3.5 Electrolysis 1 -Introduction

Question 1

What does the beaker contain?

Answer 1

An electrolyte

Question 2

What is an electrolyte?

Answer 2

A liquid or solution that contains an ionic compound where the ions are free to move

Question 3

How do you make a soluble ionic compound like Copper Sulphate become an electrolyte?

Answer 3

Dissolve it in water - the aqueous Copper Sulphate would be the electrolyte

Question 4

How do you make an insoluble ionic compound like Lead Bromide into an electrolyte?

Answer 4

Melt it to get a molten liquid

Question 5

In the electrolysis experiment, if you have Lead Bromide as the electrolyte, which ion would be positive?

Answer 5

Lead

Question 6

In the electrolysis experiment, if you have Lead Bromide as the electrolyte, which ion is negative?

Answer 6

Bromine

Question 7

What are electrodes?

Answer 7

Solid conductors that are usually made out of metal or carbon

Question 8

Which electrode is on the left of the beaker?

Answer 8

Negative - cathode

Question 9

What electrode is on the right of the beaker?

Answer 9

Positive - anode

Question 10

What piece of equipment in the electrolysis experiment is used to connect the two electrodes together?

Answer 10

Wire

Question 11

What is the wire used for in the electrolysis experiment?

Answer 11

So the electrons can flow

Question 12

What piece of equipment is used in the middle of the wire in between the two electrodes?

Answer 12

A power supply - usually a battery

Question 13

Why is a power supply used in the between the two electrodes in the electrolysis experiment?

Answer 13

To drive the flow of electrons

Question 14

What is electrolysis used to do?

Answer 14

Electricity is used to convert the ions in a compound back into their pure elemental forms by transferring electrons from the negative ions, to the positive ions.

Question 15

In the electrolysis experiment, if the electrolyte was Lead Bromide, which ion would be attracted to the positive anode?

Answer 15

Bromine

Question 16

What happens when the negatively charged Bromine ions move to the positive anode?

Answer 16

They will lose electrons - it will turn from a negatively charged ion to a neutral atom. In Bromine’s case, this will cause the atoms to pair up and form Bromine gas which then floats off.

Question 17

In the electrolysis experiment, if the electrolyte was Lead Bromide, which ion would be attracted to the negative cathode?

Answer 17

Lead

Question 18

What happens when the positively charged Lead ions move to the negative cathode?

Answer 18

They will gain electrons and the ions form pure lead which will then fall to the bottom of the beaker and form a layer of molten lead.

Question 19

When the positive metal or hydrogen ions in the electrolyte gain electrons, are they reduced or oxidised?

Answer 19

Reduced

Question 20

When the negative non-metal ions in the electrolyte lose electrons are they reduced or oxidised?

Answer 20

Oxidised

Question 21

Describe how Bromine’s ions transfer to the Lead

Answer 21

The 2 electrons from the Bromine ions are being passed to the positive anode and then being transported along the wire around to the negative cathode using the power of the battery. Then, the 2 electrons from the Bromine ions are given to the Lead ions, turning it into pure, neutral lead.

Question 22

An electrolysis cell has two electrodes. What is the name of the positive electrode?

Answer 22

Anode

Question 23

An electrolysis cell has two electrodes. What is the name of the negative electrode?

Answer 23

Cathode

Question 24

In electrolysis, which direction do the electrons travel?

Answer 24

Anode —> Cathode

Question 25

The electrodes in an electrolysis cell are normally made of inert carbon. What does the term ‘inert’ mean?

Answer 25

It is unreactive, so will not take place in the reaction.

Question 26

In terms of electrons, what does oxidation mean?

Answer 26

Loss of electrons

Question 27

In terms of electrons, what does reduction mean?

Answer 27

Gain of electrons

Question 28

In electrolysis, why does the compound you’re trying to separate need to be molten or dissolved?

Answer 28

So that the ions are free to move around (and go to their respective electrode)

Question 29

Why can’t an ionic solid be electrolysed?

Answer 29

The ions are in fixed positions and can’t move

Question 30

In electrolysis, which electrode would chloride ions (Cl-) be attracted to?

Answer 30

Anode