Electrolysis

Question 1

What happens at the cathode?

Answer 1

The cathode is the negative electrode where hydrogen is produced unless the compound contains ions less reactive than hydrogen. In that case, the metal is produced instead.

Question 2

What happens at the anode?

Answer 2

The anode is the positive electron where oxygen is produced from OH- ions unless the compound contains halide ions. In that case, chlorides produce chlorine, bromide produce bromine, iodides produce iodine.

Question 3

What are the conditions for electrolysis to happen?

Answer 3

1) Cannot be in a solid state because the particle cannot move.
2) Has to be ionic compound.
3) Has to have free moving ions.

Question 4

What is an electrolyte?

Answer 4

An ionic compound in the molten state or dissolved in water.

Question 5

What is electrolysis?

Answer 5

A process in which electrical energy from a direct current supply, decomposes an electrolyte.

Question 6

What is an anion?

Answer 6

A negatively charged ion that moves to the positive electrode.

Question 7

What is a cation?

Answer 7

A positively charged ion that moves to the negative electrode.

Question 8

What happens during electrolysis?

Answer 8

1) Positively charged ions gain electrons and are reduced.
2) Negatively charged ionsnlose electrons and are oxidised.
3) During electrolysis, positively charged ions are attracted to the negative electrode and move to it
4) Negatively charged ions are attracted to the positive electrons and move to it during electrolysis.

Question 9

Why do solutions of an ionic compound contain H+ and OH- ions?

Answer 9

Water is a covalent compound. Some of its molecules naturally form ions.

Question 10

What is the apparatus used when investigating the change in mass of the anode and the cathode when copper sulfate solution is electrolysed using copper electrodes.

Answer 10

Eye protection
Beaker
Two strips of copper
Crocodile clips and leads
D.C. power supply
Copper sulfate solution
Filter paper
Balance

Question 11

What is the method used when investigating the change in mass of the anode and the cathode when copper sulfate solution is electrolysed using copper electrodes.

Answer 11

Measure and record the mass of each electrode. Complete electrolysis. Disconnect the two electrodes, carefully dry them with filter paper, and then weigh them again. Calculate the change in mass of each electrode.