C6 Electrolysis Flashcards
What does the suffix ‘lysis’ in electrolysis mean?
Breaking
Define electrolysis.
The decomposition of an ionic compound using electricity
What is an electrolyte?
An ionic compund which is melted or dissloved in water.
What is PANIC?
Positive Anode
(P) (A)
Negative Cathode
(N) (I) (C)
What is an anode?
Positive electrode
What is a cathode?
Negative electrode
What occurs at the anode during electrolysis?
Oxidation occurs at the anode.
What occurs at the cathode during electrolysis?
Reduction occurs at the cathode.
In aqueous electrolysis what is discharged (reduced) at the cathode?
Hydrogen - unless there is a less reactive metal
In aqueous electrolysis what is oxidised at the anode?
Halide ions are oxidised first, if there are no halide ions then hydroxide ions are oxidised
What is brine?
Concentrated sodium chloride solution (that can undergo electrolysis to produce chlorine gas, hydrogen gas and sodium hydroxide solution)
What does inert mean?
Unreactive
What is an anion?
A negative ion.
What is a cation?
Positive ion,
Which ions are attracted to the cathode?
Cations
- because the cation is a positive ion and the cathode is a negative electrode
Which ions are attracted to the anode?
Anions
- because anions are negative ions and anode is the positive electrode
Why can electrolysis only occur when an ionic compound is molten or in aqueous solution?
Because in an ionic compound ions can only move freely when melted or dissolved in water.
What is oxidation in electrolysis?
Loss of electrons.
What is reduction in electrolysis?
Gain of electrons.
Why is cryolite used in the manufacture of aluminium?
It lowers the melting point of aluminium oxide, reducing energy costs.
