Carbon and its compounds (Solvay process)

Sodium carbonate and sodium hydrogen carbonate

The raw materials are
Sodium chloride, Calcium carbonate, Coal or coke, Ammonia

In the first stage ammonia gas is mixed with brine (concentrated sodium chloride solution) forming ammoniated brine

Ammoniated brine is then pumped from the top of the second tower called carbonator and is allowed to trickle down slowly, while carbon (IV) oxide from a kiln is pumped in at the base

Sodium hydrogen carbonate and ammonium chloride are the products
NH3 (g) + CO2 (g) → NH4HCO3 (aq)

NH4CO3 (aq) + NaCl (aq) → NaHCO3 (s) + NH4Cl (aq)
Sodium hydrogen carbonate is less soluble and forms a precipitate while ammonium chloride remains in aqueous form

Sodium hydrogen carbonate is filtered and dried

For production of sodium carbonate sodium hydrogen carbonate is decomposed by heating
2NaHCO3 (s) → Na2CO3 (s) + CO2 (g) + H2O (l)
The carbon (IV) oxide produced is recycled

The carbon (IV) oxide used mainly comes from heating of limestone with coke
C (s) + O2 (g) → CO2 (g)

CaCO3 (s) → CaO (s) + CO2 (g)
CaO produced is added to little water and slaked with the filtrate from the carbonator (ammonium chloride) where it produce ammonia gas when heated which is then recycled
CaO (s) + H2O (l) → Ca (OH) 2 (s)

Ca (OH) 2 (s) + 2NH4Cl (aq) → CaCl2 (aq) + 2NH3 (g) + 2H2O (l)
The filtrate can also be used to obtain crystals of ammonium chloride used in manufacture of dry cells

The only by product not used in this process is calcium chloride hence this process is said to be very efficient

The plant should be located near a river or a lake since a lot of water is required to cool the carbonator since the reactions that take place there are exothermic

Solvay process

Uses of sodium carbonate

Manufacture of glass
Softening of hard water
In paper industry

Uses of sodium hydrogen carbonate

Used as anti-acid for stomach upsets
Used in baking powder
Used in soft drinks

Please visit the links below for


carbon (IV) oxide

carbon (II) oxide

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