industrial processes Flashcards
what is another name for aluminium oxide and what is its formula ?
bauxite and al203
what do we add to aluminium oxide to lower the melting point
cryolite
what temperature does the electrolysis of aluminium oxide take place ?
850-950 degrees
in the electrolysis of aluminium oxide what goes to the anode and what goes to the cathode
aluminium - cathode
oxygen -anode
what are the anodes made out of in the electrolysis of aluminium
graphite
why must the anodes be regularly replaced in the electrolysis of aluminium
because the oxygen being released reacts with the graphite to for carbon dioxide
what are the characteristics and uses
of aluminium
- light weight , resistant to corrosion due to oxide layer, strong when alloyed
- drinks can , foil , electricity cables
how do you extract aluminium from aluminium oxide
electrolysis
what is the use of a blast furnace
to extract iron from iron ore ( iron oxide / haematite)
what raw materials are used in a blast furnace ?
- coke (carbon )
- iron ore ( iron oxide )
- limestone
- hot air
step by step of the reactions in the blast furnace
1) oxygen reacts with the carbon to form co2
2) the hot co2 reacts with more carbon to form carbon monoxide which is a reducing agent
3)the co reacts with the haematite leaving the products , iron and carbon dioxide
4) the limestone ( caco3 ) decomposes to form caco and carbon dioxide
the caco reacts with silicon dioxide to form slag
why is the reaction of carbon and oxygen to form carbon dioxide so important in the blast furnace ?
its exothermic and gives energy to the reaction
what temperature is the hot air blasted in the blast furnace
1800 degrees
what kind of iron comes out
of the blast furnace ?
pig iron - it has carbon impurities
what does the haber process produce ?
Ammonia
whats the chemical formula of
ammonia
nh3
what temperature is needed for the haber process and why
450 degrees which is quite low for an industrial process , its low enough that the equilibria is shifted to a high ammonia yield but not too low to give a slow rate of reaction
what pressure is required for the haber process and why ?
200 atm , high pressure as there are less molecules on the right hand side than left hand side meaning the reaction shifts to a higher yield of
ammonia
what catalyst is required for the haber process
an iron catalyst
what is the equilibria reaction in the haber process and what kind of reaction is this
n2 + 3h2 2NH3
its exo thermic
what are the uses of ammonia ?
fertilisers
nitric acid
making nylon
what does the contact process produce ?
sulphuric acid
what are the raw materials in the contacts process v
sulphur and air
what are the steps of the contact process and which reaction is the equilibrium reaction
1)make sulphur dioxide •burn sulphur in air •heat sulphide ore in air 1)make sulphur trioxide -equilibria •2so2 + o2 2so3 •its an exothermic reaction •conditions: -vanadium catalyst -2 atm high pressure -450temp -excess oxygen 3)make it acidic •dissolve sulphur trioxide in a little bit of sulphuric acid •then add water
in the contact process why dont we just add water to sulphur trioxide
because it forms sulphuric acid steam and is very dangerous
in the contact process what is the name
of the product when we dissolve so3 in suphuric acid
oleum or fuming sulphuric acid
what is sulphuric acid used for ?
- making fertilisers
- making detergents
- making paint
