Few metals in the earth's crust are so unreactive that they exist in their native state, ie gold and silver
A metal ore contains enough of the metal to make it economically worth extracting the metal
The reactivity series is useful in helping to decide how to extract a metal
Metals less reactive than Carbon can be extracted by reacting with Carbon. A reduction reaction removes the oxygen from a metal oxide.
Iron is removed from iron oxide by reducing it with carbon in a blast furnace.
Other raw materials used to make iron are Haematite (iron oxide and sand) and Coke (made from coal and almost pure carbon, it is the reducing agent)
Limestone is also added to remove any impurities
The coke burns at high temperatures to produce Carbon Dioxide which reacts again with the Coke to form Carbon Monoxide. This react with the iron oxide removing the oxygen and leaving molten iron which is then tapped off from the bottom of the furnace.
When this molten iron cools it forms cast iron, most is kept molten to be turned into steel.
Properties of Iron and Steel
Pig iron straight from the furnace contains impuities so is too brittle.
All the impurities removed from piig iron gives pure iron which is too soft for most uses.
Iron that is alloyed with other elements is called steel. Atoms in pure iron are aranged in layers so slide over each other easilly hence why it is so soft.
Carbon steels are iron with small amounts of Carbon, this is used for bodies of cars, knives, machinery, ships ect
Low-alloy steels are more expensive as they contain more other metals ie nickel and chromium. These are used for long span bridges and military armour plating.
High-alloy steels are even more expensive. Chromium-Nickel steels are known as stainless steel. Used for cooking utensils and cutlery. They are strong, and have great resistance to corrosion. They do not rust.
Copper, gold and aluminium are all alloyed with other metals to make them more useful.
Copper can be alloyed to make bronze and brass, both more useful.
Gold and Aluminium are made harder by adding other elements. Alloying gold is useful for jewellery. Alloyed aluminium can be used for aircraft and military vehicles.
Smart alloys are also called shape memory alloys. When deformed they return to their original shape on heating. They can be used in medicine and dentistry.
The tansition metals are found in the middle block of the periodic table.
Transition metals have properties that make them useful for building.
Copper is a very useful transition metal because of its high conductivity of electricity and heat, it is useful for pipes and wires.
There are two ways of extracting copper, by using sulfuric acid to produce copper sulfate solution. Also by smelting, which involves heating copper at high temperatures to make crude copper. Impure copper is then used as anodes in electrolysis cells to make pure copper.
This uses a lot of energy and is expensive.
Aluminium and Titanium
Aluminium and Titanium are useful as they resist corrosion
Aluminium and titanium are expensive because extracting them from their ores requires large amounts of energy.
Aluminium is very light for a metal, it is an excellent conductor of heat and electricity .
Titanium is very strong and very resistant. it has a very high melting point
Recycling aluminium is important because we need to use much less energy to produce 1kg of recycled aluminium than we use to extract 1kg of aluminium from its ore.