Electrolysis Flashcards
How do you chemically change an electrolyte
Electrolytes are chemically changed when an electric current is passed through them.
Define an electrolyte
An electrolyte is a substance that conducts electricity when dissolved in water.
Give 3 examples of electrolytes
Acids, bases and salt water
Define electrolysis
Electrolysis is the breaking up of a substance due to the passage of an electric current through it in an aqueous solution or when molten
In electrolysis what are the electrodes connected to?
The positive and negative terminals of a d.c power supply
How do you get electricity to flow through water in electrolysis?
Dip the electrodes in to an electrolyte
What is the name given to positive ions
Cations
State whether the cathode is positively or negatively charged
Negative
Which electrode are cations attracted to?
The cathode
What is the name given to negative ions?
Anions
State whether the anode is positively or negatively charged
Positive
Which electrode are anions attracted to?
Anode
Which electrode does oxidation take place?
Anode
Which electrode does reduction take place?
Cathode
Define electroplating
A layer of metal is put on to the surface of another metal
Give an example of an everyday item that has been electroplated
Cutlery is made from nickel and coated in silver
Define electrolysis of an aqueous solution
This is a complex reaction due to the presence of a number of species
In an aqueous solution water can be oxidised and reduce. Explain why this is
Water can be split into H+ ions and OH- ions. H+ (positive charge) is reduced at the cathode (negative charge. OH- (negative charge) is oxidised at the anode (positive charge)
Name the factors that determine what is oxidised and reduced
Type of electrodes
The ease of oxidation and reduction of the different species
Why can’t copper electrodes be used in the electrolysis of an aqueous solution
It would react with the solution
Give an example of electrodes that wouldn’t react with the solution
Platinum electrodes
In electrolysis of acidified water what 3 things are suspended in the solution?
2-
H+) Hydrogen (H20) Water & (So4
Which is more easily oxidised water or sulfuric acid?
Water
At the anode water is oxidised, represent this in an equation
_
H2O-> 2H + 1/2O2 +2e
At the cathode hydrogen is reduced, represent this in an equation
+ _
2H + 2e -> H2
