Extraction Of Metals Flashcards
How are metal elements removed from sulphide ores
Ore is turned into a oxide by roasting sulphide in air forming sulphur dioxide Sulphur dioxide (which causes acid rain) is turned into sulphuric acid which is a useful product
How are metal oxides of iron, manganese and copper reduced
Carbon as coke or carbon monoxide are often used as reducing agents as they are cheap and effective - used to extract iron, manganese and copper
How are metal oxides of tungsten reduced
Hydrogen is used as the carbon can leave impurities which make the metal more brittle
What do reactions to reduce metal oxides happen in
Blast furnaces
How is iron(III) oxide reduced
Using carbon or carbon monoxide
Forms iron and carbon monoxide
In a blast furnace at temps higher than 700 degrees
How is Manganese(IV) oxide reduced
Carbon or carbon monoxide
Forms manganese and carbon dioxide
Happens in a blast furnace at temps greater than 1200 degrees
How are Copper Carbonate and Cooper(II) oxide reduced
The copper ore, CuCO3 is heated with carbon directly forming copper and carbon dioxide
Or the Carbonate is heated until it decomposes to copper(II) oxide. The oxide is then reduced using carbon
How is tungsten extracted
Reduced using hydrogen at temperatures above 700 degrees
Hydrogen more expensive than carbon but produces purer tungsten
Hydrogen highly explosive when mixed with air
Why is aluminium extracted using electrolysis
Too reactive to extract through reduction with carbon and temperatures to be reduced are very high - expensive
How is aluminium extracted using electrolysis
Ore bauxite contains impurities which are removed
Dissolved in molten cryolite, reducing melting point and reducing operating costs
Electrolyte is molten so ions are free to move
Electric current passed through electrolyte
Electrons flow from ions at the anode to the cathode
As ions loose or gain electrons, they become atoms through reduction and oxidation
What happens at the anode during electrolysis of aluminium
Positive electrode and so attracts negative ions
Oxygen ions loose electrons becoming atoms - oxidation
Oxygen looses four electrons
Anode needs replacing as carbon reacts with the oxygen formed
What happens at the cathode during electrolysis of aluminium
Negative electrode and attracts positive ions
Aluminium ions gain electrons becoming atoms (reduction)
Attracts positive aluminium ions which gain three electrons
Why can’t titanium be extracted through reduction using carbon
When reaction the ore, TiO2, with carbon, titanium carbide forms not pure titanium
How is titanium extracted
Ore is converted to titanium(IV) chloride by heating to 900 degrees with carbon is a stream of chlorine gas
Titanium chloride is purified by fractional distillation under an inert atmosphere of argon
Chlorine gets reduced in a furnace at 1000 degrees where it is heated with a more reactive metal such as Na or Mg
Leaving pure titanium and either NaCl2 or MgCl2
Why is an inert atmosphere used in the extraction of titanium
Prevents titanium chloride and titanium metal from reacting with oxygen or water vapour from the air
