🔹topic 5 - Calculations And Electrolysis

Question 1

What is an ore?

Answer 1

A rock with enough metal compounds to be economical to extract the metal

Question 2

In sodium chloride, what’s the electrolyte?

Answer 2

NaCl

Question 3

Why don’t you need electrolysis to extract iron from iron oxide?

Answer 3

It’s less reactive than carbon so can be extracted by heating it with carbon

Question 4

Why does electrolysis of calcium chloride have to happen to get calcium?

Answer 4

As calcium is more reactive that carbon do heating them won’t work

Question 5

Why does aluminium oxide have a high melting point in terms of bonding and structure?

Answer 5

As it’s an ionic lattice structure with many strong electrostatic forces of attraction which require a lot of energy to overcome

Question 6

How can graphite conduct electricity?

Answer 6

As each carbon atom in graphite is bonded to 3 others meaning there is a free electron which can carry a charge

Question 7

Is electrolysis exothermic or endothermic?

Answer 7

Endothermic as it requires energy and more energy is taken in than released

Question 8

Describe the uses of copper and it’s properties that suit it to that use

Answer 8

Used in electrical wires as it’s a good electrical conductor and is malleable
Used in pipes as it’s good conductor of heat

Question 9

Give 4 physical properties of transition metals

Answer 9

• hard and strong
• good electrical conductors
• good heat conductors
• have high melting points

Question 10

Give two chemical properties of electrical conductors

Answer 10

• They form coloured compounds

- can act as a catalyst in reactions

Question 11

How are bioleaching and phyto mining used to concentrate the amount of copper in ores.

Answer 11

Bioleaching is used as it’s where bacteria concentrate copper ions which can be extracted

Phyto mining is used as it’s where copper ions concentrated in plants are burned so ions can be extracted

Question 12

Give some typical properties of a metal

Answer 12

Strong, conductor of electricity and high melting point

Question 13

Why does magnesium conduct electricity?

Answer 13

s the sea of delocalised

Question 14

What is magnesium becoming magnesium and oxygen an example of?

Answer 14

Thermal decomposition

Question 15

What happens when lithium reacts with water?

Answer 15

It looses an electron to become a lithium ion

Question 16

When comparing reaction of metals, why is it important to use the same acid?

Answer 16

As acid concentration may effect the rate of reaction

Question 17

Why are some metals more reactive than others?

Answer 17

As they may loose electrons more easily

Question 18

What is an ore?

Answer 18

A rock that contains enough metal compounds that it’s economic to mine

Question 19

Why should we be finding alternate methods of electrolysis when extracting metals?

Answer 19

As ore reserves are running out and electrolysis requires a lot of energy

Question 20

What are the steps to phytomining

Answer 20

1. Grow plants on or near the low grade ore
2. Harvest the grown plants and burn them
3. The ash contains metal compounds that can be purified during electrolysis

Question 21

What are the steps to bioleaching?

Answer 21

1. Bacteria are grown on or near low grade ore
2. They they then produce a solution called leachate containing the metal compound which can be purified using electrolysis

Question 22

What are the 4 stages of lifecycle assessments?

What should you consider within each stage?

Answer 22

1. Obtaining and processing the raw material
   (Renewable or not, how much land is used? deforestation in production?
2. Manufacturing and packaging the product
   (Energy needed e.g. some need electrolysis while others require reduction with carbon)
3. Using the product
   Some items can only be used once, lack of durability, efficiency
4. Disposal of the product
   Can it be recycled or is it incinerated or disposed in a landfill e.c.t

Question 23

Why is cryolite added to aluminium oxide?

Answer 23

To lower it’s melting point

Question 24

Give 2 properties specific to transition metals

Answer 24

Can act as a catalyst and form coloured compounds

Question 25

What does it mean that transition metals have variable oxidation states?

Answer 25

They can form ions with different charges

Question 26

Name 3 transition metals used in car parts

Answer 26

Platinum, palladium and rhodium

Question 27

Why are nano particles good catalysts?

Answer 27

They have a high surface to volume ratio so there are a large number of active sites for the reaction to happen

Question 28

Why are coins not made of pure copper?

Answer 28

As pure copper would be too soft and the coin would dent