C1.3 - Metals and Their Uses

Displacement

• metals less reactive than carbon can be extracted from oxides by heating with carbon
• a reduction reaction takes place as carbon removes the oxygen from the oxide

Smelting

• heating the ore strongly in a furnace
• requires huge amounts of energy
• produces impure copper which can be purified by electrolysis

Bioleaching

• uses bacteria to produce solutions containing metal ( copper ) compounds. The metal ( copper ) can then be extracted from this solution.

Phytomining

• use plants to absorb metal compounds, burn plants and metal separated from ash

• an ore contains enough metal for it to be economically viable to extract the metal
• some unreactive metals, such as gold, are found in the earth as the metal ( native ) and can be extracted by physical methods such as panning
• alloys are mixtures of metals, or a metal and at least one other element
• the added element distrurbs the regular arrangement of the metal atoms, so the layers do not slide over each other easily. Therfore, they are stronger and harder.

– iron is extracted by reduction using carbon in a blast furnace

( however, the iron produced contains only 96% iron, so it is hard and brittle )

• pure iron, copper, gold and aluminium are soft and easily bent - made into alloys - harder and keep their shape

• steel is an alloy made from iron and carbon
• in steel, the amount of carbon and / or other elements determines it's properties:
• steel with a low carbon content is soft and easily shaped ( mild steel ) eg. for cars
• steel with a high carbon content is hard and strong eg. for screwdrivers
• stainless steel contains chromium and nickel - hard and resistant to corrosion eg. for cutlery

Aluminium:

• low density ( lightweight )
• resistant to corrosion
• not very strong
• can be extracted by electrolysis
• drink cans, window frames and aeroplanes

Titanium:

• low density ( lightweight )
• resistant to corrosion
• very strong
• extracted from its ore - several stages and large amounts of energy = expensive
• titanium oxide can be reduced by carbon ( brittle )
• aeroplanes, nuclear reactors and replacement hip joints

• central block on periodic table
• good conductors of heat and electricity
• strong, but malleable ( easily bent or hammered into shape )
• useful for buildings, vehicles, containers, pipes and wires

• group or materials being developed to meet demands of modern engineering and manufacturing
• respond to changes in environment eg. tempurature, moisture, pH...
• shape memory alloys remember their shape, can be deformed, but when heated return to original shape