Industrial manufacture of Sulphuric Acid
How is it done?
Sulphuric acid is manufactured using the CONTACT PROCESS.
In the Contact Process, the following occurs:
(i) Sulphur dioxide is made.
(ii) Suphur dioxide is converted into sulphur trioxide.
(iii) Sulphur trioxide is then converted into concentrated sulphuric acid.
In the Contact Process, the following occurs:
(i) Sulphur dioxide is made.
(ii) Suphur dioxide is converted into sulphur trioxide.
(iii) Sulphur trioxide is then converted into concentrated sulphuric acid.
Step 1
Sulphur is burnt in air.
S(s) + O2(g) -----> SO2(g)
Step 2
The sulphur dioxide produced in Step 1 is then oxidised to sulphur trioxide.
Pure dry sulphur dioxide and oxygen are heated to 450 degrees Celsius and passed over a catalyst- vanadium (V) oxide in silica gel.
2SO2(g) + O2(g) -----> 2SO3(g)
Step 3
Sulphur trioxide is hydrated indirectly by initially dissolving in concentrated sulphuric acid. Oleum is formed and is diluted to give concentrated sulphuric acid.
SO3(g) + H2SO4 ------> H2S2O7(aq)
Oleum
H2S2O7(aq) + H2O(l) -----> 2H2SO4(aq)
NB: Direct dissolving of sulphur trioxide in water is NOT practiced since the reaction is TOO EXOTHERMIC. It is extremely hazardous and difficult to control.
Sulphur is burnt in air.
S(s) + O2(g) -----> SO2(g)
Step 2
The sulphur dioxide produced in Step 1 is then oxidised to sulphur trioxide.
Pure dry sulphur dioxide and oxygen are heated to 450 degrees Celsius and passed over a catalyst- vanadium (V) oxide in silica gel.
2SO2(g) + O2(g) -----> 2SO3(g)
Step 3
Sulphur trioxide is hydrated indirectly by initially dissolving in concentrated sulphuric acid. Oleum is formed and is diluted to give concentrated sulphuric acid.
SO3(g) + H2SO4 ------> H2S2O7(aq)
Oleum
H2S2O7(aq) + H2O(l) -----> 2H2SO4(aq)
NB: Direct dissolving of sulphur trioxide in water is NOT practiced since the reaction is TOO EXOTHERMIC. It is extremely hazardous and difficult to control.
Physical Properties of Sulphuric acidConcentrated sulphuric acid is:
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Chemical Properties of Sulphuric acidDilute sulphuric acid reacts with metals, carbonates, bases and hydrogencarbonates.
These reactions are classified as REDOX reaction where sulphuric acid is the OXIDISING AGENT. Hot concentrated sulphuric acid is a powerful oxidising agent. It can oxidise metals, non-metals and their compounds where it is itself reduced to sulphur dioxide. Cu(s) + 2 H2SO4(aq) => CuSO4(aq) + SO2*g) + 2 H2O(g) Cold concentrated sulphuric acid is a powerful dehydrating agent. |