Topic 4 - Extracting metals and Equilibria Flashcards
Why are displacement reactions redox reactions?
Because oxidation and reduction happen simultaneously
- more reactive metal is oxidised (to become an ion)
- less reactive is reduced to become an atom
Describe the general order of the Reactivity Series
- Potassium at top with sodium and calcium
- carbon below alluminium but above Zinc
- Gold at bottom and silver
Which elements in the reactivity series are more likely to form cations
More reactive ones eg potassium and sodium
What is an ore
Ores contain enough of a metal to make a profit
its an oxide of a metal eg) aluminium is bauxite
Which metals are found uncombined in earths crust
Gold and platinum are found in nuggets
How can ores be extracted with carbon
- It must be less reactive than carbon (so zinc and below)
- Extracted chemicallu using carbon by reduction
- Oxygen is removed from ore when reduced
Example of word equation for extraction with carbon
2Fe2O3 + 3C = 4Fe + 3CO2
How are metals extracted with electrolysis
- More reactive than carbon
- using electrolysis of molten compounds
- once ore melted , metal is produced at cathode
Positives and negatives of extracting metals with Carbon
Positive - Quicker process
Negative - produces polluting CO2 and also dangerous carbon monoxide
Positives and negatives of extracting metals with Electrolysis
Positive- quick
Negative - more expensive
Explain process of bioleaching
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
Explain process of phytoextraction
-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
Positives and negatives of bioleaching
+ smaller impact to environment
-longer process
positives and negatives of phytoextraction
+ smaller impact to environment
- longer process as plants have to grow
Why are reactions occurring at electrodes during electrolysis redox
Because products at cathode have been reduced and ones at the anode have been oxidised
what is the meaning of oxidation and reduction in terms of oxygen
Oxidation- gains oxygen
Reduction - loses oxygen
Overall how are all metals extracted
by reduction in their ores
What is the relation of how easily a metal is oxidised to the reactivity series?
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
What are the advantages and disadvantages of recycling metals
\+ 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
describe a process where a metal is recycled for a different use
alluminium
dont have to mine and cut down trees
making cans
Advantages and disadvantages of recycling a product
\+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
What are the 4 stages of a life cycle assessment
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
What happens in reversible reactions
can go forwards and backwards so it can produce the original reactants.
What is the formation of ammonia? Chemical equation
2 NH3
Made in the haber process with N2 + 3 H2
