Ratios of Combination

The ______________ is defined by the following equation

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Methanol (CH3OH) is converted to bromomethane (CH3Br) as follows: CH3OH + 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?

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

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Calculate the molecular mass of tetraphosphorus decaoxide,P4O10,a corrosive substance which can be used as a drying agent.

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What mass of sodium fluoride (used in water fluoridation and the manufacture of insecticides) is required to form 485 g of sulfur tetrafluoride? 3SCl2(l) + 4NaF(s) → SF4(g) + S2Cl2(l) + 4NaCl(s)

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What is the coefficient of H2O when the following equation is properly balanced with the smallest set of whole numbers? ___ Na + ___ H2O → ___ NaOH + ___ H2

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What is the coefficient of O2 when the following equation is properly balanced with the smallest set of whole numbers? ___ CH3OH + ___ O2 → ___ CO2 + ___ H2O

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What mass of Cr can be produced by the reaction of 44.1 g of Cr2O3 with 35.0 g of Al according to the following chemical equation? 2Al + Cr2O3 → Al2O3 + 2Cr

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A compound containing chromium and silicon contains 73.52 mass percent chromium.Determine its empirical formula.

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Tetraphosphorus hexaoxide is formed by the reaction of phosphorus with oxygen gas.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?

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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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Balance the following equation: UO2(s) + HF(l) → UF4(s) + H2O(l)

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If 13.9 g of oxygen react with 33.7 g of calcium to produce calcium oxide,what is the limiting reactant and what mass of calcium oxide is produced?

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

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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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How many moles of ammonia,NH3,are in 13.81 g of NH3?

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Hydroxyl ammonium 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?

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There is only one distinct empirical formula for each compound that exists.

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What is the empirical formula for a sample containing 81.70% carbon and 18.29% hydrogen?

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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)

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Methanol (CH₃OH) is converted to bromomethane (CH₃Br) as follows: CH₃OH + 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?

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

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Calculate the molecular mass of tetraphosphorus decaoxide,P₄O₁₀,a corrosive substance which can be used as a drying agent.

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What mass of sodium fluoride (used in water fluoridation and the manufacture of insecticides) is required to form 485 g of sulfur tetrafluoride? 3SCl₂(l) + 4NaF(s) → SF₄(g) + S₂Cl₂(l) + 4NaCl(s)

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What is the coefficient of H2O when the following equation is properly balanced with the smallest set of whole numbers? _ Na + _ H₂O → _ NaOH + _ H₂

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What is the coefficient of O2 when the following equation is properly balanced with the smallest set of whole numbers? _ CH₃OH + _ O₂ → _ CO₂ + _ H₂O

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What mass of Cr can be produced by the reaction of 44.1 g of Cr₂O₃ with 35.0 g of Al according to the following chemical equation? 2Al + Cr₂O₃ → Al₂O₃ + 2Cr

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Correct Answer
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Tetraphosphorus hexaoxide is formed by the reaction of phosphorus with oxygen gas.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?

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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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Balance the following equation: UO₂(s) + HF(l) → UF₄(s) + H₂O(l)

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

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How many moles of ammonia,NH₃,are in 13.81 g of NH₃?

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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)

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