C6: Electrolysis

Question 1

What are the 3 most common elements in the earths crust?

Answer 1

• Oxygen
• Silicon
• Alluminium

Question 2

What is the most common metal in the earths crust?

Answer 2

Alluminium

Question 3

To extract a metal from it’s core, what must happen to the metal oxide?

Answer 3

The oxygen must be removed

Question 4

What is the removal of oxygen called?

Answer 4

Reduction

Question 5

What is the gain of oxygen called?

Answer 5

Oxidation

Question 6

When do displacement reactions take place?

Answer 6

When a metal is added to a solution containing a less reactive metal

Question 7

True or False: A more reactive metal will displace a less reactive metal from a compound containing the less reactive metal?

Answer 7

True

Question 8

When is electrolysis needed to extract metals from their ores?

Answer 8

When metals that are more reactive than carbon need to be extracted from their ores

Question 9

What is electrolysis?

Answer 9

The breaking down of a compound using electrcity

Question 10

True or False: The metal compound must be in molten or aqueous solution in order for electrolysis to work?

Answer 10

True

Question 11

What is the solution used in an electrolysis set up called?

Answer 11

The electrolyte

Question 12

What are the two rods placed inside the electrolyte during electrolysis called?

Answer 12

Electrodes

Question 13

What is the positive electrode called?

Answer 13

The Anode

Question 14

What is the negative electrode called?

Answer 14

The Cathode

Question 15

In terms of electrons, what is reduction?

Answer 15

The gain of electrons

Question 16

In terms of electrons, what is oxidation?

Answer 16

The loss of electrons

Question 17

What is the acronym that can be used to help us remember what reduction and oxidation mean?

Answer 17

OILRIG

Oxidation
Is
Loss
Reduction
Is
Gain

Question 18

What electrode are the positive ions attracted to?

Answer 18

The negative Cathode

Question 19

What electrode are the negative ions attracted to?

Answer 19

The positive Anode

Question 20

What is cryolite?

Answer 20

A substance that can be added to substances to help dissolve them so the temperature needed to melt the substance in order for electrolysis to happen is lower

Question 21

What are the benefits of cryolite?

Answer 21

It lowers the melting point of substances so less energy is needed to melt them for electrolysis to happen, reducing overall costs

Question 22

When electrolysing water, what are the Hydrogen ions attracted to?

Answer 22

Hydrogen ions are positive so they are attracted to the negative cathode

Question 23

When electrolysing water, what are the Hydroxide ions attracted to?

Answer 23

Hydroxide ions are negative so they are attracted to the positive anode

Question 24

In electrolysis, do the electrons travel from the Anode –> Cathode or from the Cathode –> Anode?

Answer 24

From the Anode –> Cathode

Question 25

What is the rule for determining which ion will be oxidised at the anode in an aqueous solution?

Answer 25

It will always be hydroxide (OH-) unless a halide is present (such as Cl- or Br-)

Question 26

What is the rule for determining which ion will be reduced at the cathode in an aqueous solution?

Answer 26

The ion of the least reactive element will always be reduced (An alternative way of thinking about it is that it will always be H+ unless if Cu2+ is present)