Topic 4 - Extracting metals and Equilibria

Question 1

Why are displacement reactions redox reactions?

Answer 1

Because oxidation and reduction happen simultaneously

• more reactive metal is oxidised (to become an ion)
• less reactive is reduced to become an atom

Question 2

Describe the general order of the Reactivity Series

Answer 2

• Potassium at top with sodium and calcium
• carbon below alluminium but above Zinc
• Gold at bottom and silver

Question 3

Which elements in the reactivity series are more likely to form cations

Answer 3

More reactive ones eg potassium and sodium

Question 4

What is an ore

Answer 4

Ores contain enough of a metal to make a profit

its an oxide of a metal eg) aluminium is bauxite

Question 5

Which metals are found uncombined in earths crust

Answer 5

Gold and platinum are found in nuggets

Question 6

How can ores be extracted with carbon

Answer 6

• It must be less reactive than carbon (so zinc and below)
• Extracted chemicallu using carbon by reduction
• Oxygen is removed from ore when reduced

Question 7

Example of word equation for extraction with carbon

Answer 7

2Fe2O3 + 3C = 4Fe + 3CO2

Question 8

How are metals extracted with electrolysis

Answer 8

• More reactive than carbon
• using electrolysis of molten compounds
• once ore melted , metal is produced at cathode

Question 9

Positives and negatives of extracting metals with Carbon

Answer 9

Positive - Quicker process

Negative - produces polluting CO2 and also dangerous carbon monoxide

Question 10

Positives and negatives of extracting metals with Electrolysis

Answer 10

Positive- quick

Negative - more expensive

Question 11

Explain process of bioleaching

Answer 11

Uses bacteria to separate metals from their ores
bacteria get energy from bonds and break them separating the metal from ore in process
solution produced is then separated with electrolysis

Question 12

Explain process of phytoextraction

Answer 12

-Growing plants in soil containing metal compound
-as they have no use for it its stored in leaves and
these can be harvested dried and burned
- the ash containing metal compounds can be extracted by electrolysis or displacement

Question 13

Positives and negatives of bioleaching

Answer 13

+ smaller impact to environment

-longer process

Question 14

positives and negatives of phytoextraction

Answer 14

+ smaller impact to environment

- longer process as plants have to grow

Question 15

Why are reactions occurring at electrodes during electrolysis redox

Answer 15

Because products at cathode have been reduced and ones at the anode have been oxidised

Question 16

what is the meaning of oxidation and reduction in terms of oxygen

Answer 16

Oxidation- gains oxygen

Reduction - loses oxygen

Question 17

Overall how are all metals extracted

Answer 17

by reduction in their ores

Question 18

What is the relation of how easily a metal is oxidised to the reactivity series?

Answer 18

The more reactive metals are oxidised more easily

makes sense as more energy is needed to break more reactive ones with electrolysis

and that gold is found unreacted as nuggets

Question 19

What are the advantages and disadvantages of recycling metals

Answer 19

\+ we dont need to keep mining which is bad for the environment 
\+cuts down rubbish to landfill
\+saves energy
-still does need energy
-need to be manually separated

Question 20

describe a process where a metal is recycled for a different use

Answer 20

alluminium
dont have to mine and cut down trees
making cans

Question 21

Advantages and disadvantages of recycling a product

Answer 21

\+protects the environment 
\+decreases waste to landfill
\+conserves resources and energy
\+creates jobs
\+saves money

• not completely widespread on a large scale
• products aren’t as durable as before so can go down in quality

Question 22

What are the 4 stages of a life cycle assessment

Answer 22

Choice of material- costs, needing extraction, raw material?
Manufacturing- how much energy is needed, waste products, pollution?
Product use- does it damage environment or give off toxic fumes?
Disposal- can it be recycled or burnt

Question 23

What happens in reversible reactions

Answer 23

can go forwards and backwards so it can produce the original reactants.

Question 24

What is the formation of ammonia? Chemical equation

Answer 24

2 NH3

Made in the haber process with N2 + 3 H2

Question 25

What are the conditions used in the haber process

Answer 25

450 degrees
200 atmospheres of pressure
Iron catalyst

Question 26

How does changing each of the factors needed in the Haber Process effect the yield

Answer 26

• 200 atmospheres to favor the forwards reaction to the right to make more product
• 450 degrees to compromise between max. yield and rate of reaction as too high equilibrium shifts the wrong way
• Iron catalyst makes reaction speed up so equilibrium is reached faster (doesn’t effect position of equilibrium or % yield)

-Equilibrium shifts to right to favor product

Question 27

Which direction does heating move equilibrium

Exothermic or endothermic?

Answer 27

Right (products) Exothermic

Question 28

Which direction does cooling move equilibrium

Exothermic or endothermic?

Answer 28

Left (products) Endothermic

Question 29

If you increase the pressure which direction does equilibrium shift to?

Answer 29

side with fewer moles of gas to reduce pressure

Question 30

If you increase the concentration of REACTANTS where does equilibrium shift

Answer 30

Moves to the right to use reactants and make more product

Question 31

If you increase the concentration of PRODUCTS where does equilibrium shift

Answer 31

left to make more reactants