Question 1

Which statement, A-D, regarding the carbon cycle is not correct?

Accepted Answer

A)  Petroleum, coal, and other carbon sediments are produced. 
B)  Respiration produces atmospheric carbon dioxide. 
C)  Water is a reactant in photosynthesis. 
D)  Forest fires are part of the carbon cycle. 
E)  A-D are all correct. 
A)  Petroleum, coal, and other carbon sediments are produced. 
B)  Respiration produces atmospheric carbon dioxide. 
C)  Water is a reactant in photosynthesis. 
D)  Forest fires are part of the carbon cycle. 
E)  A-D are all correct.

Question 2

Glucose (C6H12O6) is oxidized by molecular oxygen to carbon dioxide and water. How many O2 molecules are needed for each molecule of glucose that is oxidized?

Accepted Answer

A)  1 
B)  2 
C)  6 
D)  12 
E)  18 
A)  1 
B)  2 
C)  6 
D)  12 
E)  18

Question 3

The mass of 0.25 mol of some element is 8.0 g. What is the element?

Accepted Answer

A)  O2 
B)  N2 
C)  Cl2 
D)  Br2 
E)  H2 
A)  O2 
B)  N2 
C)  Cl2 
D)  Br2 
E)  H2

Question 4

How many mL of C16H34 are needed to react with 0.050 mol O2, assuming complete combustion occurs? The density of C16H34 is 0.80 g/mL.

Accepted Answer

A)  0.99 mL 
B)  0.37 mL 
C)  0.58 mL 
D)  0.46 mL 
E)  0.89 mL 
A)  0.99 mL 
B)  0.37 mL 
C)  0.58 mL 
D)  0.46 mL 
E)  0.89 mL

Question 5

How many oxygen atoms are there in 27.0 g of sodium sulfate (Na2SO4)?

Accepted Answer

A)  1.15 * 1023 atoms 
B)  4.58 *1023 atoms 
C)  5.73 * 1023 atoms 
D)  2.41 * 1024 atoms 
E)  6.88 * 1023 atoms 
A)  1.15 * 1023 atoms 
B)  4.58 *1023 atoms 
C)  5.73 * 1023 atoms 
D)  2.41 * 1024 atoms 
E)  6.88 * 1023 atoms

Question 6

Chemical analysis of an organic compound found the following composition: 40.0% C, 53.5% O, and 6.7% H. If the molar mass is 180.2 g/mol, how many empirical formula units are there in the molecular formula?

Accepted Answer

A)  2 
B)  4 
C)  8 
D)  6 
E)  7 
A)  2 
B)  4 
C)  8 
D)  6 
E)  7

Question 7

The average adult exhales about 1.0 kg of carbon dioxide each day. How much oxygen is needed in metabolizing glucose (C6H12O6, 180 g/mol) to make that much carbon dioxide?

Accepted Answer

A)  180 g 
B)  1800 g 
C)  360 g 
D)  730 g 
E)  1500 g 
A)  180 g 
B)  1800 g 
C)  360 g 
D)  730 g 
E)  1500 g

Question 8

Identify the list below that has these oxides arranged in order of increasing molar mass. Save time by looking at the periodic table and thinking, without actually doing any calculations.

Accepted Answer

A)  SO2 2 2 2 2 2 
C)  CO 2 2 2 
D)  NO 2 2 2 
E)  CO 2 2 2 
A)  SO2 2 2 2 2 2 
C)  CO 2 2 2 
D)  NO 2 2 2 
E)  CO 2 2 2

Question 9

Fe2O3(s) and powdered aluminum can react with great output of heat to form molten iron and Al2O3. When this reaction equation is balanced, what are the stoichiometric coefficients in the following order: Fe2O3, Al, Fe, Al2O3?

Accepted Answer

A)  1, 1, 1, 1 
B)  2, 2, 2, 2 
C)  1, 2, 2, 1 
D)  2, 1, 1, 2 
E)  1, 1, 2, 2 
A)  1, 1, 1, 1 
B)  2, 2, 2, 2 
C)  1, 2, 2, 1 
D)  2, 1, 1, 2 
E)  1, 1, 2, 2

Question 10

One form of asbestos called chrysotile is considered to be a human carcinogen. Mass analysis shows that the composition of chrysotile is 26.3% Mg, 20.2% Si, 1.45% H, and the remainder of the mass is oxygen. Determine the empirical formula of chrysotile.

Accepted Answer

A)  MgSiHO3 
B)  Mg2Si2H2O5 
C)  Mg3Si2H4O6 
D)  Mg3Si2H4O9 
E)  Mg4Si3H5O9 
A)  MgSiHO3 
B)  Mg2Si2H2O5 
C)  Mg3Si2H4O6 
D)  Mg3Si2H4O9 
E)  Mg4Si3H5O9

Question 11

Hydrogen peroxide decomposes to produce water and oxygen. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct?
2H2O2 $\rightarrow$2H2O + O2

Accepted Answer

A)  68.0 g $\rightarrow$36.0 g + 32.0 g 
B)  34.0 g $\rightarrow$18.0 g + 16.0 g 
C)  90.5 g$\rightarrow$47.9 g + 42.6 g 
D)  2x g $\rightarrow$2x g + x g 
E)  y(34.0 g) $\rightarrow$y(18.0 g) + (32 g)(y/2) 
A)  68.0 g $\rightarrow$36.0 g + 32.0 g 
B)  34.0 g $\rightarrow$18.0 g + 16.0 g 
C)  90.5 g$\rightarrow$47.9 g + 42.6 g 
D)  2x g $\rightarrow$2x g + x g 
E)  y(34.0 g) $\rightarrow$y(18.0 g) + (32 g)(y/2)

Question 12

Ammonia, NH3, is an important industrial chemical. It is produced using the Haber process from nitrogen, N2, and hydrogen, H2. How much ammonia can be produced from 28 kg of nitrogen and 2 kg of hydrogen, assuming the reaction yield is 90%?

Accepted Answer

A)  10.2 kg 
B)  11.3 kg 
C)  17.0 kg 
D)  34.0 kg 
E)  9.95 kg 
A)  10.2 kg 
B)  11.3 kg 
C)  17.0 kg 
D)  34.0 kg 
E)  9.95 kg

Question 13

A balanced chemical reaction equation is to a reactant as __________

Accepted Answer

A)  a map is to a gas station. 
B)  a child is to a parent. 
C)  a recipe is to an ingredient. 
D)  a good job is to a college degree. 
E)  a paycheck is to a job. 
A)  a map is to a gas station. 
B)  a child is to a parent. 
C)  a recipe is to an ingredient. 
D)  a good job is to a college degree. 
E)  a paycheck is to a job.

Question 14

Write the balanced reaction equation for the combustion of isooctane (C8H18), which is found in gasoline.

Accepted Answer

2C₈H₁₈ + 25O₂

Question 15

Calcium hydride (CaH2) is so reactive with water that it can be used to remove traces of water from solvents other than water. If 24.6 g of calcium hydride is added to a large volume of solvent that contains 14.0 g of water, which of these remains, water or calcium hydride, after the reaction is complete? The reaction is:
CaH2(s) + 2H2O(l) $\rightarrow$ Ca(OH)2(s) + 2H2(g)

Accepted Answer

A)  CaH2 will be left over. 
B)  Water will be left over. 
C)  Both will be completely consumed. 
D)  There is no way to tell. 
A)  CaH2 will be left over. 
B)  Water will be left over. 
C)  Both will be completely consumed. 
D)  There is no way to tell.

Question 16

Caffeine has an elemental analysis of 49.48% carbon, 5.190% hydrogen, 16.47% oxygen, and 28.85% nitrogen. It has a molar mass of 194.19 g/mol. What is the molecular formula of caffeine?

Accepted Answer

A)  C4H5N2O 
B)  C8H10N4O2 
C)  C10H14N2O2 
D)  C6H6NO2 
E)  C5H7NO 
A)  C4H5N2O 
B)  C8H10N4O2 
C)  C10H14N2O2 
D)  C6H6NO2 
E)  C5H7NO

Question 17

Which molecules shown below have the same empirical formula?

Accepted Answer

A)  II, III, IV are the same. 
B)  Only II and III are the same. 
C)  Only I and III are the same. 
D)  I, II, and III are the same. 
E)  I & III are the same, and II & IV are the same. 
A)  II, III, IV are the same. 
B)  Only II and III are the same. 
C)  Only I and III are the same. 
D)  I, II, and III are the same. 
E)  I & III are the same, and II & IV are the same.

Question 18

Write a definition of the phrase "stoichiometry of a chemical reaction."

Accepted Answer

"Stoichiometry of a chemical r

Question 19

Which statement about the following chemical reaction is not correct?
3H2 + N2 $\rightarrow$ 2NH3

Accepted Answer

A)  For every mole of nitrogen consumed, two moles of ammonia are produced. 
B)  For every two moles of nitrogen consumed, three moles of ammonia are produced. 
C)  For every three moles of hydrogen consumed, two moles of ammonia are produced. 
D)  For every two moles of ammonia produced, three moles of hydrogen are consumed. 
E)  Three moles of hydrogen will react with one mole of nitrogen to produce ammonia. 
A)  For every mole of nitrogen consumed, two moles of ammonia are produced. 
B)  For every two moles of nitrogen consumed, three moles of ammonia are produced. 
C)  For every three moles of hydrogen consumed, two moles of ammonia are produced. 
D)  For every two moles of ammonia produced, three moles of hydrogen are consumed. 
E)  Three moles of hydrogen will react with one mole of nitrogen to produce ammonia.

Question 20

The combustion of ethanol (CH3CH2OH, 46.1 g/mol) results in the formation of water and carbon dioxide. How many grams of carbon dioxide are produced when 46.1 g of ethanol burns?

Accepted Answer

A)  88.0 g 
B)  44.0 g 
C)  176 g 
D)  22.0 g 
E)  11.0 g 
A)  88.0 g 
B)  44.0 g 
C)  176 g 
D)  22.0 g 
E)  11.0 g

Exam 3: Stoichiometry: Mass, Formulas, and Reactions

Which statement, A-D, regarding the carbon cycle is not correct?

Glucose (C6H12O6) is oxidized by molecular oxygen to carbon dioxide and water. How many O2 molecules are needed for each molecule of glucose that is oxidized?

The mass of 0.25 mol of some element is 8.0 g. What is the element?

How many mL of C16H34 are needed to react with 0.050 mol O2, assuming complete combustion occurs? The density of C16H34 is 0.80 g/mL.

How many oxygen atoms are there in 27.0 g of sodium sulfate (Na2SO4)?

Chemical analysis of an organic compound found the following composition: 40.0% C, 53.5% O, and 6.7% H. If the molar mass is 180.2 g/mol, how many empirical formula units are there in the molecular formula?

The average adult exhales about 1.0 kg of carbon dioxide each day. How much oxygen is needed in metabolizing glucose (C6H12O6, 180 g/mol) to make that much carbon dioxide?

Identify the list below that has these oxides arranged in order of increasing molar mass. Save time by looking at the periodic table and thinking, without actually doing any calculations.

Fe2O3(s) and powdered aluminum can react with great output of heat to form molten iron and Al2O3. When this reaction equation is balanced, what are the stoichiometric coefficients in the following order: Fe2O3, Al, Fe, Al2O3?

One form of asbestos called chrysotile is considered to be a human carcinogen. Mass analysis shows that the composition of chrysotile is 26.3% Mg, 20.2% Si, 1.45% H, and the remainder of the mass is oxygen. Determine the empirical formula of chrysotile.

Hydrogen peroxide decomposes to produce water and oxygen. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct? 2H2O2 →\rightarrow→ 2H2O + O2

Ammonia, NH3, is an important industrial chemical. It is produced using the Haber process from nitrogen, N2, and hydrogen, H2. How much ammonia can be produced from 28 kg of nitrogen and 2 kg of hydrogen, assuming the reaction yield is 90%?

A balanced chemical reaction equation is to a reactant as __________

Write the balanced reaction equation for the combustion of isooctane (C8H18), which is found in gasoline.

Caffeine has an elemental analysis of 49.48% carbon, 5.190% hydrogen, 16.47% oxygen, and 28.85% nitrogen. It has a molar mass of 194.19 g/mol. What is the molecular formula of caffeine?

Which molecules shown below have the same empirical formula?

Write a definition of the phrase "stoichiometry of a chemical reaction."

Which statement about the following chemical reaction is not correct? 3H2 + N2 →\rightarrow→ 2NH3

The combustion of ethanol (CH3CH2OH, 46.1 g/mol) results in the formation of water and carbon dioxide. How many grams of carbon dioxide are produced when 46.1 g of ethanol burns?

Matter and Energy: The Origin of the Universe

Atoms, Ions, and Molecules: Matter Starts Here

Solution Chemistry: The Hydrosphere

Thermochemistry: Energy Changes in Reactions

Properties of Gases: the Air We Breathe

A Quantum Model of Atoms: Waves and Particles

Chemical Bonds: What Makes a Gas a Greenhouse Gas

Molecular Geometry: Shape Determines Function

Intermolecular Forces: The Uniqueness of Water

Solutions: Properties and Behavior

Solids: Structures and Applications

Organic Chemistry: Fuels, Pharmaceuticals, Materials, and Life

Chemical Kinetics: Reactions in the Air We Breathe

Chemical Equilibrium: How Much Product Does a Reaction Really Make

Acid-Base and Solubility Equilibria: Reactions in Soil and Water

Metal Ions: Colorful and Essential

Thermodynamics: Spontaneous and Nonspontaneous Reactions and Processes

Electrochemistry: the Quest for Clean Energy

Biochemistry: the Compounds of Life

Nuclear Chemistry: Applications to Energy and Medicine

Life and the Periodic Table

Filters

Glucose (C₆H₁₂O₆) is oxidized by molecular oxygen to carbon dioxide and water. How many O₂ molecules are needed for each molecule of glucose that is oxidized?

How many mL of C₁₆H₃₄ are needed to react with 0.050 mol O₂, assuming complete combustion occurs? The density of C₁₆H₃₄ is 0.80 g/mL.

How many oxygen atoms are there in 27.0 g of sodium sulfate (Na₂SO₄)?

The average adult exhales about 1.0 kg of carbon dioxide each day. How much oxygen is needed in metabolizing glucose (C₆H₁₂O₆, 180 g/mol) to make that much carbon dioxide?

Fe₂O₃(s) and powdered aluminum can react with great output of heat to form molten iron and Al₂O₃. When this reaction equation is balanced, what are the stoichiometric coefficients in the following order: Fe₂O₃, Al, Fe, Al₂O₃?

Hydrogen peroxide decomposes to produce water and oxygen. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct? 2H₂O₂ $\rightarrow$ 2H₂O + O₂

Ammonia, NH₃, is an important industrial chemical. It is produced using the Haber process from nitrogen, N₂, and hydrogen, H₂. How much ammonia can be produced from 28 kg of nitrogen and 2 kg of hydrogen, assuming the reaction yield is 90%?

Write the balanced reaction equation for the combustion of isooctane (C₈H₁₈), which is found in gasoline.

Which statement about the following chemical reaction is not correct? 3H₂ + N₂ $\rightarrow$ 2NH₃

The combustion of ethanol (CH₃CH₂OH, 46.1 g/mol) results in the formation of water and carbon dioxide. How many grams of carbon dioxide are produced when 46.1 g of ethanol burns?