Electrolysis

Question 1

What is electrolysis?

Answer 1

The breaking down of a substance using electricity.

Question 2

What is the process of electrolysis?

Answer 2

An electric current is passed through an electrolyte (a molten or dissolved ionic compound), causing it to decompose.

Question 3

In electrolysis, what is oxidation?

Answer 3

Loss of electrons

Question 4

In electrolysis, what is reduction?

Answer 4

Gain of electrons

Question 5

What two processes occur during electrolysis?

Answer 5

Oxidation and reduction.

Question 6

What is the mnemonic for remembering oxidation and reduction?

Answer 6

OIL RIG

Oxidation
Is
Loss

Reduction
Is
Gain

Question 7

What are cations?

Answer 7

Positive ions

Question 8

What are anions?

Answer 8

Negative ions

Question 9

What is the cathode?

Answer 9

Negative electrode

Question 10

What is the anode?

Answer 10

Positive electrode

Question 11

Where do the cations in the electrolyte move towards?

Answer 11

The cathode (negative electrode).

Question 12

Where do the anions in the electrolyte move towards?

Answer 12

The anode (positive electrode).

Question 13

What happens to the cations when they move towards the cathode?

Answer 13

The cations are reduced (gain electrons).

Question 14

What happens to the anions when they move towards the anode?

Answer 14

The anions are oxidised (lose electrons).

Question 15

During electrolysis, what happens to ions as they gain or lose electrons?

Answer 15

They form uncharged substances and are discharged from the electrolyte.

Question 16

What do half equations show?

Answer 16

How electrons are transferred during reactions.

Question 17

How do you write half equations?

Answer 17

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

Question 18

What is an electrochemical cell?

Answer 18

A circuit, made up of the anode, cathode, electrolyte, a power source and the wires that connect the two electrodes.

Question 19

What is an electrolyte?

Answer 19

A liquid or gel which contains ions and can be decomposed by electrolysis.

Question 20

How do you set up an electrochemical cell, if your electrolyte is a solution?

Answer 20

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.