A1 - Electrolysis of Sodium Chloride

Question 1

What is electrolysis?

Answer 1

The breakdown of a compound using electricity

Question 2

What is the term used to describe the breakdown of a compound using electricity?

Answer 2

Electrolysis

Question 3

Why do ionic substances have to be dissolved or molten during electrolysis?

Answer 3

So that the ions are free to move and carry a current

Question 4

What substances are produced in the electrolysis of molten NaCl?

Answer 4

Sodium (Na) and chlorine (Cl₂)

Question 5

What ions are present in the electrolysis of molten NaCl?

Answer 5

Na⁺ and Cl⁻

Question 6

What is produced at the positive anode in the electrolysis of molten NaCl?

Answer 6

Cl₂

Question 7

Where is Cl₂ produced in the electrolysis of molten NaCl?

Answer 7

The positive anode

Question 8

What is the equation for the formation of Cl₂ in the electrolysis of NaCl?

Answer 8

2Cl⁻ → Cl₂ + 2e⁻

Question 9

What is produced at the negative cathode in the electrolysis of molten NaCl?

Answer 9

Na

Question 10

Where is Na produced in the electrolysis of molten NaCl?

Answer 10

The negative cathode

Question 11

What is the equation for the formation of Na in the electrolysis of molten NaCl?

Answer 11

Na⁺ + e⁻ → Na

Question 12

What ions are present in the electrolysis of aqueous NaCl (brine)?

Answer 12

Na⁺, Cl⁻, H⁺, and OH⁻

Question 13

What is another name for aqueous NaCl?

Answer 13

Brine

Question 14

What is brine?

Answer 14

Aqueous NaCl

Question 15

What is produced at the negative cathode in the electrolysis of aqueous NaCl (brine)?

Answer 15

H₂

Question 16

Where is H₂ produced in the electrolysis of aqueous NaCl (brine)?

Answer 16

The negative cathode

Question 17

What is the equation for the formation of H₂ in the electrolysis of aqueous NaCl (brine)?

Answer 17

2H⁺ + 2e⁻ → H₂

Question 18

What is produced at the positive anode in the electrolysis of aqueous NaCl (brine)?

Answer 18

Cl₂

Question 19

Where is Cl₂ produced in the electrolysis of aqueous NaCl (brine)?

Answer 19

The positive anode

Question 20

What is left behind in solution in the electrolysis of aqueous NaCl (brine)?

Answer 20

NaOH

Question 21

Where is NaOH produced in the electrolysis of aqueous NaCl (brine)?

Answer 21

It is left behind in solution

Question 22

What is the purpose of using membrane or diaphragm in the electrolysis of aqueous NaCl (brine)?

Answer 22

To keep the Cl₂ and H₂ products separate as they form an explosive mixture

Question 23

What type of ions can pass through the diaphragm in the electrolysis of aqueous NaCl (brine)?

Answer 23

All ions can pass through the diaphragm

Question 24

Which separator allows all ions to pass through?

Answer 24

The diaphragm

Question 25

What is the disadvantage of using a diaphragm cell for the electrolysis of aqueous NaCl (brine)?

Answer 25

Some Cl⁻ ions pass through the diaphragm and contaminate the NaOH left in solution

Question 26

What type of ions can pass through the **membrane** in the electrolysis of aqueous NaCl (brine)?

Answer 26

Only positive ions can pass through the membrane

Question 27

Which separator only allows positive ions to pass through?

Answer 27

The membrane

Question 28

What is the advantage of using a membrane cell for the electrolysis of aqueous NaCl (brine)?

Answer 28

Cl⁻ ions **can't** pass through the diaphragm so the NaOH left in solution is uncontaminated