Electrolysis

Question 1

What does an electrolytic cell consist of

Answer 1

• Battery
• Electrodes
• Electrolyte

Question 2

Which is the positive electrode

Answer 2

Anode

Question 3

What are some weak electrolytes

Answer 3

• Weak acids and alkalis

Question 4

Which is the negative electrode

Answer 4

Cathode

Question 5

Define electrolysis

Answer 5

Electrolysis is the chemical decomposition of a compound by passing electricity through the compound when molten or aqueous

Question 6

Define an electrolyte

Answer 6

An electrolyte is a compound which when molten or aqueous, conducts electricity with its decomposition at the electrodes

Question 7

What reaction takes place at the cathode

Answer 7

Reduction

Question 8

What are some strong electrolytes

Answer 8

• Strong acids and alkalis
• Salt solutions

Question 9

What reaction takes place at the anode

Answer 9

Oxidation

Question 10

Define a binary compound

Answer 10

A binary compound is a compound containing only 2 elements

Question 11

Why are there OH- and H+ ions in aqueous solutions

Answer 11

Water undergoes reversible self-ionisation to produce a small concentration of OH- and H+ ions

Question 12

What are the factors affecting the discharge of ions during electrolysis

Answer 12

• Relative position of ions in electrochemical series
• Relative concentration of ions
• Nature of electrode

Question 13

Why will the ion that is lower in the electrochemical series be preferentially discharged

Answer 13

• Ion is less stable
• Ion gains electrons more easily to be discharged as a metal

Question 14

Which anions are usually not discharged

Answer 14

• F-
• SO42-
• NO3-

Question 15

Define electroplating

Answer 15

Electroplating is the coating of the surface of an object with a thin layer of a metal by electrolysis

Question 16

What is the equation for discharge of hydroxide ions

Answer 16

4OH-
–> 2H2O + O2 + 4e-

Question 17

In electrolysis, where is the object to be coated placed

Answer 17

Cathode

Question 18

What impurities are found in impure copper

Answer 18

Silver and gold

Question 19

How can the thickness of electroplating be adjusted

Answer 19

Adjusting:
- Magnitude of current
- Time duration of process

Question 20

What is a simple cell

Answer 20

A simple cell is a device that converts chemical energy to electrical energy

Question 21

Which is the negative electrode in a simple cell

Answer 21

More reactive metal

Question 22

How do electrons flow in a simple cell

Answer 22

From more reactive metal to less reactive metal

Question 23

Which is the positive electrode in a simple cell

Answer 23

Less reactive metal

Question 24

Where does reduction occur in a simple cell

Answer 24

Positive electrode

Question 25

How to increase voltage produced in a simple cell

Answer 25

Use metals for the electrodes that are far apart in the reactivity series

Question 26

When will the voltmeter read 0V in a simple cell

Answer 26

When electrodes are made of the same metal

Question 27

Define a fuel cell

Answer 27

A fuel cell is a chemical cell in which reactants are continuously supplied to produce electricity directly

Question 28

Where is the negative electrode in a fuel cell

Answer 28

Side where fuel enters

Question 29

Where is positive electrode in fuel cell

Answer 29

Side where oxygen enters

Question 30

How do electrons flow in a fuel cell

Answer 30

From negative to positive electrode