Topic 4 - Extracting metals and Equilibria Flashcards Preview

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Flashcards in Topic 4 - Extracting metals and Equilibria Deck (31)
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1
Q

Why are displacement reactions redox reactions?

A

Because oxidation and reduction happen simultaneously

  • more reactive metal is oxidised (to become an ion)
  • less reactive is reduced to become an atom
2
Q

Describe the general order of the Reactivity Series

A
  • Potassium at top with sodium and calcium
  • carbon below alluminium but above Zinc
  • Gold at bottom and silver
3
Q

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

A

More reactive ones eg potassium and sodium

4
Q

What is an ore

A

Ores contain enough of a metal to make a profit

its an oxide of a metal eg) aluminium is bauxite

5
Q

Which metals are found uncombined in earths crust

A

Gold and platinum are found in nuggets

6
Q

How can ores be extracted with carbon

A
  • It must be less reactive than carbon (so zinc and below)
  • Extracted chemicallu using carbon by reduction
  • Oxygen is removed from ore when reduced
7
Q

Example of word equation for extraction with carbon

A

2Fe2O3 + 3C = 4Fe + 3CO2

8
Q

How are metals extracted with electrolysis

A
  • More reactive than carbon
  • using electrolysis of molten compounds
  • once ore melted , metal is produced at cathode
9
Q

Positives and negatives of extracting metals with Carbon

A

Positive - Quicker process

Negative - produces polluting CO2 and also dangerous carbon monoxide

10
Q

Positives and negatives of extracting metals with Electrolysis

A

Positive- quick

Negative - more expensive

11
Q

Explain process of bioleaching

A

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

12
Q

Explain process of phytoextraction

A

-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

13
Q

Positives and negatives of bioleaching

A

+ smaller impact to environment

-longer process

14
Q

positives and negatives of phytoextraction

A

+ smaller impact to environment

- longer process as plants have to grow

15
Q

Why are reactions occurring at electrodes during electrolysis redox

A

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

16
Q

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

A

Oxidation- gains oxygen

Reduction - loses oxygen

17
Q

Overall how are all metals extracted

A

by reduction in their ores

18
Q

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

A

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

19
Q

What are the advantages and disadvantages of recycling metals

A
\+ 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
20
Q

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

A

alluminium
dont have to mine and cut down trees
making cans

21
Q

Advantages and disadvantages of recycling a product

A
\+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
22
Q

What are the 4 stages of a life cycle assessment

A

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

23
Q

What happens in reversible reactions

A

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

24
Q

What is the formation of ammonia? Chemical equation

A

2 NH3

Made in the haber process with N2 + 3 H2

25
Q

What are the conditions used in the haber process

A

450 degrees
200 atmospheres of pressure
Iron catalyst

26
Q

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

A
  • 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

27
Q

Which direction does heating move equilibrium

Exothermic or endothermic?

A

Right (products) Exothermic

28
Q

Which direction does cooling move equilibrium

Exothermic or endothermic?

A

Left (products) Endothermic

29
Q

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

A

side with fewer moles of gas to reduce pressure

30
Q

If you increase the concentration of REACTANTS where does equilibrium shift

A

Moves to the right to use reactants and make more product

31
Q

If you increase the concentration of PRODUCTS where does equilibrium shift

A

left to make more reactants