SC10 Electrolytic Processes

Question 1

Define cathode

Answer 1

A negative electrode

Question 2

Define anode

Answer 2

A positive electrode

Question 3

Define electrode

Answer 3

A rod of metal or graphite through which an electrical current flows in or out of an electrolyte

Question 4

Define electrolyte

Answer 4

Ionic compound in molten or dissolved solution that conducts the electricity

Question 5

Define electrolysis

Answer 5

The process in which energy, from a direct current supply, decomposes electrolytes

Question 6

What ions go towards the cathode?

Answer 6

Cations

Question 7

What ions go towards the anode?

Answer 7

Anions

Question 8

What direction do electrons move during electrolysis?

Answer 8

From the power supply to the cathode

Question 9

What occurs at the anode?

Answer 9

Negative ions lose their electrons

Question 10

What occurs at the cathode?

Answer 10

Electrons are transferred to the positive ions

Question 11

What ions will be present in the electrolysis of an aqueous solution?

Answer 11

• The ions of the electrolytes
• OH- ions
• H+ ions

Question 12

Why are OH- and H+ ions present in aqueous solutions?

Answer 12

Since aqueous substances are those dissolved in water, water will always be present. Those are the ions present in water

Question 13

What is produced at the cathode of the electrolysis of an aqueous solution?

Answer 13

Hydrogen (from H+ in water) is produced UNLESS the + ions in the ionic compound are from a metal that is less reactive than hydrogen. If the metal is less reactive, it will be produced instead

Question 14

What are the metals that are less reactive than hydrogen?

Answer 14

• copper
• silver
• gold
• platinum

Question 15

What is produced at the anode of the electrolysis of an aqueous solution?

Answer 15

Oxygen (from the OH-) and water UNLESS there is a group 7 ion present. If so, then it will be produced

Question 16

What are the ions present in a molten ionic solution?

Answer 16

The ions of the solution only

Question 17

What will be produced at the cathode of the electrolysis of a molten solution?

Answer 17

The + ions

Question 18

What will be produced at the anode of the electrolysis of a molten solution?

Answer 18

The - ions

Question 19

Why must the electrodes used be inert?

Answer 19

So they don’t participate with the reaction

Question 20

Define oxidation

Answer 20

The loss of electrons

Question 21

Define reduction

Answer 21

The gain of electrons

Question 22

Describe the half equation at the cathode

Answer 22

X+ - e- = X

Question 23

Where does reduction occur?

Answer 23

At the cathode

Question 24

Describe the half equation at the anode

Answer 24

X - = X + e-

Question 25

Where does oxidation occur?

Answer 25

At the anode

Question 26

What is the anode made of in the formation of copper through the electrolysis of copper sulfate?

Answer 26

Impure copper (that we're purifying)

Question 27

What is the cathode made of in the formation of copper through the electrolysis of copper sulfate?

Answer 27

Pure copper

Question 28

What happens in the formation of copper through the electrolysis of copper sulfate?

Answer 28

- Cu2+ ions from the anode move to the cathode, where they gain electrons and are discharged as pure copper - impurities form as sludge below the anode

Question 29

What change occurs in the anode during the electrolysis of copper sulfate?

Answer 29

It loses mass due to the loss of copper ions and impurities

Question 30

What change occurs in the anode during the electrolysis of copper sulfate?

Answer 30

It gains mass as it gains pure copper

Question 31

Is there a change in mass of the solution of copper sulfate during its electrolysis?

Answer 31

No, because the loss of mass in the anode is equivalent to the gain of mass of the cathode. Therefore, the concentration of copper ions remains constant

Question 32

Describe what is produced at the cathode and the anode during the electrolysis of copper chloride solution

Answer 32

Cathode: Copper Anode: Chlorine

Question 33

Describe what is produced at the cathode and the anode during the electrolysis of sodium chloride

Answer 33

Cathode: H+ Anode: Chlorine

Question 34

Describe what is produced at the cathode and the anode during the electrolysis of sodium sulfate

Answer 34

Cathode: H+ Anode: OH-

Question 35

Describe what is produced at the cathode and the anode during the electrolysis of aqueous sulfuric acid

Answer 35

Cathode: H+ Anode: OH-

Question 36

Describe what is produced at the cathode and the anode during the electrolysis of molten lead bromide

Answer 36

Cathode: Lead Anode: Bromine