Question 1

When a hydronium ion concentration equals 1 × 10-10 moles per liter, what is the pH of the solution? Is the solution acidic or basic?

Accepted Answer

A) The pH of this solution is 4, which is acidic. 
B) The pH of this solution is 8, which is basic. 
C) The pH of this solution is 6, which is acidic. 
D) The pH of this solution is 10, which is basic.

Question 2

Why do we use the pH scale to indicate the acidity of a solution rather than simply stating the concentration of hydronium ions?

Accepted Answer

A) It includes the concentration of hydronium and hydroxide ions. 
B) It is used because the general public understands it. 
C) It is more accurate to use the pH scale. 
D) It is more convenient, since the concentration of hydronium ions is so small.

Question 3

In one type of fuel cell the following oxidation-reduction reactions are taking place: 2 H2 + O2 → 2 H2O
What is the fuel?

Accepted Answer

A) H2 
B) O2 
C) H2O 
D) all of the above 
E) none of the above

Question 4

The oxidation of iron to rust is a problem structural engineers need to be concerned about, but the oxidation of aluminum to aluminum oxide is not so much of a problem. Why?

Accepted Answer

A) Since aluminum is so light and inexpensive, it is easily replaced when corroded. 
B) Aluminum oxide is insoluble in water and thus forms a protective coating that prevents continued oxidation of the aluminum. 
C) Aluminum oxide is even stronger than aluminum. 
D) The oxidation of aluminum is a very slow reaction, taking hundreds of years before any structural changes are noticed.

Question 5

What would the concentration of OH- be if the concentration of H3O+ was 1 × 10-5M? [H3O+] × [OH-] = Kw = 1 × 10-14

Accepted Answer

A) 1 × 10-14 
B) 1 × 10-5 
C) 1 × 109 
D) 1 × 105 
E) 1 × 10-9

Question 6

What is an acid?

Accepted Answer

A) Anything that donates hydrogen ions. 
B) Anything that accepts hydrogen atoms. 
C) Anything that donates hydrogen atoms. 
D) Anything that dissolves metal. 
E) Anything that donates hydronium ions.

Question 7

What would be the best explanation for the fact that most natural water has a pH of about 5.6?

Accepted Answer

A) Carbon dioxide reacts with water to form an acid. 
B) Air contains acid rain particles. 
C) Minerals that are dissolved in water are often acidic. 
D) Many salts that dissolve in natural waters make the water basic. 
E) none of the above

Question 8

What would the concentration of H3O+ be if the concentration of OH- was 1 × 10-11M? [H3O+] × [OH-] = Kw = 1 × 10-14

Accepted Answer

A) 1 × 10-3 
B) 1 × 103 
C) 1 × 1014 
D) 1 × 1012 
E) 1 × 10-6

Question 9

What might the relationship be between an element's electronegativity and its ability to behave as an oxidizing agent?

Accepted Answer

A) As the electronegativity goes up the ability of an element to act as an oxidant increases. 
B) As the electronegativity goes up the ability of an element to act as an oxidant decreases. 
C) As the electronegativity goes up the ability of an element to act as an oxidant stays the same. 
D) As the electronegativity increases the element has a tendency to undergo oxidation. 
E) none of the above

Question 10

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

Accepted Answer

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

Question 11

Jewelry is often manufactured by electroplating an expensive metal such as gold over a cheaper metal. A setup for this process can be sketched as follows:  What would happen if the battery connections were suddenly reversed?

Accepted Answer

A) The ring would continue to electroplate with gold. 
B) Gold ions in solution would get reduced and settle to the bottom of the container. 
C) Gold ions in solution would begin to electroplate onto the gold electrode. 
D) All electrolysis would stop.

Question 12

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H3PO4 + H2O ⇌ H2PO4- + H3O+

Accepted Answer

A) acid 
B) base 
C) neither 
D) both 
E) none of the above

Question 13

What is the purpose of the salt bridge in a voltaic cell?

Accepted Answer

A) to prevent any further migration of electrons through the wire 
B) to allow for the build up of positively charged ions in one container and negatively charged ions in the other container 
C) to allow the Fe2+ and the Cu2+ to flow freely between the two containers 
D) to allow for a balance of charge between the two chambers

Question 14

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

Accepted Answer

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

Question 15

Along with the pH scale, there is the pOH scale, which indicates the level of "basicity" in a solution. Accordingly, pOH = -log[OH-]. What is the sum of the pH and the pOH of a solution always equal to?

Accepted Answer

A) the negative of the product of the hydronium and hydroxide ions 
B) the negative log of Kw, which is 14 
C) The sum would equal 7, since that would be neutral for pH and pOH. 
D) It is not constant because it depends on the acid/base solution in question.

Question 16

Aluminum metal undergoes the same basic corrosion process that iron does yet it does not decompose as rapidly. Why?

Accepted Answer

A) The aluminum oxide does not flake off like rust and acts as a protective layer. 
B) Aluminum is harder to oxidize than iron. 
C) Aluminum is harder to reduce than iron. 
D) The aluminum oxide product undergoes a reduction to produce aluminum metal. 
E) The aluminum is galvanized, which prevents oxidation.

Question 17

The following set of redox reactions takes place as shown. Container A Container B
Fe → Fe+2 + 2e- Cu +2 + 2e- → Cu
If you had two containers filled with the ion solution described above with a wire connecting a piece of iron (in container A) and a piece of copper (in container B) and a salt-bridge connecting the two containers, which way do the positive ions in the salt-bridge flow?

Accepted Answer

A)  There is no flow of positive ions in the salt-bridge 
B)  The positive ions flow from container A to container B. 
C)  The positive ions flow from container B to container A. 
D)  The positive ions flow back and forth between the two containers. 
E)  The ions only move in the containers they originate in.

Question 18

What is the main characteristic of a strong base?

Accepted Answer

A) It is completely dissociated in water. 
B) It readily accepts an acidic proton. 
C) It is corrosive. 
D) It will damage your skin. 
E) all of the above

Question 19

How does connecting a metal like iron with a wire to a metal that is easier to oxidize like zinc help prevent corrosion of the iron?

Accepted Answer

A) The other metal is oxidized instead and the electrons travel to the iron, keeping it from oxidizing. 
B) The other metal absorbs the electrons from the iron, which keeps the iron from undergoing oxidation. 
C) The wire is acting as an oxidant and keeps the two metals from undergoing other chemical reactions. 
D) There is no salt-bridge, so there is no reaction between the two metals. 
E) The other metal is oxidized and adsorbs all the oxidant, keeping it away from the iron.

Question 20

As the hydronium ion concentration increases, the pH ________.

Accepted Answer

A) goes down 
B) gets larger 
C) starts to affect the OH- concentration 
D) starts to alter the chemical properties of the water molecules 
E) stays constant

Exam 18: Two Classes of Chemical Reactions

When a hydronium ion concentration equals 1 × 10^-10 moles per liter, what is the pH of the solution? Is the solution acidic or basic?

Why do we use the pH scale to indicate the acidity of a solution rather than simply stating the concentration of hydronium ions?

In one type of fuel cell the following oxidation-reduction reactions are taking place: 2 H₂ + O₂ → 2 H₂O What is the fuel?

The oxidation of iron to rust is a problem structural engineers need to be concerned about, but the oxidation of aluminum to aluminum oxide is not so much of a problem. Why?

What would the concentration of OH^- be if the concentration of H₃O⁺ was 1 × 10^-⁵M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14

What is an acid?

What would be the best explanation for the fact that most natural water has a pH of about 5.6?

What would the concentration of H₃O⁺ be if the concentration of OH^- was 1 × 10^-11M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14

What might the relationship be between an element's electronegativity and its ability to behave as an oxidizing agent?

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

Jewelry is often manufactured by electroplating an expensive metal such as gold over a cheaper metal. A setup for this process can be sketched as follows: What would happen if the battery connections were suddenly reversed?

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H₃PO₄ + H₂O ⇌ H₂PO₄^- + H₃O⁺

What is the purpose of the salt bridge in a voltaic cell?

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

Along with the pH scale, there is the pOH scale, which indicates the level of "basicity" in a solution. Accordingly, pOH = -log[OH^-]. What is the sum of the pH and the pOH of a solution always equal to?

Aluminum metal undergoes the same basic corrosion process that iron does yet it does not decompose as rapidly. Why?

What is the main characteristic of a strong base?

How does connecting a metal like iron with a wire to a metal that is easier to oxidize like zinc help prevent corrosion of the iron?

As the hydronium ion concentration increases, the pH ________.

Exam 18: Two Classes of Chemical Reactions

When a hydronium ion concentration equals 1 × 10-10 moles per liter, what is the pH of the solution? Is the solution acidic or basic?

Why do we use the pH scale to indicate the acidity of a solution rather than simply stating the concentration of hydronium ions?

In one type of fuel cell the following oxidation-reduction reactions are taking place: 2 H2 + O2 → 2 H2O What is the fuel?

The oxidation of iron to rust is a problem structural engineers need to be concerned about, but the oxidation of aluminum to aluminum oxide is not so much of a problem. Why?

What would the concentration of OH- be if the concentration of H3O+ was 1 × 10-5M? [H3O+] × [OH-] = Kw = 1 × 10-14

What is an acid?

What would be the best explanation for the fact that most natural water has a pH of about 5.6?

What would the concentration of H3O+ be if the concentration of OH- was 1 × 10-11M? [H3O+] × [OH-] = Kw = 1 × 10-14

What might the relationship be between an element's electronegativity and its ability to behave as an oxidizing agent?

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

Jewelry is often manufactured by electroplating an expensive metal such as gold over a cheaper metal. A setup for this process can be sketched as follows: What would happen if the battery connections were suddenly reversed?

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H3PO4 + H2O ⇌ H2PO4- + H3O+

What is the purpose of the salt bridge in a voltaic cell?

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

Along with the pH scale, there is the pOH scale, which indicates the level of "basicity" in a solution. Accordingly, pOH = -log[OH-]. What is the sum of the pH and the pOH of a solution always equal to?

Aluminum metal undergoes the same basic corrosion process that iron does yet it does not decompose as rapidly. Why?

What is the main characteristic of a strong base?

How does connecting a metal like iron with a wire to a metal that is easier to oxidize like zinc help prevent corrosion of the iron?

As the hydronium ion concentration increases, the pH ________.

When a hydronium ion concentration equals 1 × 10^-10 moles per liter, what is the pH of the solution? Is the solution acidic or basic?

In one type of fuel cell the following oxidation-reduction reactions are taking place: 2 H₂ + O₂ → 2 H₂O What is the fuel?

What would the concentration of OH^- be if the concentration of H₃O⁺ was 1 × 10^-⁵M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14

What would the concentration of H₃O⁺ be if the concentration of OH^- was 1 × 10^-11M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14

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

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H₃PO₄ + H₂O ⇌ H₂PO₄^- + H₃O⁺

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

Along with the pH scale, there is the pOH scale, which indicates the level of "basicity" in a solution. Accordingly, pOH = -log[OH^-]. What is the sum of the pH and the pOH of a solution always equal to?