Metals and Their Uses

Ore: A rock that contains enough metal to make it economical to extract

Native state: The element in an uncombined state

The ore is mostly an oxide of the metal & needs to be mined & concentrated before the metal can be extracted & purified

We can find gold & other unreactive metals in their native state

Metals can be extracted by reduction or electolysis, depending on its' reactivity

Reduction:

• The metal is extracted by reduction with carbon
• Carbon takes away the oxygen-
  • 2Fe  O     + 3C           4Fe + 3CO
  • Iron oxide + Carbon    Iron + Carbon dioxide
• If the metal is more reactive than carbon- higher than carbon in the reactivity series-, it needs to be extracted by electroylsis
• This is because carbon can only take the oxygen away from metals less reactive than itself
• Carbon is first extracted by reduction, then made purer with electolysis
  • This is becuase copper is used to make electrical wiring and pure copper is a much better conductor

Electrolysis:

• This process is much more expensive because it uses a lot of energy
• This is used to extract metals that are more reactive than carbon
• It requires a liquid to conduct the electricity, called an electrolyte
• Electrolytes are often metal salt solutions made from the ore-eg. copper sulphate- or molten metal oxides
• The electrolyte has free ions which conduct electricity
• Electrons are taken away from the anode and given to the cathode

Extracting Iron:

• Iron is extracted from its ore by reacting it with carbon in a blast furnace
• A blast furnace has hot air blasted in at the bottom

The atoms in pure iron are arranged in densely packed layers, which can easily slide over one another, making pure iron very soft & not of much use

The atoms of different elements in steel are different sizes, which makes it difficult for the layers to slide over one another, so steel is stronger

• Tungsten Steel:
  • Contains Tungsten, Steel
  • Very hard & resists high temperatures
  • Used for tools
• Titanium Steel: 
  • Contains Titanium, Steel
  • Lightweight, Heat resistans
  • Used in air/ spacecrafts

Copper can be extracted by:

Phytomining:

• Plants absorb copper ions from the ore
• The plants are burned and metal is extracted

Bioleaching:

• Bacteria feed on on low grade ores
• This seperates the copper from the ore & can be extracted by filtering

Aluminium & Titanium Alloys:

• Useful because they are strong & have a low density
• Don't corrode
• Expensive to extract