The document details the Solvay process for producing sodium carbonate, highlighting key raw materials like limestone, ammonia, and sodium chloride. It outlines the basic reactions involved, including the purification of brine, formation of sodium hydrogen carbonate, and recovery of ammonia, along with the flow of materials and by-products. The advantages of the process include its use of inexpensive raw materials and the production of a pollution-free product.

2. INDUSTRIAL
CHEMISTRY
Chemistry
group
presentation

3. 16.6 Solvay Process
• List raw materials for the Solvay process;
• Describe the basic reactions of Solvay process;
• Develop a flow sheet diagram of Solvay process;

5. Basic reactions:
preparation of ammonical
brine
carbonation of ammonical
brine
separation of sodium
bicarbonate
preparation of carbon
dioxide
recovery of ammonia
Raw
materials:
limestone,
ammonia gas,
sodium
chloride
Advantages:
Cheap raw material
Pollution free
Pure product
Low consumption
of fuel
Solvay's process

6. Brine is concentrated by evaporation to atleast
30% Impurities such as calcium, magnesium and
iron are removed by precipitation.
eg,
Ca2+
(aq) + CO3
2-
(aq) → CaCO3(s)
Mg2+
(aq) + 2OH-
(aq) → Mg(OH)2(s)
Fe3+
(aq) + 3OH-
(aq) → Fe(OH)3(s)
Brine solution is then filtered and passed through
an ammonia tower to dissolve ammonia. This
process is exothermic, releases energy, so the
ammonia tower is cooled.
Brine Purification

7. Sodium Hydrogen Carbonate Formation
Carbon dioixide is produced by the thermal decomposition of limestone,
CaCO3(s), in the lime kiln:
CaCO3(s) → CO2(g) + CaO(s)
Carbon dioxide is bubbled through the ammoniated brine solution in the
carbonating tower. The carbon dioxide dissolves to form a weak acid;
CO2(g) + H2O(l) → HCO3
-
(aq) + H+
(aq)
The ammonia in the brine reacts with H+ to form ammonium ions:
NH3(aq) + H+
(aq) → NH4
+
(aq)
The HCO3
- then reacts with the Na+ to form a suspension of sodium hydrogen
carbonate:
HCO3
-
(aq) + Na+
(aq) → NaHCO3(s)
NaHCOprecipitates because of the large excess of Na+ present in the brine
which forces the equilibrium position to shift to the right by Le Chatelier's
Principle (NaHCO3 is quite soluble in water). The overall molecular equation
for the formation of sodium hydrogen carbonate in the carbonating tower is:
NH3(aq) + CO2(g) + NaCl(aq) + H2O(l) → NaHCO3(s) + NH4Cl(aq)net ionic equation
for the formation of sodium hydrogen carbonate in the carbonating tower is:
NH3(aq) + CO2(g) + Na+
(aq) + H2O(l) → NaHCO3(s) + NH4
+
(aq)
where Cl- is a spectator ion

8. Sodium Carbonate Formation
Suspended sodium hydrogen carbonate is
removed from the carbonating tower and
heated at 300oC to produce sodium
carbonate:
2NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(g)
The carbon dioxide produced is recycled
back into the carbonating tower.

9. Ammonia Recovery
CaO is formed as a by-product of the thermal
decomposition of limestone in the lime kiln. This
CaO enters a lime slacker to react with water to
form calcium hydrooxide
CaO(s) + H2O(l) → Ca(OH)2(aq)
The calcium hydroxide produced here is reacted
with the ammonium chloride separated out of the
carbonating tower by filtration:
Ca(OH)2(aq) + 2NH4Cl(aq) → CaCl2(aq) + 2H2O(l) +
2NH3(g)
The ammonia is recycled back into the process to
form ammoniated brine. Calcium chloride is
formed as a by-product of the Solvay Process.

13. Key concepts
• Sodium carbonate, na2co3, has a number of uses but its
most common use is in the production of glass.
• Since the 1860's, sodium carbonate has been produced
using the Solvay process.
• The Solvay process is a continuous process using
limestone (caco3) to produce carbon dioxide (co2) which
reacts with ammonia (nh3) dissolved in brine
(concentrated nacl(aq)) to produce sodium carbonate.
• The steps in the Solvay process are:
1. Brine purification
2. Sodium hydrogen carbonate formation
3. Sodium carbonate formation
4. Ammonia recovery

14. Q/A
• Raw materials for Solvay process includes
1. ammonia
2. brine
3. lime stone
4. all of above
• Solvay process is used to make
1. potassium carbonate
2. sodium carbonate
3. NaCl
4. NaOH
• Another name for sodium carbonate is …
1. soda ash
2. lye
3. washing soda.
4. caustic soda.

15. • What is currently the major use of sodium carbonate?
1. Glass-making
2. Soap-making
3. Water-softening
4. Ink removal from paper
• Calcium carbonate is also known as …
1. lime
2. Limestone
3. soda ash
4. washing soda
• How is brine purified before being used in the Solvay process?
1. Filtration
2. Fractional crystallization
3. Distillation
4. Centrifuging.

16.  Why only NaHCO3 precipitates , when
CO2 is passed through the ammonical
brine?
 Which raw materials are required for
the formation of sodium carbonate?
 How is CO2 prepared in the Solvay
process?
 Give the reaction of formation of
ammonia in the process
 Give the advantages of Solvay's
process