Module 3: Electrochemical Reactions

Question 1

Answer 1

Question 2

Answer 2

Question 3

Answer 3

Question 4

Answer 4

Question 5

Answer 5

Question 6

Answer 6

Question 7

Explain the difference between a reducing agent and an oxidizing agent using an example.

Answer 7

Reducing agent: substance that donates electrons and gets oxidized.
Oxidizing agent :substance that gains elections and gets reduced
Ex: When forming water hydrogen is the reducing agent, donating elections to oxygen which is the oxidizing agent

Question 8

Answer 8

Question 9

What is the redox spontaneity rule?

Answer 9

It states that a spontaneous redox reaction only occurs if the oxidizing agent is listed above the reducing agent in a redox table

Question 10

Answer 10

Question 11

Answer 11

Question 12

Answer 12

Question 13

Oxidation and reduction are processes, and oxidizing agents and reducing agents are substances. Explain this statement.

Answer 13

Oxidation and reduction refer to the process of electron transfer; oxidizing and reducing agents refer to species that gain or lose electrons in an electrochemical process.

Question 14

If a substance is a very strong oxidizing agent, what does this mean in terms of electrons?

Answer 14

Strong oxidizing agents have a strong affinity for electrons and promote the loss of electrons by other substances during a reaction.

Question 15

If a substance is a very strong reducing agent, what does this mean in terms of electrons?

Answer 15

Strong reducing agents have a weak affinity for electrons and tend to lose electrons to other substances during a reaction.

Question 16

Use the redox spontaneity rule to predict whether the following mixtures will show evidence of a reaction; that is, predict whether the reactions are spontaneous. (Do not write the equations for the reaction.)

a) nickel metal in a solution of silver ions
b) zinc metal in a solution of aluminum ions
c) an aqueous mixture of copper(II) ions and iodide ions
d) chlorine gas bubbled into a bromide ion solution
e) an aqueous mixture of copper(II) ions and tin(II) ions
f) copper metal in nitric acid

Answer 16

Use the redox spontaneity rule to predict whether the following mixtures will show evidence of a reaction; that is, predict whether the reactions are spontaneous. (Do not write the equations for the reaction.)

a) nickel metal in a solution of silver ions S
b) zinc metal in a solution of aluminum ions NS
c) an aqueous mixture of copper(II) ions and iodide ions. NS
d) chlorine gas bubbled into a bromide ion solution. S
e) an aqueous mixture of copper(II) ions and tin(II) ions S
f) copper metal in nitric acid S

Question 17

Five-Step Method for Predicting Redox Reactions

Answer 17

Step 1: List all entities present and classify each as a possible oxidizing agent, reducing agent, or both. Do not label spectator ions.
Step 2: Choose the strongest oxidizing agent as indicated in a redox table, and write the equation for its reduction.
Step 3: Choose the strongest reducing agent as indicated in the table, and write the equation for its oxidation.
Step 4: Balance the number of electrons lost and gained in the half-reaction equations by multiplying one or both equations by a number. Then add the two balanced half-reaction equations to obtain a net ionic equation.
Step 5: Using the spontaneity rule, predict whether the net ionic equation represents a spontaneous or non-spontaneous redox reaction.

Question 18

Complete the half-reaction equation and classify it as an
oxidation or a reduction.
dinitrogen oxide to nitrogen gas in an acidic solution

Answer 18

Question 19

complete the half-reaction equation and classify it as an
oxidation or a reduction.
nitrite ions to nitrate ions in a basic solution

Answer 19

Question 20

complete the half-reaction equation and classify it as an
oxidation or a reduction.
silver(I) oxide to silver metal in a basic solution

Answer 20

Question 21

complete the half-reaction equation and classify it as an
oxidation or a reduction.
nitrate ions to nitrous acid in an acidic solution

Answer 21

Question 22

complete the half-reaction equation and classify it as an
oxidation or a reduction.
hydrogen gas to water in a basic solution

Answer 22

Question 23

Answer 23

Question 24

Answer 24

Question 25

Answer 25

Question 26

Use the five-step method to predict the most likely redox reaction in each of the following situations. For any spontaneous reaction, describe one diagnostic test to identify a primary product. During a demonstration, zinc metal is placed in a hydrochloric acid solution.

Answer 26

Question 27

Use the five-step method to predict the most likely redox reaction in each of the following situations. For any spontaneous reaction, describe one diagnostic test to identify a primary product. A gold ring accidentally falls into a hydrochloric acid solution.

Answer 27

Question 28

Use the five-step method to predict the most likely redox reaction in each of the following situations. For any spontaneous reaction, describe one diagnostic test to identify a primary product. Nitric acid is painted onto a copper sheet to etch a design.

Answer 28

Question 29

Answer 29

Question 30

How do you balance a redox reaction in an acidic solution?

Answer 30

1. Assign oxidation numbers and identify atoms/ions with changes. 2. Calculate electrons transferred per atom. 3. Calculate total electrons transferred per reactant (use subscripts). 4. Balance electrons using whole number coefficients. 5. Balance oxygen using H₂O and hydrogen using H⁺

Question 31

How do you balance a redox reaction in a basic solution?

Answer 31

1. Assign oxidation numbers and identify atoms/ions with changes. 2. Calculate electrons transferred per atom. 3. Calculate total electrons transferred per reactant (use subscripts). 4. Balance electrons using whole number coefficients. 5. Balance oxygen using H₂O and hydrogen using H⁺ 6. Add OH⁻ equal to H⁺ on both sides. 7. Combine H⁺ and OH⁻ to form H₂O then cancel excess water.

Question 32

Determine the oxidation number

Answer 32

Question 33

Carbon can be progressively oxidized in a series of organic reactions. Determine the oxidation number of carbon in each of the compounds in the following series of oxidations:

Answer 33

Question 34

Assign oxidation numbers to the atoms/ions in each of the following by completing the table.

Answer 34

Question 35

Answer 35

Question 36

Draw a titration setup, labelling the following parts: burette, Erlenmeyer flask, sample, titrant

Answer 36

Question 37

What four assumptions must we make when performing a redox titration?

Answer 37

1. spontaneous 2. fast 3. stoichiometric 4. quantitative

Question 38

Explain what a standard solution is and why some substances have to be re-standardized as time progresses.

Answer 38

A standard solution is a solution where the concentration is accurately known. Some substances may continue to react as time progresses due to evaporation or temperature changes.

Question 39

Answer 39

Question 40

Answer 40

Question 41

Answer 41

B

Question 42

Answer 42

B

Question 43

Answer 43

1003

Question 44

Answer 44

B

Question 45

Answer 45

D

Question 46

Answer 46

A

Question 47

Answer 47

D

Question 48

Answer 48

B

Question 49

Answer 49

1984

Question 50

Answer 50

12.8

Question 51

Answer 51

8. A 9. D 10. B

Question 52

Answer 52

5876