Extraction and uses of metals Flashcards
How are most metals found?
They are extracted from ores found in the Earth’s crust and unreactive metals are often found as the uncombined element
What does the method used for metal extraction depend upon?
Its position in the reactivity series?
What method is used to extract metals below C?
Heating with carbon
What method is used to extract metals above C?
Electrolysis
What some properties of aluminium?
- Low density and strength (when its alloyed)
- Ability to conduct electricity and heat
- Resistance to corrosion due to a very thin but very strong layer of aluminium oxide on the surface preventing anything else reaching the surface and reacting with it
- More expensive than steel due to the cost of electricity for electrolysis
What are some uses of aluminium?
- Overhead power cables (low density and electrical conductor)
- Aeroplanes (low density and strong
- Saucepans (resistant to corrosion)
What is mild steel?
An alloy of iron with about 0.25% carbon
What are some properties of mild steel?
- Hardness
- Strength
- Malleable
- Ductile
- More dense than aluminium
- Rusts
What are some uses of mild steel?
Nails, car bodies, ships, girders and bridges
What is high-carbon steel?
An alloy of iron with 0.6-1.2% carbon
What are some properties of high-carbon steel?
- Harder than mild steel
- More resistant to wear than mild steel
- Brittle (not as malleable and ductile)
What is a use of high-carbon steel?
Cutting tools
What is stainless steel?
An alloy of iron with nickel and chromium
What are some properties of stainless steel?
- Very resistant to corrosion because the chromium forms an oxide layer the same way as aluminium
- More expensive than mild steel
What are some uses of stainless steel?
Kitchen sinks, saucepans, knives, forks, gardening tools, brewing, dairy production and chemical industries where corrosion-resistant vessels are essential
What are some uses of copper?
- Electrical wires (very good conductor and ductile)
- Pots and pans (very good conductor, very unreactive and malleable)
- Water pipes (unreactive and malleable)
- Surfaces in hospitals (antimicrobial properties and malleable)
Alloy
A mixture of a metal with one or more elements, usually other metals and carbon
Why do alloys tend to be harder and stronger?
Due to the different-sized atoms preventing the layers sliding over each other
