Electrolysis Flashcards
Summary (19 cards)
What happens to ions when an ionic substance is melted or dissolved?
Ions are free to move about within the liquid or solution.
What is electrolysis?
The process of breaking down a substance, specifically an electrolyte, by passing a current through it.
Which ions move to the cathode during electrolysis?
Positively charged ions.
Which ions move to the anode during electrolysis?
Negatively charged ions.
What is produced at the electrodes during electrolysis?
Elements are discharged at the electrodes.
What is produced at the cathode when a simple ionic compound like lead bromide is electrolysed?
Metal (lead).
What is produced at the anode when a simple ionic compound like lead bromide is electrolysed?
Non-metal (bromine).
Why are metals that are more reactive than carbon extracted by electrolysis?
They are too reactive to be extracted by reduction with carbon.
What is used as the positive electrode in the electrolysis of aluminium oxide?
Carbon.
Why is cryolite mixed with aluminium oxide during electrolysis?
To lower the melting point and reduce costs.
What happens to the positive electrodes during the electrolysis of aluminium?
They need to be continually replaced because they react with oxygen to form carbon dioxide.
What determines the ions discharged when an aqueous solution is electrolysed?
The relative reactivity of the elements involved.
What is produced at the cathode during the electrolysis of aqueous solutions?
Hydrogen, unless the metal is less reactive than hydrogen.
What is produced at the positive electrode if OH- and halide ions are present?
One of the halide ions (Cl-, Br-, I-).
What is produced at the positive electrode if no halide ions are present during electrolysis?
Oxygen.
What do water molecules break down into during electrolysis of aqueous solutions?
H+ ions and OH- ions.
What is represented by the symbol ‘e-‘ in half equations?
Electrons.
What does the half equation X+ -> X represent at the negative electrode?
Reduction of positive ions.
What does the half equation X- -> X represent at the positive electrode?
Oxidation of negative ions.
