5.5.1- Molten Electrolysis Flashcards
What is electrolysis !?
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)
Label:
What is the role of the electrodes !?
There are two electrodes, which connect the substance into the circuit
What is the positive (+) electrode called !?
The positive electrode is called the anode
What is the negative (-) electrode called !?
The negative electrode is called the cathode
What material must the electrode be made out of?
The electrodes must be made from a solid that conducts electricity, but is inert
Definition of inert:
Unreactive
What are electrodes usually made out of !?
Usually one of graphite (cheap) or platinum (expensive) are used
What is the electrolyte !?
The electrolyte is the substance to be broken down, and it needs to conduct electricity
What are the only compounds that conduct electricity !?
The only compounds that conduct electricity are ionic compounds that are molten or dissolved, so the ions are free to move
Why won’t solid ionic compounds work within molten electrolysis?
Solid ionic compounds won’t work because the ions can’t move
Why won’t covalent compounds work within molten electrolysis?
covalent compounds won’t work because the molecules aren’t even charged
What are cations !?
Positive ions are called cations because they are attracted to the cathode
What are anions !?
The negative ions are called anions because they’re attracted to the anode
What does the electrolysis of a molten ionic compound produce !?
Electrolysis of a molten ionic compound produces its elements
COMPOUND ➡️ ELEMENTS
What are the two-halves of electrolysis!?
The anode half
and
the cathode half
What happens at the anode half in the electrolysis of molten magnesium chloride!?
The Cl- ions are attracted to the anode and they lose electrons to form neutral Cl atoms.
How many electrons do the Cl ions lose at the anode to become neutral during the molten electrolysis of magnesium chloride?
as each Cl ion has a 1- charge. They lose one electron each to become neutral.
Why do Cl2 molecules form at the anode during the molten electrolysis of magnesium chloride!?
Nonmetals are made up of diatomic molecules so the Cl atoms pair up to form Cl2 molecules.
What happens at the anode during molten electrolysis!?
Nonmetal ions lose electrons to form molecules
What is the half equation of Cl at the anode during the molten electrolysis of magnesium chloride!?
We write this as a half equation, showing the Cl- ions, losing electrons and becoming molecules.
Have the Cl- ions been oxidised or reduced during the molten electrolysis of magnesium chloride!?
The Cl- ions have been oxidised because they have lost electrons
What observation could be made at the anode during the molten electrolysis of magnesium chloride!?
As Cl2 is a pale green gas. Some bubbles of pale green gas would be likely to be seen at the anode.
What happens at the cathode during molten electrolysis !?
Metal ions gain electrons to form atoms
What happens at the cathode half in the electrolysis of molten magnesium chloride!?
The Mg2+ ions are attracted to the cathode and they gain electrons to form neutral Mg atoms
How many electrons do the Mg ions lose at the cathode to become neutral during the molten electrolysis of magnesium chloride?
As each Mg2+ ion has a 2+ charge they gain two electrons to each to become neutral
Why don’t Mg2+ molecules form at the cathode during the molten electrolysis of magnesium chloride!?
Metals aren’t made up of molecules, so the atoms don’t pair up
Mg2+ Remains an atom
What is the half equation of Mg at the cathode during the molten electrolysis of magnesium chloride!?
We write this as a half equation, showing the Mg2+ ions gaining electrons and becoming atoms
Have the Mg2+ ions been oxidised or reduced during the molten electrolysis of magnesium chloride!?
The Mg2+ ions have been reduced because they have gained electrons
What observation could be made at the cathode during the molten electrolysis of magnesium chloride!?
As Mg is a grey solid, some grey solid would form on the surface of the cathode
