Question 1

According to the following reaction, which molecule is acting as an acid? H3O+ + HSO4- → H2O + H2SO4

Accepted Answer

A) H2SO4 
B) H2O 
C) H3O+ 
D) HSO4- 
E) none of the above 
A) H2SO4 
B) H2O 
C) H3O+ 
D) HSO4- 
E) none of the above

Question 2

How many electrons are gained or lost in the following half-reaction? Cl2 → 2 Cl-

Accepted Answer

A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained 
A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained

Question 3

According to the following reaction, which molecule is acting as a base? H3O+ + HSO4- → H2O + H2SO4

Accepted Answer

A) H2SO4 
B) H2O 
C) H3O+ 
D) HSO4- 
E) none of the above 
A) H2SO4 
B) H2O 
C) H3O+ 
D) HSO4- 
E) none of the above

Question 4

Which of the following statements describes a neutral solution?

Accepted Answer

A) [H3O+] > [OH-] 
B) [H3O+] -] 
C) [H3O+] × [OH-] ≠ 1 × 10-14 
D) [H3O+]/[OH-] = 1 × 10-14 
E) [H3O+]/[OH-] = 1 
A) [H3O+] > [OH-] 
B) [H3O+] -] 
C) [H3O+] × [OH-] ≠ 1 × 10-14 
D) [H3O+]/[OH-] = 1 × 10-14 
E) [H3O+]/[OH-] = 1

Question 5

For the following acid-base reaction, identify which salt is formed. HCl + NaOH ⇌ ???? + H2O

Accepted Answer

A) NaCl 
B) H3OCl 
C) NaOH2 
D) NaOH2Cl 
E) none of the above 
A) NaCl 
B) H3OCl 
C) NaOH2 
D) NaOH2Cl 
E) none of the above

Question 6

According to the following reaction, which molecule is acting as a base? OH- + NH4+ → H2O + NH3

Accepted Answer

A) H2O 
B) NH3 
C) OH- 
D) NH4+ 
E) none of the above 
A) H2O 
B) NH3 
C) OH- 
D) NH4+ 
E) none of the above

Question 7

Why is oxygen usually an oxidizing agent?

Accepted Answer

A) It is a very electronegative element. 
B) It does not undergo reduction. 
C) It likes to be oxidized. 
D) It is very abundant and so it is easier to react than nitrogen. 
E) all of the above 
A) It is a very electronegative element. 
B) It does not undergo reduction. 
C) It likes to be oxidized. 
D) It is very abundant and so it is easier to react than nitrogen. 
E) all of the above

Question 8

Why is the formation of iron hydroxide, Fe(OH)2, from Fe2+ and OH- not considered an oxidation-reduction reaction?

Accepted Answer

A) The iron is only oxidized and nothing is reduced. 
B) The iron is only reduced, not oxidized. 
C) The Fe2+ ion is not changed during this chemical reaction. 
D) Iron can never be oxidized or reduced. 
A) The iron is only oxidized and nothing is reduced. 
B) The iron is only reduced, not oxidized. 
C) The Fe2+ ion is not changed during this chemical reaction. 
D) Iron can never be oxidized or reduced.

Question 9

For the following acid-base reaction, identify what is formed in the space marked. HF + KOH ⇌ ???? + H2O

Accepted Answer

A) KF 
B) H3OF 
C) KOH2 
D) KOH2F 
E) none of the above 
A) KF 
B) H3OF 
C) KOH2 
D) KOH2F 
E) none of the above

Question 10

According to the following reaction, which molecule is acting as an acid? H2O + NH3 → OH- + NH4+

Accepted Answer

A) H2O 
B) NH3 
C) OH- 
D) NH4+ 
E) none of the above 
A) H2O 
B) NH3 
C) OH- 
D) NH4+ 
E) none of the above

Question 11

In a battery, the following oxidation-reduction reactions are taking place: Mn2O3 + ZnO → 2 MnO2 + Zn
What is being formed at the cathode?

Accepted Answer

A) Zn 
B) ZnO 
C) MnO2 
D) Mn2O3 
E) none of the above 
A) Zn 
B) ZnO 
C) MnO2 
D) Mn2O3 
E) none of the above

Question 12

A major source of chlorine gas, Cl2, is from the electrolysis of brine, which is concentrated salt water, NaCl (aq). What is the sign of the electrode where the chlorine gas is formed? Is it negative or positive?

Accepted Answer

A) Positive, since the chloride ions lose electrons to form chlorine molecules. 
B) Negative, since the chlorine gas needs to deposit electrons to form chloride ions. 
C) Neither, since chlorine gas is a neutral molecule, there is not electrode attraction. 
D) Both, since the chloride ions from NaCl (aq)are attracted to the positive electrode to form chlorine molecules while the produced chlorine gas molecules move to deposit electrons at the negative electrode. 
A) Positive, since the chloride ions lose electrons to form chlorine molecules. 
B) Negative, since the chlorine gas needs to deposit electrons to form chloride ions. 
C) Neither, since chlorine gas is a neutral molecule, there is not electrode attraction. 
D) Both, since the chloride ions from NaCl (aq)are attracted to the positive electrode to form chlorine molecules while the produced chlorine gas molecules move to deposit electrons at the negative electrode.

Question 13

A weak acid is added to a concentrated solution of hydrochloric acid. Does the solution become more or less acidic?

Accepted Answer

A) More acidic, since there are more hydronium ions being added to the solution. 
B) Less acidic, since the solution becomes more dilute with a less concentrated solution of hydronium ions being added to the solution. 
C) No change in acidity, since the concentration of the hydrochloric acid is too high to be changed by the weak solution. 
D) Less acidic since the concentration of hydroxide ions will increase. 
A) More acidic, since there are more hydronium ions being added to the solution. 
B) Less acidic, since the solution becomes more dilute with a less concentrated solution of hydronium ions being added to the solution. 
C) No change in acidity, since the concentration of the hydrochloric acid is too high to be changed by the weak solution. 
D) Less acidic since the concentration of hydroxide ions will increase.

Question 14

How many electrons are gained or lost in the following half-reaction? Zn → Zn+2

Accepted Answer

A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained 
A) 2 electrons are lost 
B) 1/2 electron is gained 
C) 1/2 electron is lost 
D) 2 electrons are gained 
E) 4 electrons are gained

Question 15

Qualitatively, what happens to the hydroxide ion concentration if you decrease the hydronium ion concentration?

Accepted Answer

A) The concentration of OH- stays the same but the ratio OH-/H3O+ changes. 
B) The concentration of OH- increases but the ratio stays the same. 
C) The concentration of OH- increases. 
D) none of the above 
A) The concentration of OH- stays the same but the ratio OH-/H3O+ changes. 
B) The concentration of OH- increases but the ratio stays the same. 
C) The concentration of OH- increases. 
D) none of the above

Question 16

Why is recycling of aluminum better for the environment than electrolysis of bauxite (an aluminum ore)?

Accepted Answer

A) It takes less energy to recycle aluminum. 
B) Electrolysis releases harmful gases into the atmosphere. 
C) The bauxite is extremely rare and there is very little aluminum in the world. 
D) Electricity is extremely cheap and it is better to use cheap electricity. 
E) none of the above 
A) It takes less energy to recycle aluminum. 
B) Electrolysis releases harmful gases into the atmosphere. 
C) The bauxite is extremely rare and there is very little aluminum in the world. 
D) Electricity is extremely cheap and it is better to use cheap electricity. 
E) none of the above

Question 17

Why might an area with a large amount of limestone (CaCO3)be less susceptible to acid rain?

Accepted Answer

A) The acid in the rain is neutralized by the natural base in the limestone. 
B) The rain travels quickly through the porous limestone and therefore the rate of reaction is slower. 
C) Limestone is degraded by acid rain and therefore acid rain has the same damaging effects. 
D) Only acid rain made from sulfur compounds reacts with the limestone. 
E) none of the above 
A) The acid in the rain is neutralized by the natural base in the limestone. 
B) The rain travels quickly through the porous limestone and therefore the rate of reaction is slower. 
C) Limestone is degraded by acid rain and therefore acid rain has the same damaging effects. 
D) Only acid rain made from sulfur compounds reacts with the limestone. 
E) none of the above

Question 18

In a battery, the following two oxidation-reduction reactions are taking place: rxn A: Zn + 2 OH- → ZnO + H2O + 2e- 
Rxn B: 2 MnO2 + H2O + 2e- → Mn2O3 + 2 OH-
What is undergoing reduction?

Accepted Answer

A) Zn 
B) ZnO 
C) MnO2 
D) H2O 
E) OH- 
A) Zn 
B) ZnO 
C) MnO2 
D) H2O 
E) OH-

Question 19

Why are combustion reactions generally exothermic?

Accepted Answer

A) Hydrogen easily pulls electrons from the oxygen in water molecules and are reduced. 
B) During combustion oxygen is oxidized, which gives off lots of energy. 
C) Combustion involves the transfer of electrons to oxygen, which has an extremely high tendency for gaining electrons. 
D) It is highly exothermic because combustion involves an oxidation-reduction reaction between a metallic material and oxygen. 
A) Hydrogen easily pulls electrons from the oxygen in water molecules and are reduced. 
B) During combustion oxygen is oxidized, which gives off lots of energy. 
C) Combustion involves the transfer of electrons to oxygen, which has an extremely high tendency for gaining electrons. 
D) It is highly exothermic because combustion involves an oxidation-reduction reaction between a metallic material and oxygen.

Question 20

Which of the following describes an electrode?

Accepted Answer

A) Any material that conducts electrons into a media where electrochemical reactions are taking place. 
B) Any material that conducts electrons out of a media where electrochemical reactions are taking place. 
C) Any material that conducts electrons. 
D) Any material that is undergoing an oxidation-reduction reaction in a battery. 
E) either A or B 
A) Any material that conducts electrons into a media where electrochemical reactions are taking place. 
B) Any material that conducts electrons out of a media where electrochemical reactions are taking place. 
C) Any material that conducts electrons. 
D) Any material that is undergoing an oxidation-reduction reaction in a battery. 
E) either A or B

Exam 18: Two Classes of Chemical Reactions

According to the following reaction, which molecule is acting as an acid? H3O+ + HSO4- → H2O + H2SO4

How many electrons are gained or lost in the following half-reaction? Cl2 → 2 Cl-

According to the following reaction, which molecule is acting as a base? H3O+ + HSO4- → H2O + H2SO4

Which of the following statements describes a neutral solution?

For the following acid-base reaction, identify which salt is formed. HCl + NaOH ⇌ ???? + H2O

According to the following reaction, which molecule is acting as a base? OH- + NH4+ → H2O + NH3

Why is oxygen usually an oxidizing agent?

Why is the formation of iron hydroxide, Fe(OH)2, from Fe2+ and OH- not considered an oxidation-reduction reaction?

For the following acid-base reaction, identify what is formed in the space marked. HF + KOH ⇌ ???? + H2O

According to the following reaction, which molecule is acting as an acid? H2O + NH3 → OH- + NH4+

In a battery, the following oxidation-reduction reactions are taking place: Mn2O3 + ZnO → 2 MnO2 + Zn What is being formed at the cathode?

A major source of chlorine gas, Cl2, is from the electrolysis of brine, which is concentrated salt water, NaCl (aq). What is the sign of the electrode where the chlorine gas is formed? Is it negative or positive?

A weak acid is added to a concentrated solution of hydrochloric acid. Does the solution become more or less acidic?

How many electrons are gained or lost in the following half-reaction? Zn → Zn+2

Qualitatively, what happens to the hydroxide ion concentration if you decrease the hydronium ion concentration?

Why is recycling of aluminum better for the environment than electrolysis of bauxite (an aluminum ore)?

Why might an area with a large amount of limestone (CaCO3)be less susceptible to acid rain?

In a battery, the following two oxidation-reduction reactions are taking place: rxn A: Zn + 2 OH- → ZnO + H2O + 2e- Rxn B: 2 MnO2 + H2O + 2e- → Mn2O3 + 2 OH- What is undergoing reduction?

Why are combustion reactions generally exothermic?

Which of the following describes an electrode?

Patterns of Motion and Equilibrium

Newtons Laws of Motion

Momentum and Energy

Gravity, Projectiles, and Satellites

Fluid Mechanics

Thermal Energy and Thermodynamics

Heat Transfer and Change of Phase

Static and Current Electricity

Magnetism and Electromagnetic Induction

Waves and Sound

Light

Atoms and the Periodic Table

The Atomic Nucleus and Radioactivity

Elements of Chemistry

How Atoms Bond and Molecules Attract

Mixtures

How Chemicals React

Organic Compounds

Rocks and Minerals

Plate Tectonics and Earths Interior

Shaping Earths Surface

Geologic Timereading the Rock Record

The Oceans, Atmosphere, and Climatic Effects

Driving Forces of Weather

The Solar System

Stars and Galaxies

The Structure of Space and Time

Prologue: the Nature of Science

Filters

According to the following reaction, which molecule is acting as an acid? H₃O⁺ + HSO₄^- → H₂O + H₂SO₄

How many electrons are gained or lost in the following half-reaction? Cl₂ → 2 Cl^-

According to the following reaction, which molecule is acting as a base? H₃O⁺ + HSO₄^- → H₂O + H₂SO₄

For the following acid-base reaction, identify which salt is formed. HCl + NaOH ⇌ ???? + H₂O

According to the following reaction, which molecule is acting as a base? OH^- + NH₄⁺ → H₂O + NH₃

Why is the formation of iron hydroxide, Fe(OH)₂, from Fe²⁺ and OH^- not considered an oxidation-reduction reaction?

For the following acid-base reaction, identify what is formed in the space marked. HF + KOH ⇌ ???? + H₂O

According to the following reaction, which molecule is acting as an acid? H₂O + NH₃ → OH^- + NH₄⁺

In a battery, the following oxidation-reduction reactions are taking place: Mn₂O₃ + ZnO → 2 MnO₂ + Zn What is being formed at the cathode?

A major source of chlorine gas, Cl₂, is from the electrolysis of brine, which is concentrated salt water, NaCl (aq). What is the sign of the electrode where the chlorine gas is formed? Is it negative or positive?

How many electrons are gained or lost in the following half-reaction? Zn → Zn⁺²

Why might an area with a large amount of limestone (CaCO₃)be less susceptible to acid rain?

In a battery, the following two oxidation-reduction reactions are taking place: rxn A: Zn + 2 OH^- → ZnO + H₂O + 2e^- Rxn B: 2 MnO₂ + H₂O + 2e^- → Mn₂O₃+ 2 OH^- What is undergoing reduction?