2e Extraction and uses of metals

spec point 2.22-2.27

how and where are metals found?

metals are found as metal oxides in ores found in the Earth’s core. gold is unreactive so is usually found in it’s pure form

what 4 ways are metals extracted from ores?

• heating with carbon

• electrolysis

• phytoextraction

• bacterial extraction

how is carbon used to extract metals from ores?

• carbon is heated with the metal oxide

• it combines with the oxygen to form CO2 → leaves the metal on it’s own

• the metal becomes reduces and the carbon becomes oxidised

why is carbon only used to extract some metals?

it can only be used for metals less reactive than carbon so that carbon can displace them

how is electrolysis used to extract metals?

it is used to extract metals which are more reactive than carbon such as aluminium as they can’t be displaced

why is heating with carbon better than electrolysis?

electrolysis is very expensive as it uses a lot of energy

phytoextraction

• some plants can absorb metal compounds through their roots and concentrate the compounds.

• the plants can then be burnt to produce an ash that contains the metal compounds

bacterial extraction

some bacterial absorb metal compounds and produce solutions called leachates which contain the metals

properties of aluminium

low density, corrosion-resistant

uses of aluminium

aircraft, trains, overhead power cables, saucepans and cooking foil

properties of copper

soft and easily bent, good conductor of electricity, does not react with water

uses of copper

used for electrical wiring and plumbing

properties of iron from a blast furnace

hard, but too brittle for most uses, so converted to steel

properties of pure iron

too soft for many uses

properties of low carbon steel

0.25% carbon, easily shaped,

uses of low carbon steel

car body panels

properties of high carbon steel

2.5% carbon, hard

uses of high carbon steel

cutting tools

properties of stainless steel

chromium & nickel, resistant to corrosion

uses of stainless steel

cutlery and sinks

what is an alloy?

a mixture of two or more elements where at least one is a metal

why are alloys made?

pure copper, gold, iron and aluminium are all too soft for everyday uses and so are mixed with small amounts of similar metals to make them harder for everyday use — gold jewellery is usually an alloy with silver, copper and zinc

why are alloys harder than pure metal?

• in a pure metal, the ions are all the same size and are in a regular arrangement of layers, meaning that they can slide over each other easily, making them soft.

• in an alloy, there are different sized ions, which disrupts the regular arrangement and prevents layers being able to slide over each other so easily.