Metals And Extraction Flashcards
(24 cards)
What is an Ore
A rock which contains metals chemically combined with other substances
High concentration of metal and is extracted
What is oxidation in terms of oxygen
Gain of oxygen
What is reduction in terms of oxygen
Losss of oxygen
Two methods used to extract metal ores
Reduction with carbon- can only be used if the metal is less reactive than carbon
Electrolysis which can be done with all metals but needs a lot of electricity- high cost.
How would you extract iron
Iron less reactive then carbon so you could use reduction with carbon
Electrolysis - high cost for no reason-a lot of electricity
Chemical equation for reduction of iron with carbon
2Fe₂O₃(s) + 3C(s) → 4Fe(l) + 3CO₂(g)
How can aluminium be extracted
Aluminium more reactive then carbon so u need electrolysis
Molten ore goes through electrolysis the metal forms at the cathode
Why is aluminium oxide dissolved in molten cryolite
Has a very high melting point
When dissolved the electrolyte has a lower melting point reducing energy usage and cost
How can plants be used to extract metals
Phytoextraction
Plants grow in area with metals in the soil
Plants take metals through their roots and concentrate them in there shoots and leaves
These plants are burned and metal is taken from there ash
How can bacteria be used as an alternative for metal extraction
Bacterial extraction
Some bacteria absorb metal compounds
These bacteria produce solutions called leachates containing metals
Scrap iron can be used to remove metal from leachate
Limitations of biological methods of extraction
Only suitable for low grade ores with small quantities of metals.
Slow process
Require displacement or electrolysis in final step
How is metal resistance to oxidation related to reactivity
Oxidation is the lose of electrons
Metals lower in the reactivity series are less reactive
This means they are less likely to form at their cationss so are more resistant to oxidation
Advantages of recycling metals
Economically beneficial electrolysis is expensive
Less waste product so less landfill
Less energy required compared to electrolysis
More sustainable
What is a life cycle assessment
Analysis of the overall environmental inpact that a product may have during its lifetime
Factors considered in a life cycle assessment
Extraction and processing of raw materials
Manufacturing
Packaging and transportation
Use of the product
Disposal
What are the products of acid + metal
Salt + hydrogen
Fairly reactive metals
What do most metals react with
Cold water
Metal + water - Metal hydroxide + hydrogen
Oxygen
Metal + oxygen - metal oxide
What metal is the least reactive
Gold
Found as the metal itself and doesn’t react
Most metals are found as compounds
How can u tell the reactivity of a metal
If they react with water - very reactive
If they react with acid - reactive
If they react with oxygen - not that reactive
How do you tell if the reaction has taken place
Look for bubbles to see if hydrogen is produced
Displacement reaction
More reactive metal gradually disappears as it forms a solution
Less reactive metal coats the surface of the more reactive metal
Displacement reaction as redox reactions
More reactive metals form a cation and displace less reactive metal.
Losing electrons then being oxidised- loss of electrons.
Less reactive metals form atoms form negative ions as they are displaced
Gaining electrons and therefore being reduced- gain of electrons
Oxidation
Gain of oxygen
Reduction
Loss of oxygen
