Question 1

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

Question 2

In one type of fuel cell, methanol CH3OH) enters on one side of the unit and air enters on the other side.Both circulate past electrodes and chemically react to produce carbon dioxide and water along with electricity.Which chemical equation best represents the reaction that occurs?

Accepted Answer

A) CH3 OH(l) $\rightarrow$CO2 (g) + 2 H2 O(l) 
B) 2 CH3 OH(l) + 3 O2 (g) $\rightarrow$ 2 CO2 (g) + 4 H2 O(l) 
C) CH3 OH(l) $\rightarrow$ CH2 (g) + H2 O(l) 
D) CH3 OH(l) +N2(g) $\rightarrow$ CH3(g) + NO(g) 
E) CH3 OH(l) +O2(g) $\rightarrow$ CO2(g) + H2O(l)

Question 3

Hemlock contains a number of toxins, one of which is coniine.In a combustion experiment, 2.0000 g coniine was burned in excess oxygen to give 5.5343 g CO2 and 2.4080 g H2O.In a second experiment, it was determined that the compound is composed of only carbon, hydrogen, and nitrogen and its molar mass is less than 200 g/mol.Using the empirical formula of coniine, indicate how many atoms are in one molecule.For example, if the molecular formula were CNH2, you would respond 4.

Accepted Answer

A) 19 
B) 25 
C) 26 
D) 29 
E) 30

Question 4

A 2.0 kg bottle of sodium carbonate (Na2CO3, 106.0 g/mol) is available to clean up a 1665 g sulfuric acid spill (H2SO4, 98.08 g/mol).Is this enough sodium carbonate to neutralize the acid according to the following reaction? H2 SO4 (aq) + Na2 CO3 (s) $\rightarrow$ Na2 SO4 (aq) + CO2 (g) +H2 O(l)

Accepted Answer

A) Yes, there is about 50% more than what is needed. 
B) Yes, there is exactly enough sodium carbonate, but no excess. 
C) Yes, but there is only about 10% excess. 
D) No, there is not enough sodium carbonate, but the amount is only about 10% too small. 
E) No, there is not nearly enough sodium carbonate.

Question 5

Allicin is a potent antibacterial compound that is produced by an enzyme when garlic is chopped.Allicin contains carbon, hydrogen, oxygen, and sulfur atoms.In combustion analysis, 10.00 mg allicin produced 16.27 mg of CO2, 5.55 mg of water, and 7.90 mg of SO2.What is the empirical formula of allicin?

Accepted Answer

A) C6H10S2O 
B) C3H5SO 
C) C12H20S4O 
D) C6H10SO 
E) The moles of oxygen in the sample cannot be determined, so the empirical formula cannot be determined.

Question 6

n-Heptane (C₇H₁₆, 00.20 g/mol) is an undesirable component of gasoline because it burns explosively and contributes to engine "knocking." Write the balanced combustion reaction of C ₇H₁₆.Calculate the number of grams of C₇H₁₆ that react if 225 g CO₂ (44.01 g/mol) are produced.

Accepted Answer

The answer of n-Heptane (C₇H₁₆, 00.20 g/mol) is an undesirable...

Question 7

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

Accepted Answer

The answer of Write a definition of the phrase "stoichiometry...

Question 8

Chemical analysis of an organic compound found the following composition: 40.0% C, 53.29% O, and 6.71% H.If the molar mass is 90.08 g/mol, how many empirical formula units are there in the molecular formula?

Accepted Answer

A) 2 
B) 3 
C) 4 
D) 6 
E) 8

Question 9

Eugenol, a component of clove oil, is 73.15% C, 7.36% H, and 19.49% O; its molar mass is 164.19 g/mol.What is its molecular formula?

Accepted Answer

The answer of Eugenol, a component of clove oil, is...

Question 10

Sulfur dioxide from coal-fired power plants combines with water in the atmosphere to produce acid rain.What is the product when one molecule of SO2 reacts with one molecule of water?

Accepted Answer

A) two molecules of sulfurous acid 
B) one sulfate ion 
C) two sulfite ions 
D) one molecule of sulfuric acid 
E) one molecule of sulfurous acid

Question 11

Alkanes share a general chemical formula of Cn H2n+2 .What is n of an alkane with a molar mass in the range of 140-145 g/mol?

Accepted Answer

A) 10 
B) 9 
C) 8 
D) 11 
E) 12

Question 12

Global carbon emissions in 2010 were estimated to be on the order of 9.0 * 1012 metric tons of carbon 1 metric ton =1000 kg) in the form of CO2.This is equivalent to _______ kg C.

Accepted Answer

A) about 2.5 * 1015 
B) about 7.5 * 1014 
C) about 2.0 * 1014 
D) about 1.7 * 1013 
E) about 1.2 *1015

Question 13

Copper(II) sulfate (CuSO4) can be used to control algae growth.Aqueous CuSO4 solutions that come in contact with the surface of galvanized (zinc-plated) steel pails undergo the following reaction: 
CuSO4 (aq) +Zn(s) $\rightarrow$ Cu(s) +ZnSO4 (aq)
How many grams of zinc would react with 454 g (1 lb) of CuSO4 (159.61 g/mol)?

Accepted Answer

A) 467 g 
B) 186 g 
C) 93 g 
D) 234 g 
E) 454 g

Question 14

The most abundant metal in Earth's crust is aluminum, found mostly in the form of clays.Bauxite ore, impure hydrated aluminum oxide, can be purified and refined to make the metal.After the first purification step, hydrated aluminum oxide (Al2O3 .xH2O) is obtained.When 100.0 g of this solid was heated and the water driven off, 65.36 g of Al2O3 remained.How many water molecules (x in the molecular formula) were there in the hydrate?

Accepted Answer

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

Question 15

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

Question 16

One mole is defined as _______

Accepted Answer

A) the number of particles equal to the number of atoms in exactly 12 g of carbon-12. 
B) the number of particles equal to the number of atoms in exactly 16 g of oxygen-16. 
C) the number of particles equal to the number of molecules in 1kg of water. 
D) the number of particles equal to the number of atoms in exactly 1 g of hydrogen-1. 
E) the number of particles equal to the number of atoms in exactly 1 kg of carbon at the National Bureau of Standards.

Question 17

Which statement about a balanced chemical reaction equation is always correct?

Accepted Answer

A) The total number of moles of the products equals the total number of moles of the reactants. 
B) The number of atoms of each kind is the same for the products as for the reactants. 
C) The sum of the stoichiometric coefficients for the products equals the sum of the stoichiometric coefficients for the reactants. 
D) The sum of the masses of all gaseous products equals the sum of the masses of the gaseous reactants. 
E) The sum of the masses of solid products equals the sum of the masses of solid reactants.

Question 18

Phthalocyanine is a large molecule used in printing inks and dyes.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 its molecular formula?

Accepted Answer

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

Question 19

Fuming sulfuric acid is obtained by the addition of SO3 to concentrated H2SO4.The fumes result from the reaction of SO3 gas with water vapor.What is the product when one molecule of SO3 reacts with one molecule of water?

Accepted Answer

A) two molecules of sulfurous acid 
B) one sulfate ion 
C) two sulfite ions 
D) one molecule of sulfuric acid 
E) two molecules of sulfuric acid

Question 20

Some indoor air purification systems work by converting some of the oxygen in the air to ozone, which oxidizes mold, mildew spores, and other biological pollutants.One such system supposedly generates 5.0 g O₃ per hour by passing dry air through the purifier at a rate of 5.0 L/min.If 1.0 L of air contains 0.28 g of oxygen, what percent of the O₂ molecules are converted to O₃ molecules?

Accepted Answer

The answer of Some indoor air purification systems work by...

Exam 7: Stoichiometry Mass Relationships and Chemical Reactions

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?

In one type of fuel cell, methanol CH₃OH) enters on one side of the unit and air enters on the other side.Both circulate past electrodes and chemically react to produce carbon dioxide and water along with electricity.Which chemical equation best represents the reaction that occurs?

n-Heptane (C₇H₁₆, 00.20 g/mol) is an undesirable component of gasoline because it burns explosively and contributes to engine "knocking." Write the balanced combustion reaction of C ₇H₁₆.Calculate the number of grams of C₇H₁₆ that react if 225 g CO₂ (44.01 g/mol) are produced.

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

Chemical analysis of an organic compound found the following composition: 40.0% C, 53.29% O, and 6.71% H.If the molar mass is 90.08 g/mol, how many empirical formula units are there in the molecular formula?

Eugenol, a component of clove oil, is 73.15% C, 7.36% H, and 19.49% O; its molar mass is 164.19 g/mol.What is its molecular formula?

Sulfur dioxide from coal-fired power plants combines with water in the atmosphere to produce acid rain.What is the product when one molecule of SO₂ reacts with one molecule of water?

Alkanes share a general chemical formula of C_n H₂_n+2 .What is n of an alkane with a molar mass in the range of 140-145 g/mol?

Global carbon emissions in 2010 were estimated to be on the order of 9.0 * 10¹² metric tons of carbon 1 metric ton =1000 kg) in the form of CO₂.This is equivalent to _______ kg C.

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

One mole is defined as _______

Which statement about a balanced chemical reaction equation is always correct?

Phthalocyanine is a large molecule used in printing inks and dyes.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 its molecular formula?

Fuming sulfuric acid is obtained by the addition of SO₃ to concentrated H₂SO₄.The fumes result from the reaction of SO₃ gas with water vapor.What is the product when one molecule of SO₃ reacts with one molecule of water?

Exam 7: Stoichiometry Mass Relationships and Chemical Reactions

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?

In one type of fuel cell, methanol CH3OH) enters on one side of the unit and air enters on the other side.Both circulate past electrodes and chemically react to produce carbon dioxide and water along with electricity.Which chemical equation best represents the reaction that occurs?

n-Heptane (C7H16, 00.20 g/mol) is an undesirable component of gasoline because it burns explosively and contributes to engine "knocking." Write the balanced combustion reaction of C 7H16.Calculate the number of grams of C7H16 that react if 225 g CO2 (44.01 g/mol) are produced.

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

Chemical analysis of an organic compound found the following composition: 40.0% C, 53.29% O, and 6.71% H.If the molar mass is 90.08 g/mol, how many empirical formula units are there in the molecular formula?

Eugenol, a component of clove oil, is 73.15% C, 7.36% H, and 19.49% O; its molar mass is 164.19 g/mol.What is its molecular formula?

Sulfur dioxide from coal-fired power plants combines with water in the atmosphere to produce acid rain.What is the product when one molecule of SO2 reacts with one molecule of water?

Alkanes share a general chemical formula of Cn H2n+2 .What is n of an alkane with a molar mass in the range of 140-145 g/mol?

Global carbon emissions in 2010 were estimated to be on the order of 9.0 * 1012 metric tons of carbon 1 metric ton =1000 kg) in the form of CO2.This is equivalent to _______ kg C.

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

One mole is defined as _______

Which statement about a balanced chemical reaction equation is always correct?

Phthalocyanine is a large molecule used in printing inks and dyes.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 its molecular formula?

Fuming sulfuric acid is obtained by the addition of SO3 to concentrated H2SO4.The fumes result from the reaction of SO3 gas with water vapor.What is the product when one molecule of SO3 reacts with one molecule of water?

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?

In one type of fuel cell, methanol CH₃OH) enters on one side of the unit and air enters on the other side.Both circulate past electrodes and chemically react to produce carbon dioxide and water along with electricity.Which chemical equation best represents the reaction that occurs?

n-Heptane (C₇H₁₆, 00.20 g/mol) is an undesirable component of gasoline because it burns explosively and contributes to engine "knocking." Write the balanced combustion reaction of C ₇H₁₆.Calculate the number of grams of C₇H₁₆ that react if 225 g CO₂ (44.01 g/mol) are produced.

Sulfur dioxide from coal-fired power plants combines with water in the atmosphere to produce acid rain.What is the product when one molecule of SO₂ reacts with one molecule of water?

Alkanes share a general chemical formula of C_n H₂_n+2 .What is n of an alkane with a molar mass in the range of 140-145 g/mol?

Global carbon emissions in 2010 were estimated to be on the order of 9.0 * 10¹² metric tons of carbon 1 metric ton =1000 kg) in the form of CO₂.This is equivalent to _______ kg C.

Fuming sulfuric acid is obtained by the addition of SO₃ to concentrated H₂SO₄.The fumes result from the reaction of SO₃ gas with water vapor.What is the product when one molecule of SO₃ reacts with one molecule of water?