Question 1

The equilibrium constant at 25 ^oC for the following reaction is 2 x 10^-3. H₂(g) + 2Ru³⁺(aq) $\rightarrow$ 2 H⁺(aq) + 2Ru²⁺(aq) What is the value of E° for the reaction?

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Question 2

Calculate the value of the K_sp for CdS at 25 °C from the following data. CdS + 2 e^- Cd + S^2- E° = -1.21 V Cd²⁺ + 2 e^- Cd E° = -0.40 V

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Question 3

There are two half-reactions for the reduction of O₂ to H₂O. Use these half-reactions to calculate the ionization constant for water, K_w, at 25 °C. H₂O(l) H⁺(aq) + OH^-(aq) K_w = ?

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Question 4

The half-reaction reduction potentials for the mercury(I) and silver(I) ions are given below.

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Question 5

Calculate the complex dissociation equilibrium constant (K_d) for the Cd(NH₃)₄²⁺ complex from the following data at 298K.

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Question 6

Calculate the weight of sodium metal that would be produced by the electrolysis of molten sodium chloride for 1.00 hour with a 10.0-amp current.

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Question 7

What is the ratio of the weight of Cl₂ produced at the anode to the weight of Al produced at the cathode when 5 moles of electrons are passed through a molten sample of AlCl₃?

Accepted Answer

The ratio of the weight of Cl₂ produced at the anode to the weight of Al produced at the cathode is equal to the ratio of their molar masses. The molar mass of Cl₂ is 70.9 g/mol, and the molar mass of Al is 26.98 g/mol. Therefore, the ratio of the weight of Cl₂ produced to the weight of Al produced is 70.9 g/mol / 26.98 g/mol = 2.63. This means that for every 1 g of Al produced, 2.63 g of Cl₂ is produced. The closest answer choice to this value is B) about 4 g Cl₂ per 1 g Al.

Question 8

Calculate the amount of aluminum produced in 1.00 hour by the electrolysis of molten AlCl₃ if the current is 10.0 A.

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Question 9

Suppose a beer can weighs 40.0 g. Determine the amount of time in hours that a current of 100.0 amp need to be passed through a molten AlF₃ electrolysis cell to produce enough Al to replace a discarded beer can. Sketch the electrolysis cell, labeling the electrodes and showing the direction of electron flow in the external circuit as part of your answer.

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Question 10

Which of the following electrolysis processes will produce the largest volume of Cl₂ gas at STP?

Accepted Answer

Passing 2 moles of electrons through a CaCl2 solution will produce 1 mole of Cl2 gas, which is the largest volume compared to the other options.

Question 11

A current of 1.5 amps is applied to a 1.00 L solution of 0.100 M hydrochloric acid for 1.0 hr. What is the pH of the solution after electrolysis is complete?

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Question 12

A molten sample of TiCl₄ was electrolyzed for 10.0 hours at 12 amps. What is the ratio of the weight of Cl₂ produced compared to that of Ti?

Accepted Answer

The electrolysis of TiCl4 produces Ti and Cl2. The molar mass of Ti is 47.87 g/mol and Cl2 is 70.90 g/mol. The reaction involves 4 moles of electrons per mole of Ti and 2 moles of electrons per mole of Cl2. Using Faraday's laws, calculate the moles of Ti and Cl2 produced, then find the mass ratio.

Question 13

An electric current is passed through a solution of CuSO₄(aq) producing Cu(s) at the cathode and O₂(g) at the anode. If 3.48 L of O₂(g) measured at STP is produced at the anode, how many grams of Cu(s) must have been deposited on the cathode?

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Question 14

What is the ratio by weight of Br₂ to Cr if a molten sample of CrBr₂ is electrolyzed for 4.00 hr. at 10.0 amps?

Accepted Answer

The electrolysis of CrBr₂ involves the reduction of Cr²⁺ to Cr and the oxidation of Br^- to Br₂. The molar mass of Cr is 52 g/mol and Br₂ is 160 g/mol. The ratio by weight of Br₂ to Cr is calculated based on the stoichiometry of the reaction and the molar masses, resulting in approximately 3.07 g Br₂ per 1 g Cr.

Question 15

How much Cl₂ gas would be collected when a 2.00 M NaCl(aq) solution is electrolyzed for 2.00 hours with a current of 15.0 amps?

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Question 16

A current of 10.0 amps over a period of 3.00 hr is passed through a solution of molten KCl. What weight of K metal is produced?

Accepted Answer

The weight of K metal produced can be calculated using Faraday's laws of electrolysis. The charge passed is 10.0 A * 3.00 hr * 3600 s/hr = 108,000 C. The molar mass of K is 39.1 g/mol, and it requires 1 mole of electrons (96,485 C) to produce 1 mole of K. Therefore, the weight of K produced is (108,000 C / 96,485 C/mol) * 39.1 g/mol = 43.8 g.

Question 17

A current of 2.0 amps passed through a molten solution of the salt MCl₂ for a period of 30 minutes produces 1.32 g of Cl₂ gas and 0.453 g of M. Which of the following metals is present in this compound?

Accepted Answer

The correct answer is A because the molar mass of Cl₂ is 70.9 g/mol, and the molar mass of M is 45.3 g/mol. The number of moles of Cl₂ produced is 1.32 g / 70.9 g/mol = 0.0186 mol. The number of moles of M produced is 0.453 g / 45.3 g/mol = 0.01 mol. The ratio of moles of Cl₂ to moles of M is 0.0186 mol / 0.01 mol = 1.86. This ratio is closest to the ratio of 2:1, which is the ratio of moles of Cl₂ to moles of M in MgCl₂.

Question 18

What is the oxidation state of the osmium atom in an unknown salt if 26.7 grams of osmium plate out when a current of 15.0 amps is passed through a solution of this salt for 1.00 hour?

Accepted Answer

The mass of osmium plated out can be used to calculate the moles of electrons transferred. Using Faraday's laws of electrolysis, the charge passed is 15.0 A * 3600 s = 54000 C. The moles of electrons is 54000 C / 96485 C/mol = 0.56 mol. The moles of osmium is 26.7 g / 190.23 g/mol = 0.14 mol. The ratio of moles of electrons to moles of osmium is 0.56/0.14 = 4, indicating an oxidation state of +4.

Question 19

What is the oxidation state of the cerium atom in Ce_xZ_y if a current of 1.2 amps for 3.0 hours deposits 4.70 g of Ce at the cathode?

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Question 20

What is the oxidation state of the tin atom in an unknown salt if 14.8 grams of tin are plated out when a current of 40 amps is passed through a molten solution of this salt for 10 minutes?

Accepted Answer

The amount of tin plated out can be used to calculate the moles of electrons transferred. Using Faraday's laws of electrolysis, the oxidation state of tin is determined to be +2.

Quiz 12: Oxidation-Reduction Reactions

The equilibrium constant at 25 ^oC for the following reaction is 2 x 10^-3. H₂(g) + 2Ru³⁺(aq) $\rightarrow$ 2 H⁺(aq) + 2Ru²⁺(aq) What is the value of E° for the reaction?

Calculate the value of the K_sp for CdS at 25 °C from the following data. CdS + 2 e^- Cd + S^2- E° = -1.21 V Cd²⁺ + 2 e^- Cd E° = -0.40 V

There are two half-reactions for the reduction of O₂ to H₂O. Use these half-reactions to calculate the ionization constant for water, K_w, at 25 °C. H₂O(l) H⁺(aq) + OH^-(aq) K_w = ?

The half-reaction reduction potentials for the mercury(I) and silver(I) ions are given below.

Calculate the complex dissociation equilibrium constant (K_d) for the Cd(NH₃) ₄²⁺ complex from the following data at 298K.

Calculate the weight of sodium metal that would be produced by the electrolysis of molten sodium chloride for 1.00 hour with a 10.0-amp current.

What is the ratio of the weight of Cl₂ produced at the anode to the weight of Al produced at the cathode when 5 moles of electrons are passed through a molten sample of AlCl₃?

Calculate the amount of aluminum produced in 1.00 hour by the electrolysis of molten AlCl₃ if the current is 10.0 A.

Which of the following electrolysis processes will produce the largest volume of Cl₂ gas at STP?

A current of 1.5 amps is applied to a 1.00 L solution of 0.100 M hydrochloric acid for 1.0 hr. What is the pH of the solution after electrolysis is complete?

A molten sample of TiCl₄ was electrolyzed for 10.0 hours at 12 amps. What is the ratio of the weight of Cl₂ produced compared to that of Ti?

An electric current is passed through a solution of CuSO₄(aq) producing Cu(s) at the cathode and O₂(g) at the anode. If 3.48 L of O₂(g) measured at STP is produced at the anode, how many grams of Cu(s) must have been deposited on the cathode?

What is the ratio by weight of Br₂ to Cr if a molten sample of CrBr₂ is electrolyzed for 4.00 hr. at 10.0 amps?

How much Cl₂ gas would be collected when a 2.00 M NaCl(aq) solution is electrolyzed for 2.00 hours with a current of 15.0 amps?

A current of 10.0 amps over a period of 3.00 hr is passed through a solution of molten KCl. What weight of K metal is produced?

A current of 2.0 amps passed through a molten solution of the salt MCl₂ for a period of 30 minutes produces 1.32 g of Cl₂ gas and 0.453 g of M. Which of the following metals is present in this compound?

What is the oxidation state of the osmium atom in an unknown salt if 26.7 grams of osmium plate out when a current of 15.0 amps is passed through a solution of this salt for 1.00 hour?

What is the oxidation state of the cerium atom in Ce_xZ_y if a current of 1.2 amps for 3.0 hours deposits 4.70 g of Ce at the cathode?

What is the oxidation state of the tin atom in an unknown salt if 14.8 grams of tin are plated out when a current of 40 amps is passed through a molten solution of this salt for 10 minutes?

Quiz 12: Oxidation-Reduction Reactions

The equilibrium constant at 25 oC for the following reaction is 2 x 10-3. H2(g) + 2Ru3+(aq) →\rightarrow→ 2 H+(aq) + 2Ru2+(aq) What is the value of E° for the reaction?

Calculate the value of the Ksp for CdS at 25 °C from the following data. CdS + 2 e- Cd + S2- E° = -1.21 V Cd2+ + 2 e- Cd E° = -0.40 V

There are two half-reactions for the reduction of O2 to H2O. Use these half-reactions to calculate the ionization constant for water, Kw, at 25 °C. H2O(l) H+(aq) + OH-(aq) Kw = ?

The half-reaction reduction potentials for the mercury(I) and silver(I) ions are given below.

Calculate the complex dissociation equilibrium constant (Kd) for the Cd(NH3) 42+ complex from the following data at 298K.

Calculate the weight of sodium metal that would be produced by the electrolysis of molten sodium chloride for 1.00 hour with a 10.0-amp current.

What is the ratio of the weight of Cl2 produced at the anode to the weight of Al produced at the cathode when 5 moles of electrons are passed through a molten sample of AlCl3?

Calculate the amount of aluminum produced in 1.00 hour by the electrolysis of molten AlCl3 if the current is 10.0 A.

Which of the following electrolysis processes will produce the largest volume of Cl2 gas at STP?

A current of 1.5 amps is applied to a 1.00 L solution of 0.100 M hydrochloric acid for 1.0 hr. What is the pH of the solution after electrolysis is complete?

A molten sample of TiCl4 was electrolyzed for 10.0 hours at 12 amps. What is the ratio of the weight of Cl2 produced compared to that of Ti?

An electric current is passed through a solution of CuSO4(aq) producing Cu(s) at the cathode and O2(g) at the anode. If 3.48 L of O2(g) measured at STP is produced at the anode, how many grams of Cu(s) must have been deposited on the cathode?

What is the ratio by weight of Br2 to Cr if a molten sample of CrBr2 is electrolyzed for 4.00 hr. at 10.0 amps?

How much Cl2 gas would be collected when a 2.00 M NaCl(aq) solution is electrolyzed for 2.00 hours with a current of 15.0 amps?

A current of 10.0 amps over a period of 3.00 hr is passed through a solution of molten KCl. What weight of K metal is produced?

A current of 2.0 amps passed through a molten solution of the salt MCl2 for a period of 30 minutes produces 1.32 g of Cl2 gas and 0.453 g of M. Which of the following metals is present in this compound?

What is the oxidation state of the osmium atom in an unknown salt if 26.7 grams of osmium plate out when a current of 15.0 amps is passed through a solution of this salt for 1.00 hour?

What is the oxidation state of the cerium atom in CexZy if a current of 1.2 amps for 3.0 hours deposits 4.70 g of Ce at the cathode?

What is the oxidation state of the tin atom in an unknown salt if 14.8 grams of tin are plated out when a current of 40 amps is passed through a molten solution of this salt for 10 minutes?

The equilibrium constant at 25 ^oC for the following reaction is 2 x 10^-3. H₂(g) + 2Ru³⁺(aq) $\rightarrow$ 2 H⁺(aq) + 2Ru²⁺(aq) What is the value of E° for the reaction?

Calculate the value of the K_sp for CdS at 25 °C from the following data. CdS + 2 e^- Cd + S^2- E° = -1.21 V Cd²⁺ + 2 e^- Cd E° = -0.40 V

There are two half-reactions for the reduction of O₂ to H₂O. Use these half-reactions to calculate the ionization constant for water, K_w, at 25 °C. H₂O(l) H⁺(aq) + OH^-(aq) K_w = ?

Calculate the complex dissociation equilibrium constant (K_d) for the Cd(NH₃) ₄²⁺ complex from the following data at 298K.

What is the ratio of the weight of Cl₂ produced at the anode to the weight of Al produced at the cathode when 5 moles of electrons are passed through a molten sample of AlCl₃?

Calculate the amount of aluminum produced in 1.00 hour by the electrolysis of molten AlCl₃ if the current is 10.0 A.

Which of the following electrolysis processes will produce the largest volume of Cl₂ gas at STP?

A molten sample of TiCl₄ was electrolyzed for 10.0 hours at 12 amps. What is the ratio of the weight of Cl₂ produced compared to that of Ti?

An electric current is passed through a solution of CuSO₄(aq) producing Cu(s) at the cathode and O₂(g) at the anode. If 3.48 L of O₂(g) measured at STP is produced at the anode, how many grams of Cu(s) must have been deposited on the cathode?

What is the ratio by weight of Br₂ to Cr if a molten sample of CrBr₂ is electrolyzed for 4.00 hr. at 10.0 amps?

How much Cl₂ gas would be collected when a 2.00 M NaCl(aq) solution is electrolyzed for 2.00 hours with a current of 15.0 amps?

A current of 2.0 amps passed through a molten solution of the salt MCl₂ for a period of 30 minutes produces 1.32 g of Cl₂ gas and 0.453 g of M. Which of the following metals is present in this compound?

What is the oxidation state of the cerium atom in Ce_xZ_y if a current of 1.2 amps for 3.0 hours deposits 4.70 g of Ce at the cathode?