Electrolysis Flashcards Preview

Chemistry > Electrolysis > Flashcards

Flashcards in Electrolysis Deck (23):
0

Electrolysis is the extraction of...?

Aluminium

1

What is electrolysis used for and why is it so expensive?

•used for metals HIGH in the reactivity series
•more expensive because it requires more energy

2

At the cathode what type ions are attracted in electrolysis?

Cations

3

At the anode in electrolysis what type if ions are attracted?

Anions

4

Aluminium is unreactive, state 3 of it's uses... (They don't rust!)

Car bodies
Window frames
Structures

5

Why does aluminium seem unreactive?

OXIDE LAYER

6

What does the oxide layer on aluminium prevent?

Oxide layer prevents chemicals from colliding with aluminium. If the oxide later is removed, aluminium will react quite vigorously.

7

Why can't you use carbon to extract aluminium?

Carbon is lower in the reactivity series.

8

Why do the anodes need continuously replacing? (4)

•oxygen forms at the carbon anode
•carbon reacts with the oxygen to form carbon dioxide gas
•carbon electrode therefore gradually disappears

9

What temperature does electrolysis occur at?

955'c

10

Why do the carbon electrodes need to be replaced?

Burns away

11

Name a metal that can be added to aluminium to make an alloy...

Magnesium

12

What is the overall equation for ELECTROLYSIS OF ALUMINIUM OXIDE?

2Al2O3 -> 4Al + 3O2

13

Electrode equation at the cathode..

Al3+ + 3e -> Al

14

Electrode equation at the anode..

2O2- -> O2 + 4e-

15

What is cryolite?

A mixture of cryolite and aluminium oxide has a lower melting point than pure aluminium.

16

Give 4 properties of aluminium...

•low density
•strong
•ductile
•malleable

17

How does electrolytic reduction work in the extraction of aluminium?

Electricity is used to reduce aluminium oxide.

18

What kind if metals is electrolysis used for?

Metals high up in the reactivity series

19

When molten lead bromide undergoes electrolysis what forms at the cathode?

Grey solid coating on the electrode

20

What is the electrode equation at the cathode? (Lead bromide)

Pb2+ + 2e- = Pb (Pb gains electrons; REDUCTION)

21

What is the electrode equation at the anode (lead bromide)

2Br- = Br2 + 2e- (lose electrons; oxidation)

22

When molten lead bromide undergoes electrolysis what forms at the anode?

Bubbling and orange gas given off.