Electrolysis Flashcards
What is electrolysis?
The breaking down of a substance using electricity.
What is the process of electrolysis?
An electric current is passed through an electrolyte (a molten or dissolved ionic compound), causing it to decompose.
In electrolysis, what is oxidation?
Loss of electrons
In electrolysis, what is reduction?
Gain of electrons
What two processes occur during electrolysis?
Oxidation and reduction.
What is the mnemonic for remembering oxidation and reduction?
OIL RIG
Oxidation
Is
Loss
Reduction
Is
Gain
What are cations?
Positive ions
What are anions?
Negative ions
What is the cathode?
Negative electrode
What is the anode?
Positive electrode
Where do the cations in the electrolyte move towards?
The cathode (negative electrode).
Where do the anions in the electrolyte move towards?
The anode (positive electrode).
What happens to the cations when they move towards the cathode?
The cations are reduced (gain electrons).
What happens to the anions when they move towards the anode?
The anions are oxidised (lose electrons).
During electrolysis, what happens to ions as they gain or lose electrons?
They form uncharged substances and are discharged from the electrolyte.
What do half equations show?
How electrons are transferred during reactions.
How do you write half equations?
1) Put one of the things being oxidised or reduced on one side of an arrow, and the thing it gets oxidised or reduced to on the other.
2) Balance up the numbers of atoms just like in a normal equation.
3) Then add electrons (written e ^-) on to one side to balance up the charges.
e.g. 2H+ + 2e- → H2
What is an electrochemical cell?
A circuit, made up of the anode, cathode, electrolyte, a power source and the wires that connect the two electrodes.
What is an electrolyte?
A liquid or gel which contains ions and can be decomposed by electrolysis.
How do you set up an electrochemical cell, if your electrolyte is a solution?
1) Get two inert (unreactive) electrodes, e.g. graphite or platinum electrodes.
2) Clean the surfaces of the electrodes using some emery paper (or sandpaper).
3) From this point on, be careful not to touch the surfaces of the electrodes with your hands - you could transfer crease back onto the strips.
4) Place both electrodes into a beaker filled with your electrolyte.
5) Connect the electrodes to a power supply using crocodile clips and wires. When you turn the power supply on, a current will flow through the cell.
