Question 1

Which of the following cartoons depict a balanced reaction?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 2

Nitrogen monoxide undergoes combustion to produce nitrogen dioxide. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct? 2NO   O2   2NO2

Accepted Answer

A) 2x g   x g   2x g 
B) 2 molecules   +1 molecule     2 molecules 
C) 60.0 g   32.0 g     92.0 g 
D) (2y)(30.0 g)   y (32.0 g)     (2y)(46.0 g) 
E) 15.0 g   8.0 g     23.0 g 
A) 2x g   x g   2x g 
B) 2 molecules   +1 molecule     2 molecules 
C) 60.0 g   32.0 g     92.0 g 
D) (2y)(30.0 g)   y (32.0 g)     (2y)(46.0 g) 
E) 15.0 g   8.0 g     23.0 g

Question 3

Without doing any calculations, identify which of the following compounds has the largest percent sodium by mass and which has the smallest. Explain your logic.
sodium oxide, Na2O; sodium hydroxide, NaOH; sodium hydrogen carbonate, NaHCO3;
sodium carbonate, Na2CO3; sodium peroxide, Na2O2

Accepted Answer

Sodium oxide has the largest percent sod

Question 4

Balance the following chemical equation:
C2H3OCl   O2   CO2 
    H2O   Cl2

Accepted Answer

4C<sub>2</sub>H<sub>

Question 5

At Sal's Sandwich Shop, a regular club sub is made using 2 slices of bread, 3 pieces of meat, and 1 cheese slice. How many club sandwiches can be made if there are 7 slices of bread, 10 pieces of meat, and 5 cheese slices?

Accepted Answer

A) 2 
B) 3 
C) 4 
D) 5 
E) 6 
A) 2 
B) 3 
C) 4 
D) 5 
E) 6

Question 6

When are an empirical formula and a molecular formula the same?

Accepted Answer

A) always 
B) when the mass of the empirical formula unit is equal to the molecular mass 
C) when the mass percentages of all of the elements in the two formulas are the same 
D) never 
E) when the molecular mass is an integer multiple of formula unit mass 
A) always 
B) when the mass of the empirical formula unit is equal to the molecular mass 
C) when the mass percentages of all of the elements in the two formulas are the same 
D) never 
E) when the molecular mass is an integer multiple of formula unit mass

Question 7

A compound known to contain platinum, nitrogen, and hydrogen was analyzed and found to contain 74.1% Pt and 21.3% N; the remainder was hydrogen. What is the empirical formula for the compound?

Accepted Answer

A) Pt(NH3)4 
B) Pt(NH3)3 
C) Pt2(NH3)2 
D) Pt(NH4)2 
E) Pt(NH3)6 
A) Pt(NH3)4 
B) Pt(NH3)3 
C) Pt2(NH3)2 
D) Pt(NH4)2 
E) Pt(NH3)6

Question 8

The average car emits 8.0 kg of carbon dioxide per gallon of combusted gas. What mass of gasoline (C8H18, 114.23 g/mol) was required to make that much carbon dioxide?

Accepted Answer

A) 5.0 $\times$10-3 kg 
B) 1.3 kg 
C) 2.6 kg 
D) 21 kg 
E) 170 kg 
A) 5.0 $\times$10-3 kg 
B) 1.3 kg 
C) 2.6 kg 
D) 21 kg 
E) 170 kg

Question 9

Phosphorus pentoxide is a common drying agent of organic molecules. Mass analysis reveals that it has the empirical formula P2O5. If the molar mass is 283.89 g/mol, which molecular formula is correct?

Accepted Answer

A) P2O5 
B) P3O4 
C) P4O10 
D) P5O6 
E) P6H15 
A) P2O5 
B) P3O4 
C) P4O10 
D) P5O6 
E) P6H15

Question 10

List three reasons why the actual yield for a chemical reaction may differ from the theoretical yield.

Accepted Answer

(1) The reactants and products reach an

Question 11

In one analysis, 1.34   1017 molecules of ozone (O3) were found in 2.00 mL of an air sample. How many moles of oxygen atoms is this?

Accepted Answer

A) 2.23   10-7 mol 
B) 8.07   1040 mol 
C) 6.68   10-7 mol 
D) 2.42   1041 mol 
E) 6.02   10-23 mol 
A) 2.23   10-7 mol 
B) 8.07   1040 mol 
C) 6.68   10-7 mol 
D) 2.42   1041 mol 
E) 6.02   10-23 mol

Question 12

Which statement about the following chemical reaction is not correct? 3H2    
N2 
     
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 13

Dialuminum hexachloride, Al2Cl6 (266.66 g/mol), is an inexpensive compound that is used in many industrial processes. It is made by treating scrap aluminum with chlorine gas. If a reaction is run with 270 g of aluminum and 710 grams of chlorine, the limiting reactant is ________, and the theoretical yield is ________ of Al2Cl6. 2Al(s)   3Cl2(g)   Al2Cl6(s)

Accepted Answer

A) Al; 890 g 
B) Cl2; 890 g 
C) Al; 1,300 g 
D) Cl2; 1,300 g 
E) Cl2; 2,700 g 
A) Al; 890 g 
B) Cl2; 890 g 
C) Al; 1,300 g 
D) Cl2; 1,300 g 
E) Cl2; 2,700 g

Question 14

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 15

Even though lead is toxic, lead compounds were used in ancient times as white pigments in cosmetics. What is the percentage of lead by mass in lead(IV) carbonate, Pb(CO3)2?

Accepted Answer

A) 32.7% 
B) 20.7% 
C) 63.3% 
D) 77.5% 
E) 81.4% 
A) 32.7% 
B) 20.7% 
C) 63.3% 
D) 77.5% 
E) 81.4%

Question 16

A burner in a gas grill mixes 20 volumes of air for every one volume of propane (C3H8). For gases at a given temperature and pressure, the volume that the gas occupies is directly proportional to the number of moles of the gas. Air is 21% oxygen by volume. Is the mixture produced by this burner rich (excess propane), lean (excess oxygen), or just right (a stoichiometric mixture of propane and oxygen)?

Accepted Answer

The mixture is too r

Question 17

How many hydrogen atoms are there in a 346 g sample of pure ammonia (NH3)?

Accepted Answer

A) 3.67   1025 atoms 
B) 1.22   1025 atoms 
C) 60.9 atoms 
D) 20.3 atoms 
E) 4.89   1025 atoms 
A) 3.67   1025 atoms 
B) 1.22   1025 atoms 
C) 60.9 atoms 
D) 20.3 atoms 
E) 4.89   1025 atoms

Question 18

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C16H34. Write the balanced reaction equation for the combustion of C16H34, and report the sum of the stoichiometric coefficients.

Accepted Answer

A) 4 
B) 120 
C) 76 
D) 83 
E) 117 
A) 4 
B) 120 
C) 76 
D) 83 
E) 117

Question 19

Phthalocyanine is a large molecule used in printing inks and dyes for clothing due to its insolubility in most solvents, its chemical stability, and its intense blue color. Elemental analysis showed that it consists of 74.69% C, 3.525% H, and 21.77% N, and has a molar mass of 514.54 g/mol. What is the molecular formula for phthalocyanine?

Accepted Answer

A) C16H9N4 
B) C30H8N10 
C) C32H18N8 
D) C32H4N9 
E) C16H18N4 
A) C16H9N4 
B) C30H8N10 
C) C32H18N8 
D) C32H4N9 
E) C16H18N4

Question 20

A particular manufacturer sells phosphoric acid capsules as a homeopathic remedy with a concentration specified as 23X. (23X means that when averaged over many capsules, the average mass of phosphoric acid in one capsule is 10-23 times the mass of the capsule. The rest is a carbohydrate filler.) If each capsule has a mass of 35 mg, approximately how many capsules would you have to take to expect to ingest at least one molecule of H3PO4 (98.0 g/mol)?

Accepted Answer

A) 1 
B) 5 
C) 50 
D) 500 
E) 5000 
A) 1 
B) 5 
C) 50 
D) 500 
E) 5000

Which of the following cartoons depict a balanced reaction?

Nitrogen monoxide undergoes combustion to produce nitrogen dioxide. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct? 2NO O₂ 2NO₂

Without doing any calculations, identify which of the following compounds has the largest percent sodium by mass and which has the smallest. Explain your logic. sodium oxide, Na₂O; sodium hydroxide, NaOH; sodium hydrogen carbonate, NaHCO₃; sodium carbonate, Na₂CO₃; sodium peroxide, Na₂O₂

Balance the following chemical equation: C₂H₃OCl O₂ CO₂ H₂O Cl₂

At Sal's Sandwich Shop, a regular club sub is made using 2 slices of bread, 3 pieces of meat, and 1 cheese slice. How many club sandwiches can be made if there are 7 slices of bread, 10 pieces of meat, and 5 cheese slices?

When are an empirical formula and a molecular formula the same?

A compound known to contain platinum, nitrogen, and hydrogen was analyzed and found to contain 74.1% Pt and 21.3% N; the remainder was hydrogen. What is the empirical formula for the compound?

The average car emits 8.0 kg of carbon dioxide per gallon of combusted gas. What mass of gasoline (C₈H₁₈, 114.23 g/mol) was required to make that much carbon dioxide?

Phosphorus pentoxide is a common drying agent of organic molecules. Mass analysis reveals that it has the empirical formula P₂O₅. If the molar mass is 283.89 g/mol, which molecular formula is correct?

List three reasons why the actual yield for a chemical reaction may differ from the theoretical yield.

In one analysis, 1.34 10¹⁷ molecules of ozone (O₃) were found in 2.00 mL of an air sample. How many moles of oxygen atoms is this?

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

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?

Even though lead is toxic, lead compounds were used in ancient times as white pigments in cosmetics. What is the percentage of lead by mass in lead(IV) carbonate, Pb(CO₃)₂?

How many hydrogen atoms are there in a 346 g sample of pure ammonia (NH₃)?

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C₁₆H₃₄. Write the balanced reaction equation for the combustion of C₁₆H₃₄, and report the sum of the stoichiometric coefficients.

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: Crystals, Alloys, and Polymers

Chemical Kinetics: Reactions in the Atmosphere

Chemical Equilibrium: How Much Product Does a Reaction Really Make

Acidbase Equilibria: Proton Transfer in Biological Systems

Additional Aqueous Equilibria: Chemistry and the Oceans

Thermodynamics: Spontaneous and Nonspontaneous Reactions and Processes

Electrochemistry: The Quest for Clean Energy

Nuclear Chemistry: Applications to Energy and Medicine

Organic and Biological Molecules: the Compounds of Life

The Main Group Elements: Life and the Periodic Table

Transition Metals: Biological and Medical Applications

Filters

Exam 3: Stoichiometry: Mass, Formulas, and Reactions

Which of the following cartoons depict a balanced reaction?

Nitrogen monoxide undergoes combustion to produce nitrogen dioxide. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct? 2NO O2 2NO2

Without doing any calculations, identify which of the following compounds has the largest percent sodium by mass and which has the smallest. Explain your logic. sodium oxide, Na2O; sodium hydroxide, NaOH; sodium hydrogen carbonate, NaHCO3; sodium carbonate, Na2CO3; sodium peroxide, Na2O2

Balance the following chemical equation: C2H3OCl O2 CO2 H2O Cl2

At Sal's Sandwich Shop, a regular club sub is made using 2 slices of bread, 3 pieces of meat, and 1 cheese slice. How many club sandwiches can be made if there are 7 slices of bread, 10 pieces of meat, and 5 cheese slices?

When are an empirical formula and a molecular formula the same?

A compound known to contain platinum, nitrogen, and hydrogen was analyzed and found to contain 74.1% Pt and 21.3% N; the remainder was hydrogen. What is the empirical formula for the compound?

The average car emits 8.0 kg of carbon dioxide per gallon of combusted gas. What mass of gasoline (C8H18, 114.23 g/mol) was required to make that much carbon dioxide?

Phosphorus pentoxide is a common drying agent of organic molecules. Mass analysis reveals that it has the empirical formula P2O5. If the molar mass is 283.89 g/mol, which molecular formula is correct?

List three reasons why the actual yield for a chemical reaction may differ from the theoretical yield.

In one analysis, 1.34 1017 molecules of ozone (O3) were found in 2.00 mL of an air sample. How many moles of oxygen atoms is this?

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

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?

Even though lead is toxic, lead compounds were used in ancient times as white pigments in cosmetics. What is the percentage of lead by mass in lead(IV) carbonate, Pb(CO3)2?

How many hydrogen atoms are there in a 346 g sample of pure ammonia (NH3)?

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C16H34. Write the balanced reaction equation for the combustion of C16H34, and report the sum of the stoichiometric coefficients.

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: Crystals, Alloys, and Polymers

Chemical Kinetics: Reactions in the Atmosphere

Chemical Equilibrium: How Much Product Does a Reaction Really Make

Acidbase Equilibria: Proton Transfer in Biological Systems

Additional Aqueous Equilibria: Chemistry and the Oceans

Thermodynamics: Spontaneous and Nonspontaneous Reactions and Processes

Electrochemistry: The Quest for Clean Energy

Nuclear Chemistry: Applications to Energy and Medicine

Organic and Biological Molecules: the Compounds of Life

The Main Group Elements: Life and the Periodic Table

Transition Metals: Biological and Medical Applications

Filters

Nitrogen monoxide undergoes combustion to produce nitrogen dioxide. Which relationship regarding the quantities of reactants and products associated with this reaction is not correct? 2NO O₂ 2NO₂

Balance the following chemical equation: C₂H₃OCl O₂ CO₂ H₂O Cl₂

The average car emits 8.0 kg of carbon dioxide per gallon of combusted gas. What mass of gasoline (C₈H₁₈, 114.23 g/mol) was required to make that much carbon dioxide?

Phosphorus pentoxide is a common drying agent of organic molecules. Mass analysis reveals that it has the empirical formula P₂O₅. If the molar mass is 283.89 g/mol, which molecular formula is correct?

In one analysis, 1.34 10¹⁷ molecules of ozone (O₃) were found in 2.00 mL of an air sample. How many moles of oxygen atoms is this?

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

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?

Even though lead is toxic, lead compounds were used in ancient times as white pigments in cosmetics. What is the percentage of lead by mass in lead(IV) carbonate, Pb(CO₃)₂?

How many hydrogen atoms are there in a 346 g sample of pure ammonia (NH₃)?

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C₁₆H₃₄. Write the balanced reaction equation for the combustion of C₁₆H₃₄, and report the sum of the stoichiometric coefficients.