Question 1

Find the correct statement:

Accepted Answer

A)   Oxidizing agent oxidizes another species and is reduced during a redox reaction.
B)   Half-reactions represent actual chemical processes
C)   During a reduction process, a reducing agent releases electron(s) .D) All of the above
E) B) and C)

Question 2

Find the correct statement about Latimer diagrams and one of their uses:

Accepted Answer

A)   In Latimer diagrams the oxidation numbers increase from left to right; a species can disproportionate into its two neighbours if the potential on the right is more negative than the potential on the left.
B)   In Latimer diagrams the oxidation numbers decrease from left to right; a species can disproportionate into its two neighbours if the potential on the right is more negative than the potential on the left.
C)   In Latimer diagrams the oxidation numbers decrease from left to right; a species can disproportionate into its two neighbours if the potential on the right is more positive than the potential on the left.D) None of the above
E) All of the above

Question 3

Which statement is the correct one?

Accepted Answer

A)   Comproportionation is a redox reaction in which the oxidation number of an element is simultaneously raised and lowered. Disproportionation is the opposite of comproportionation.
B)   Disproportionation is a reaction in which the oxidation number of an element is raised. Comproportionation is a reaction in which the oxidation number of an element is lowered.
C)   Disproportionation is a redox reaction in which the oxidation number of an element is simultaneously raised and lowered. Comproportionation is the opposite of disproportionation.D) A) and B)
E) A) and C)

Question 4

Find the correct statement(s)  concerning the Pourbaix diagrams:
(i)  A horizontal line separates species related by proton transfer only
(ii)  A vertical line separates species related by electron transfer only
(iii)  Sloped lines separate species related by both electron and proton transfer.

Accepted Answer

A)   All are correct
B)   (i)  and (ii) 
C)   Only (iii) D) A) and C)
E) A) and B)

Question 5

Determine the oxidation states of sulfur in the following compounds (i)  H2S (ii)  SO2 and (iii)  H2SO3.

Accepted Answer

A)   (i)  -2 (ii)  +4 (iii)  +6.
B)   (i)  +2 (ii)  +4 (iii)  + 6.
C)   (i)  -2 (ii)  +4 (iii)  +4.D) B) and C)
E) All of the above C

Question 6

A redox reaction shifted to the right side when:

Accepted Answer

A)   E0 = 0
B)   E0 > 0
C)   E0 < 0D) None of the above
E) All of the above B

Question 7

In an Ox/Red couple:

Accepted Answer

A)   The more positive reduction potential is the more oxidizing Ox is.
B)   The more positive reduction potential is the more reducing Red is.
C)   The more negative reduction potential is the more oxidizing Ox is.D) All of the above
E) B) and C)

Question 8

Which of the following half-reactions should be affected by the change in H+ concentration:
(i)  ClO2-(aq)  + H2O(l)  + 2e- → ClO-(aq)  + 2OH-(aq) 
(ii)  MnO2(s)  + 4H+(aq)  +2e- → Mn2+(aq)  + 2H2O(l) 
(iii)  ½ Cl2(aq)  + e- → Cl-(aq)

Accepted Answer

A)   (i)  and (iii) 
B)   (ii)  and (iii) 
C)   (i)  and (ii) D) None of the above
E) A) and B) C

Question 9

Which statement is correct in reference to the Frost diagrams?

Accepted Answer

A)   The maximum point on the diagram gives the most stable species with respect to the oxidation state zero which is set as a minimum point on the diagram.
B)   The minimum point on the diagram represents the most stable species with respect to the oxidation state zero which is set at 0 on the diagram.
C)   The maximum point on the diagram has the highest stability, and the lowest point, set at 0, corresponds to the least stable species.D) All of the above
E) B) and C)

Question 10

According to Ellingham diagram, the reduction of Al2O3 with carbon is feasible above 2400C, why is Al2O3 reduced in practice electrochemically rather than chemically with carbon?

Accepted Answer

A)   The temperature is too high and maintaining it is too expensive.
B)   It is difficult to achieve correct Al2O3-to-carbon ratio in practice.
C)   Formed Al is reducing enough to reduce CO and CO2 back to carbon.D) B) and C)
E) None of the above

Exam 6: Oxidation and Reduction

Find the correct statement:

Correct Answer
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Find the correct statement about Latimer diagrams and one of their uses:

Correct Answer
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Which statement is the correct one?

Correct Answer
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Find the correct statement(s) concerning the Pourbaix diagrams: (i) A horizontal line separates species related by proton transfer only (ii) A vertical line separates species related by electron transfer only (iii) Sloped lines separate species related by both electron and proton transfer.

Correct Answer
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Determine the oxidation states of sulfur in the following compounds (i) H₂S (ii) SO₂ and (iii) H₂SO₃.

Correct Answer
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C

A redox reaction shifted to the right side when:

Correct Answer
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B

In an Ox/Red couple:

Correct Answer
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Which of the following half-reactions should be affected by the change in H⁺ concentration: (i) ClO₂^-(aq) + H₂O(l) + 2e^- → ClO^-(aq) + 2OH^-(aq) (ii) MnO₂(s) + 4H⁺(aq) +2e^- → Mn²⁺(aq) + 2H₂O(l) (iii) ½ Cl₂(aq) + e^- → Cl^-(aq)

Correct Answer
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C

Which statement is correct in reference to the Frost diagrams?

Correct Answer
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According to Ellingham diagram, the reduction of Al₂O₃ with carbon is feasible above 2400C, why is Al₂O₃ reduced in practice electrochemically rather than chemically with carbon?

Correct Answer
verified

Exam 6: Oxidation and Reduction

Find the correct statement:

Correct AnswerverifiedShow Answer

Find the correct statement about Latimer diagrams and one of their uses:

Correct AnswerverifiedShow Answer

Which statement is the correct one?

Correct AnswerverifiedShow Answer

Find the correct statement(s) concerning the Pourbaix diagrams: (i) A horizontal line separates species related by proton transfer only (ii) A vertical line separates species related by electron transfer only (iii) Sloped lines separate species related by both electron and proton transfer.

Correct AnswerverifiedShow Answer

Determine the oxidation states of sulfur in the following compounds (i) H2S (ii) SO2 and (iii) H2SO3.

Correct AnswerverifiedC

A redox reaction shifted to the right side when:

Correct AnswerverifiedB

In an Ox/Red couple:

Correct AnswerverifiedShow Answer

Which of the following half-reactions should be affected by the change in H+ concentration: (i) ClO2-(aq) + H2O(l) + 2e- → ClO-(aq) + 2OH-(aq) (ii) MnO2(s) + 4H+(aq) +2e- → Mn2+(aq) + 2H2O(l) (iii) ½ Cl2(aq) + e- → Cl-(aq)

Correct AnswerverifiedC

Which statement is correct in reference to the Frost diagrams?

Correct AnswerverifiedShow Answer

According to Ellingham diagram, the reduction of Al2O3 with carbon is feasible above 2400C, why is Al2O3 reduced in practice electrochemically rather than chemically with carbon?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Determine the oxidation states of sulfur in the following compounds (i) H₂S (ii) SO₂ and (iii) H₂SO₃.

Correct Answer
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C

Correct Answer
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B

Correct Answer
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Which of the following half-reactions should be affected by the change in H⁺ concentration: (i) ClO₂^-(aq) + H₂O(l) + 2e^- → ClO^-(aq) + 2OH^-(aq) (ii) MnO₂(s) + 4H⁺(aq) +2e^- → Mn²⁺(aq) + 2H₂O(l) (iii) ½ Cl₂(aq) + e^- → Cl^-(aq)

Correct Answer
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C

Correct Answer
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According to Ellingham diagram, the reduction of Al₂O₃ with carbon is feasible above 2400C, why is Al₂O₃ reduced in practice electrochemically rather than chemically with carbon?

Correct Answer
verified