5.5.1- Molten Electrolysis

Question 1

What is electrolysis !?

Answer 1

Electrolysis**is the **breaking down** of a compound, **using electricity

(The substance to be broken down is connected into a circuit with a cell or battery)

Question 2

Label:

Answer 2

Question 3

What is the role of the electrodes !?

Answer 3

There are two electrodes, which connect the substance into the circuit

Question 4

What is the positive (+) electrode called !?

Answer 4

The positive electrode is called the anode

Question 5

What is the negative (-) electrode called !?

Answer 5

The negative electrode is called the cathode

Question 6

What material must the electrode be made out of?

Answer 6

The electrodes must be made from a solid that conducts electricity, but is inert

Question 7

Definition of inert:

Answer 7

Unreactive

Question 8

What are electrodes usually made out of !?

Answer 8

Usually one of graphite (cheap) or platinum (expensive) are used

Question 9

What is the electrolyte !?

Answer 9

The electrolyte is the substance to be broken down, and it needs to conduct electricity

Question 10

What are the only compounds that conduct electricity !?

Answer 10

The only compounds that conduct electricity are ionic compounds that are molten or dissolved, so the ions are free to move

Question 11

Why won’t solid ionic compounds work within molten electrolysis?

Answer 11

Solid ionic compounds won’t work because the ions can’t move

Question 12

Why won’t covalent compounds work within molten electrolysis?

Answer 12

covalent compounds won’t work because the molecules aren’t even charged

Question 13

What are cations !?

Answer 13

Positive ions are called cations because they are attracted to the cathode

Question 14

What are anions !?

Answer 14

The negative ions are called anions because they’re attracted to the anode

Question 15

What does the electrolysis of a molten ionic compound produce !?

Answer 15

Electrolysis of a molten ionic compound produces its elements

COMPOUND ➡️ ELEMENTS

Question 16

What are the two-halves of electrolysis!?

Answer 16

The anode half
and
the cathode half

Question 17

What happens at the anode half in the electrolysis of molten magnesium chloride!?

Answer 17

The Cl- ions are attracted to the anode and they lose electrons to form neutral Cl atoms.

Question 18

How many electrons do the Cl ions lose at the anode to become neutral during the molten electrolysis of magnesium chloride?

Answer 18

as each Cl ion has a 1- charge. They lose one electron each to become neutral.

Question 19

Why do Cl2 molecules form at the anode during the molten electrolysis of magnesium chloride!?

Answer 19

Nonmetals are made up of diatomic molecules so the Cl atoms pair up to form Cl2 molecules.

Question 20

What happens at the anode during molten electrolysis!?

Answer 20

Nonmetal ions lose electrons to form molecules

Question 21

What is the half equation of Cl at the anode during the molten electrolysis of magnesium chloride!?

Answer 21

We write this as a half equation, showing the Cl- ions, losing electrons and becoming molecules.

Question 22

Have the Cl- ions been oxidised or reduced during the molten electrolysis of magnesium chloride!?

Answer 22

The Cl- ions have been oxidised because they have lost electrons

Question 23

What observation could be made at the anode during the molten electrolysis of magnesium chloride!?

Answer 23

As Cl2 is a pale green gas. Some bubbles of pale green gas would be likely to be seen at the anode.

Question 24

What happens at the cathode during molten electrolysis !?

Answer 24

Metal ions gain electrons to form atoms

Question 25

What happens at the cathode half in the electrolysis of molten magnesium chloride!?

Answer 25

The Mg2+ ions are attracted to the cathode and they gain electrons to form neutral Mg atoms

Question 26

How many electrons do the Mg ions lose at the cathode to become neutral during the molten electrolysis of magnesium chloride?

Answer 26

As each Mg2+ ion has a 2+ charge they gain two electrons to each to become neutral

Question 27

Why don’t Mg2+ molecules form at the cathode during the molten electrolysis of magnesium chloride!?

Answer 27

Metals aren’t made up of molecules, so the atoms don’t pair up
Mg2+ Remains an atom

Question 28

What is the half equation of Mg at the cathode during the molten electrolysis of magnesium chloride!?

Answer 28

We write this as a half equation, showing the Mg2+ ions gaining electrons and becoming atoms

Question 29

Have the Mg2+ ions been oxidised or reduced during the molten electrolysis of magnesium chloride!?

Answer 29

The Mg2+ ions have been reduced because they have gained electrons

Question 30

What observation could be made at the cathode during the molten electrolysis of magnesium chloride!?

Answer 30

As Mg is a grey solid, some grey solid would form on the surface of the cathode