Question 1

Balance the following reaction in KOH.What are the coefficients in front of C₉H₂₀O₂ and KMnO₄ in the balanced reaction? C₉H₂₀O₂(aq)+ KMnO₄(aq)→ C₉H₁₄O₄K₂(aq)+ MnO₂(aq)

Accepted Answer

The balanced reaction is: 3C₉H₂₀O₂(aq) + 8KMnO₄(aq) → 3C₉H₁₄O₄K₂(aq) + 8MnO₂(aq)

Question 2

What element is being oxidized in the following redox reaction? C₁₀H₂₂O₂(aq)+ KMnO₄(aq)→ C₁₀H₁₆O₄K₂(aq)+ MnO₂(aq)

Accepted Answer

In the reaction, carbon (C) in C2H5OH is oxidized as it goes from an oxidation state of -2 to +2, while manganese (Mn) in KMnO4 is reduced.

Question 3

What element is being oxidized in the following redox reaction? Mg²⁺(aq)+ NH₄⁺(aq)→ Mg(s)+ NO₃⁻(aq)

Accepted Answer

In the reaction, nitrogen (N) in NH₄⁺ is oxidized to NO₃⁻, as it increases its oxidation state from -3 in NH₄⁺ to +5 in NO₃⁻.

Question 4

What element is being reduced in the following redox reaction? C₃H₈O₂(aq)+ KMnO₄(aq)→ C₃H₂O₄K₂(aq)+ MnO₂(aq)

Accepted Answer

In the given redox reaction, Mn is being reduced as it goes from a higher oxidation state in KMnO4 to a lower oxidation state in MnO2. Reduction involves a decrease in oxidation state.

Question 5

A sacrificial electrode is composed of a metal that

Accepted Answer

A sacrificial electrode is a method of corrosion protection where a more easily corroded metal is connected to the metal being protected. This more easily corroded metal, known as the sacrificial electrode, will corrode preferentially to the protected metal, thereby slowing its corrosion. The sacrificial electrode must oxidize more easily than the protected metal for this method to be effective, so option D is the correct answer.

Question 6

Aluminum is quickly oxidized in the air to form

Accepted Answer

Aluminum reacts with oxygen in the air to form aluminum oxide, Al₂O₃, which creates a protective layer preventing further oxidation.

Question 7

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Na⁺,Ca²⁺,Cl⁻,Br⁻,F⁻

Accepted Answer

The species with the lowest reduction potential will be reduced first. From the given species, NaS1U1P1 has the lowest reduction potential due to the highly electropositive nature of sodium. Therefore, NaS1U1P1+S1S1P0 is the most likely species to be reduced first.

Question 8

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Zn²⁺,Fe³⁺,Mg²⁺,Br^-,I^-

Accepted Answer

The answer of Predict the species that will be reduced...

Question 9

Identify a component in the formation of rust.

Accepted Answer

Rust formation typically involves the presence of moisture (water), and can be accelerated by the presence of salt and acids, which increase the conductivity of the water, facilitating the electrochemical process of rusting.

Question 10

Define extraction.

Accepted Answer

Extraction refers to the process of obtaining a metal from its ore through reduction or oxidation. Choice E describes the extraction process where free metal is reduced out of its ore.

Question 11

Identify oxidation.

Accepted Answer

Oxidation involves the loss of electrons and an increase in oxidation number. Therefore, options A and B are both correct and the best choice is E. Options C and D are not related to oxidation.

Question 12

Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of Crand Cl₂ in the balanced reaction? Cr(s)+ Cl₂(g)→ Cr³⁺(aq)+ Cl^-(aq)

Accepted Answer

In a basic solution, the half-reaction for the oxidation of Cr is:Cr(s) → Cr(OH)3(aq) + 3e-The half-reaction for the reduction of Cl2 is:Cl2(g) + 2e- → 2Cl-(aq)To balance the number of electrons lost and gained, we multiply the first half-reaction by 2 and the second half-reaction by 3:2Cr(s) → 2Cr(OH)3(aq) + 6e-3Cl2(g) + 6e- → 6Cl-(aq)Adding the two half-reactions, we get the overall balanced reaction:2Cr(s) + 3Cl2(g) → 2Cr(OH)3(aq) + 6Cl-(aq)

Question 13

Predict the species that will be oxidized first if the following mixture of molten salts undergoes electrolysis. Cu²⁺,Mg²⁺,Cl⁻,Br⁻,F⁻

Accepted Answer

In electrolysis, the species with the lowest oxidation potential will be oxidized first. Among the given anions, Br⁻ has the lowest oxidation potential compared to Cl⁻ and F⁻, making it the species that will be oxidized first.

Question 14

Balance the following redox reaction if it occurs in H₂SO₄.What are the coefficients in front of C₁₀H₂₂O₂and H₂SO₄ in the balanced reaction? C₁₀H₂₂O₂(aq)+ Na₂Cr₂O₇(aq)→ C₁₀H₁₈O₄(aq)+ Cr₂(SO₄)₃(aq)

Accepted Answer

To balance the redox reaction, we need to first identify the oxidation state of each element in the reaction. In this case, we have: Cr: +6 to +3 O: -2 to 0 S: +6 to -2 C: +4 to +3 H: +1 to 0 Na: +1 to +2 To balance the reaction, we begin by balancing the number of atoms of each element. Then we must balance the charges with electrons. Finally, we add the two half-reactions together and cancel out any terms that appear on both sides of the equation. The balanced equation is: 3 C₁₀H₂₂O₂(aq) + 8 Na₂Cr₂O₇(aq) → 3 C₁₀H₁₈O₄(aq) + 2 Cr(SO₄)₃(aq) Therefore, the coefficients in front of C₁₀H₂₂O₂ and H₂SO₄ are 3 and 16, respectively. The best choice is D because it is the only option with the correct coefficients for both of these species.

Question 15

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Fe and Ag⁺ in the balanced reaction? Fe(s)+ Ag⁺(aq)→ Ag(s)+ Fe²⁺(aq)

Accepted Answer

The balanced redox reaction in acidic solution is Fe(s) + 2Ag⁺(aq) → 2Ag(s) + Fe²⁺(aq), so the coefficients in front of Fe and Ag⁺ are 1 and 2, respectively.

Question 16

Define corrosion.

Accepted Answer

Corrosion is the undesired oxidation of metals from oxidizing agents in the environment, which leads to the deterioration of the metal's surface or structure. This can include processes such as rusting in iron or steel, tarnishing in silver, or pitting in aluminum.

Question 17

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Pb and HS1U1P1+S1S1P0 in the balanced reaction? 
PbS1U1P12+S1S1P0(aq)+ NHS1U1B14S1U1B0S1U1P1+S1S1P0(aq)? Pb(s)+ NOS1U1B13S1U1B0?(aq)

Accepted Answer

The balanced equation is: 
PbS1U1P12 + 8HS1U1B14S1U1B0 + 5NOS1U1B13S1U1B0⁻ → Pb + 5NOS1U1B13S1U1B0⁻ + 4HS1U1P1 + S1S1P0 
To balance the equation, the first step is to assign oxidation states: 
Pb in PbS1U1P12 → Pb in Pb: 0 (elemental form) 
S in PbS1U1P12 → S in S1U1B0: -2 
P in PbS1U1P12 → P in S1U1P1: +5 
S in S1S1P0 → S in S1U1B0: -2 
P in S1S1P0 → P in S1U1P1: +5 
N in NOS1U1B13S1U1B0⁻ → N in NO: +2 
S in NOS1U1B13S1U1B0⁻ → S in S1U1B0: -2 
B in NHS1U1B14S1U1B0 → B in S1U1B0⁻: +3 
H in NHS1U1B14S1U1B0 → H in HS1U1P1: +1 
Next, balance the number of atoms of each element, starting with elements that occur only once on each side of the equation: 
PbS1U1P12 + 8HS1U1B14S1U1B0 + 5NOS1U1B13S1U1B0⁻ → Pb + 5NOS1U1B13S1U1B0⁻ + 4HS1U1P1 + S1S1P0 
1 Pb: 1 Pb 
2 P: 1 PbS1U1P12, 1S1U1P1 
2 P: 1S1S1P0, 5NOS1U1B13S1U1B0⁻ 
10 H: 8HS1U1B14S1U1B0, 4HS1U1P1 
4 S: 1 PbS1U1P12, 1S1S1P0, 5NOS1U1B13S1U1B0⁻, 8HS1U1B14S1U1B0, 1S1U1B0⁻ 
Finally, balance the charges by adding electrons: 
PbS1U1P12 + 8HS1U1B14S1U1B0 + 5NOS1U1B13S1U1B0⁻ → Pb + 5NOS1U1B13S1U1B0⁻ + 4HS1U1P1 + S1S1P0 + 12e- 
Balance the half-reactions: 
Oxidation: PbS1U1P12 → Pb + 2e- (multiply by 2) 
Reduction: 8H⁺ + 5NO3⁻ + 12e- → 5NO + 4H2O (multiply by 3) 
The final balanced equation is: 
2PbS1U1P12 + 16HS1U1B14S1U1B0 + 15NOS1U1B13S1U1B0⁻ → 2Pb + 25NO + 8HS1U1P1 + 2S1S1P0 + 16H2O 
Therefore, the coefficients in front of Pb, S1U1B0⁻, and HS1U1P1 are Pb = 4, S1U1B0⁻ = 10, and HS1U1P1 = 8. The best choice is C.

Question 18

To prevent rust,nails are coated with

Accepted Answer

Zinc is commonly used as a coating on nails to prevent rust because it is a sacrificial metal, which means that it will corrode instead of the iron in the nail, protecting it from rust. Salt, calcium, sodium, and lithium are not effective coatings for preventing rust on nails.

Question 19

Balance the following redox reaction if it occurs in H₂SO₄.What are the coefficients in front of H₂O and Cr₂(SO₄)₃ in the balanced reaction? C₇H₁₆O₂(aq)+ Na₂Cr₂O₇(aq)→ C₇H₁₂O₄(aq)+ Cr₂(SO₄)₃(aq)

Accepted Answer

The answer of Balance the following redox reaction if it...

Question 20

Describe the reactions during the electrolysis of water.

Accepted Answer

During electrolysis of water, oxygen is produced at the anode by oxidation and hydrogen is produced at the cathode by reduction. Therefore, oxygen is oxidized and hydrogen is reduced. So, the best choice is D – Oxygen is oxidized and hydrogen is reduced.

Quiz 19: Electrochemistry

Balance the following reaction in KOH.What are the coefficients in front of C₉H₂₀O₂ and KMnO₄ in the balanced reaction? C₉H₂₀O₂(aq) + KMnO₄(aq) → C₉H₁₄O₄K₂(aq) + MnO₂(aq)

What element is being oxidized in the following redox reaction? C₁₀H₂₂O₂(aq) + KMnO₄(aq) → C₁₀H₁₆O₄K₂(aq) + MnO₂(aq)

What element is being oxidized in the following redox reaction? Mg²⁺(aq) + NH₄⁺(aq) → Mg(s) + NO₃⁻(aq)

What element is being reduced in the following redox reaction? C₃H₈O₂(aq) + KMnO₄(aq) → C₃H₂O₄K₂(aq) + MnO₂(aq)

A sacrificial electrode is composed of a metal that

Aluminum is quickly oxidized in the air to form

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Na⁺,Ca²⁺,Cl⁻,Br⁻,F⁻

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Zn²⁺,Fe³⁺,Mg²⁺,Br^-,I^-

Identify a component in the formation of rust.

Define extraction.

Identify oxidation.

Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of Crand Cl₂ in the balanced reaction? Cr(s) + Cl₂(g) → Cr³⁺(aq) + Cl^-(aq)

Predict the species that will be oxidized first if the following mixture of molten salts undergoes electrolysis. Cu²⁺,Mg²⁺,Cl⁻,Br⁻,F⁻

Balance the following redox reaction if it occurs in H₂SO₄.What are the coefficients in front of C₁₀H₂₂O₂and H₂SO₄ in the balanced reaction? C₁₀H₂₂O₂(aq) + Na₂Cr₂O₇(aq) → C₁₀H₁₈O₄(aq) + Cr₂(SO₄) ₃(aq)

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Fe and Ag⁺ in the balanced reaction? Fe(s) + Ag⁺(aq) → Ag(s) + Fe²⁺(aq)

Define corrosion.

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Pb and H⁺ in the balanced reaction? Pb²⁺(aq) + NH₄⁺(aq) ? Pb(s) + NO₃?(aq)

To prevent rust,nails are coated with

Balance the following redox reaction if it occurs in H₂SO₄.What are the coefficients in front of H₂O and Cr₂(SO₄) ₃ in the balanced reaction? C₇H₁₆O₂(aq) + Na₂Cr₂O₇(aq) → C₇H₁₂O₄(aq) + Cr₂(SO₄) ₃(aq)

Describe the reactions during the electrolysis of water.

Quiz 19: Electrochemistry

Balance the following reaction in KOH.What are the coefficients in front of C9H20O2 and KMnO4 in the balanced reaction? C9H20O2(aq) + KMnO4(aq) → C9H14O4K2(aq) + MnO2(aq)

What element is being oxidized in the following redox reaction? C10H22O2(aq) + KMnO4(aq) → C10H16O4K2(aq) + MnO2(aq)

What element is being oxidized in the following redox reaction? Mg2+(aq) + NH4+(aq) → Mg(s) + NO3⁻(aq)

What element is being reduced in the following redox reaction? C3H8O2(aq) + KMnO4(aq) → C3H2O4K2(aq) + MnO2(aq)

A sacrificial electrode is composed of a metal that

Aluminum is quickly oxidized in the air to form

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Na+,Ca2+,Cl⁻,Br⁻,F⁻

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Zn2+,Fe3+,Mg2+,Br-,I-

Identify a component in the formation of rust.

Define extraction.

Identify oxidation.

Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of Cr and Cl2 in the balanced reaction? Cr(s) + Cl2(g) → Cr3+(aq) + Cl-(aq)

Predict the species that will be oxidized first if the following mixture of molten salts undergoes electrolysis. Cu2+,Mg2+,Cl⁻,Br⁻,F⁻

Balance the following redox reaction if it occurs in H2SO4.What are the coefficients in front of C10H22O2 and H2SO4 in the balanced reaction? C10H22O2(aq) + Na2Cr2O7(aq) → C10H18O4(aq) + Cr2(SO4) 3(aq)

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Fe and Ag+ in the balanced reaction? Fe(s) + Ag+(aq) → Ag(s) + Fe2+(aq)

Define corrosion.

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Pb and H+ in the balanced reaction? Pb2+(aq) + NH4+(aq) ? Pb(s) + NO3?(aq)

To prevent rust,nails are coated with

Balance the following redox reaction if it occurs in H2SO4.What are the coefficients in front of H2O and Cr2(SO4) 3 in the balanced reaction? C7H16O2(aq) + Na2Cr2O7(aq) → C7H12O4(aq) + Cr2(SO4) 3(aq)

Describe the reactions during the electrolysis of water.

Balance the following reaction in KOH.What are the coefficients in front of C₉H₂₀O₂ and KMnO₄ in the balanced reaction? C₉H₂₀O₂(aq) + KMnO₄(aq) → C₉H₁₄O₄K₂(aq) + MnO₂(aq)

What element is being oxidized in the following redox reaction? C₁₀H₂₂O₂(aq) + KMnO₄(aq) → C₁₀H₁₆O₄K₂(aq) + MnO₂(aq)

What element is being oxidized in the following redox reaction? Mg²⁺(aq) + NH₄⁺(aq) → Mg(s) + NO₃⁻(aq)

What element is being reduced in the following redox reaction? C₃H₈O₂(aq) + KMnO₄(aq) → C₃H₂O₄K₂(aq) + MnO₂(aq)

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Na⁺,Ca²⁺,Cl⁻,Br⁻,F⁻

Predict the species that will be reduced first if the following mixture of molten salts undergoes electrolysis. Zn²⁺,Fe³⁺,Mg²⁺,Br^-,I^-

Balance the following redox reaction if it occurs in basic solution.What are the coefficients in front of Crand Cl₂ in the balanced reaction? Cr(s) + Cl₂(g) → Cr³⁺(aq) + Cl^-(aq)

Predict the species that will be oxidized first if the following mixture of molten salts undergoes electrolysis. Cu²⁺,Mg²⁺,Cl⁻,Br⁻,F⁻

Balance the following redox reaction if it occurs in H₂SO₄.What are the coefficients in front of C₁₀H₂₂O₂and H₂SO₄ in the balanced reaction? C₁₀H₂₂O₂(aq) + Na₂Cr₂O₇(aq) → C₁₀H₁₈O₄(aq) + Cr₂(SO₄) ₃(aq)

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Fe and Ag⁺ in the balanced reaction? Fe(s) + Ag⁺(aq) → Ag(s) + Fe²⁺(aq)

Balance the following redox reaction if it occurs in acidic solution.What are the coefficients in front of Pb and H⁺ in the balanced reaction? Pb²⁺(aq) + NH₄⁺(aq) ? Pb(s) + NO₃?(aq)

Balance the following redox reaction if it occurs in H₂SO₄.What are the coefficients in front of H₂O and Cr₂(SO₄) ₃ in the balanced reaction? C₇H₁₆O₂(aq) + Na₂Cr₂O₇(aq) → C₇H₁₂O₄(aq) + Cr₂(SO₄) ₃(aq)