The document discusses the properties and extraction of sodium and its compounds. It describes that sodium is extracted through electrolysis of molten sodium chloride using the Downs process. Sodium reacts violently with water and acids, forming sodium hydroxide and hydrogen gas. Sodium hydroxide and sodium carbonate are important industrial compounds used to make paper, soap and glass.

1. 10.2 Alkali Metals
10.2.1 General characteristics of alkali metals
10.2.2 Sodium [extraction from Down's process,
properties (action with Oxygen, water, acids
nonmetals and ammonia) and uses]
10.2.3 Properties (precipitation reaction and action
with carbon monooxide) and uses of sodium
hydroxide
10.2.4 Properties (action with CO2, SO2, water,
precipitation reactions) and uses of sodium
carbonate

2. Introduction:
The element of group I(A) of the periodic table
namely,
3Lithium (Li)
11Sodium (Na)
19Potassium (K)
37Rubidium (Rb)
55Cesium (Cs)
87Francium (Fr) are called alkali metals.

4. Introduction:
These metals are called alkali metal because
they react with water to form strong alkalis. For
example,
2Na + 2H2O 2NaOH + H2

5. General characteristics of alkali metals;
• Alkali metals are highly reactive. Therefore they
are not found free in nature.
• They have strong affinity for oxygen as a result
they tarnish in moist air.
• They are obtained through the process of
electrolysis.
• They give characterstic colour in flame test
Lithium -crimson red
Sodium -Golden yellow
K, Rb, Cs -Violet

6. 11Sodium (Na)
Occurrence
It occurs as,
sodium chloride (NaCl); Found as rock salt and
also found in sea water.
Sodium nitrate (NaNO3); known as Caliche
Borax (Na2B4O7 10H2O)

7. Extraction of sodium
Difficulties in extraction of sodium:
• NaCl melts at 820℃ and its difficult to
maintain this temperature throughout the
process.
• The boiling point of sodium (883℃) near the
melting point of NaCl. In such case sodium
metal may vaporize.
• Na and Cl obtained are highly reactive and
may corrode the cell material at high
temperature.

8. Extraction of sodium from Down’s process:
The modern method for the extraction of
sodium is Down’s process.
Principle:
In this process sodium is obtained by
electrolysis of molten sodium chloride. To
overcome the difficulties in the extraction
of sodium, Down mixed NaCl with CaCl2.

9. Extraction of sodium from Down’s process:
On mixing NaCl with CaCl2 in 2:3 ratio, the
melting point lowers to 600℃. At this
temperature, Na-metal and Cl2 gas do not
corrode the cell and sodium does not
vaporize.

10. Working:
The electrolytic cell used in this process is
down cell which is a cylindrical steel vessel
lined with fire bricks as shown in figure.
Anode is graphite at the center of the cell
arising from the bottom and cylindrical
iron cathode surrounds the anode. Two
electrodes are separated by iron wire
gauge which keeps the product of
electrolysis separated.

11. Working:
On passing electricity through molten
electrolyte, sodium is discharged at
cathode which is lighter than molten
sodium chloride, rises up and collected in
a vessel containing kerosene. At anode, Cl2
is liberated and escapes through the
outlet tube.

12. Working:
Reactions:
NaCl CaCl2, 600℃ Na+ + Cl-
On passing electricity,
At cathode, 2Na+ + 2e- 2Na(Reduction)
At anode, 2Cl- Cl2 + 2e- (Oxidation)

14. Advantages of down’s process:
• Sodium is obtained in highly pure
form (99.8%).
• Cl2 is obtained as a valuable by-
product.
• Unrefined common salt can be
used.
• It is economical process.

17. Properties of sodium:
1. Action with air:
a. Fresh sodium metal is silvery white but
tarnished in air due to the formation of
a oxide layer.
4Na + O2 2Na2O
This oxide absorbs moisture and form
hydroxide.
Na2O + H2O 2NaOH

18. Thus formed hydroxide absorbs CO2 from
air to form sodium carbonate.
2NaOH + CO2 Na2CO3 + H2O
Therefore, sodium is stored in kerosene.
Fresh Tarnished

19. Properties of sodium:
1. Action with air:
b. When sodium is heated in air, it burns
with golden yellow flame forming
oxides.
4Na + O2 2Na2O
Sodium oxide
2Na + O2 Na2O2
Sodium peroxide

20. Sodium metal burning with golden yellow flame

22. Properties of sodium:
2. Action with water:
Sodium metal react with water forming
sodium hydroxide evolving H2 gas.
2Na + 2H2O 2NaOH + H2 + Heat
The reaction is highly exothermic so that
hydrogen which is a flammable gas can
catch fire or explodes.

23. Properties of sodium:
3. Action with acid:
Sodium metal reacts violently with acid
forming H2 gas.
2Na + 2HCl 2NaCl + H2
2Na + H2SO4 Na2SO4 + H2

24. Properties of sodium:
4. Action with nonmetals:
Sodium metal reacts with halogens,
sulphur and phosphorous forming
halides, sulphides and phosphide
respectively.
2Na + X2 2NaX (X=Cl, Br, I, F)
2Na + S Na2S
3Na + P Na3P

25. Properties of sodium:
5. Action with ammonia:
When sodium metal is heated with
ammonia, sodium amide is formed with
the evolution of H2 gas.
2Na + 2NH3(g) 2NaNH2 + H2
Sodamide

26. Uses of sodium metal:
• It is used in sodium vapour lamps.
• It is used as a reducing agents.
• It is used in the detection of sulphur,
nitrogen and halogens in organic
compound.
• It is also used in the extraction of boron
and silicon.
• It is also used for the production of
artificial rubber, drugs, perfumes.

27. Compounds of sodium:
1. Sodium hydroxide (NaOH):
Caustic soda or sodium hydroxide is
widely used chemical in laboratory and
for industrial purpose.

28. Properties of sodium hydroxide:
• Precipitation reaction:
NaOH precipitates hydroxides of metals
from their salt solution. NaOH act as
precipitant.
CuSO4 + 2NaOH Cu(OH)2 ↓ + Na2SO4
Bluish white ppt
FeSO4 + 2NaOH Fe(OH)2 ↓ + Na2SO4
Dirty green ppt
FeCl3 + 3NaOH Fe(OH)3 ↓ + 3NaCl
Reddish brown ppt

29. Properties of sodium hydroxide:
• Action with CO:
NaOH reacts with CO at high temperature
and pressure to give sodium salt of formic
acid which on acidification gives formic
acid.
NaOH + CO 200℃ , 10𝑎𝑡𝑚 HCOONa
sodium formate
HCOONa + H2SO4 HCOOH + NaHSO4
formic acid

30. Uses of sodium hydroxide:
• It is used in the manufacture of paper,
soap, detergetns.
• It is used as a cleansing agent.
• It is used in the extraction of aluminium
metal.
• It is used in the refining of petroleum.
• It is also used as a laboratory reagent.

31. Compounds of sodium:
2. Sodium carbonate:
Sodium carbonate occurs as anhydrous
form, Na2CO3 which is called soda ash.
Its decahydrate form Na2CO3.10H2O is
known as washing soda.

32. Properties of sodium sodium carbonate:
• Action with CO2:
When CO2 gas is passed through the
aqueous solution of Na2CO3, Sodium
bicarbonate is obtained.
Na2CO3 + H2O + CO2 2NaHCO3
Sodium bicarbonate

33. Properties of sodium sodium carbonate:
• Action with SO2:
When SO2 is passed into aqueous solution
of Na2CO3, Sodium bisulphite is formed.
Na2CO3 + H2O + 2SO2 2NaHSO3 + CO2
Sodium bisulphite

34. Properties of sodium sodium carbonate:
• Action with H2O:
It is soluble in water forming sodium
hydroxide and carbonic acid. The resulting
solution is alkaline.
Na2CO3 + H2O 2NaOH + H2CO3

35. Properties of sodium sodium carbonate:
• Precipitation reaction:
It precipitates the carbonates of metals
from their salt solution.
CaCl2 + Na2CO3 CaCO3 ↓+ 2NaCl
Calcium carbonate(white)
BaCl2 + Na2CO3 BaCO3 ↓+ 2NaCl
Barium carbonate(white)

36. Uses of sodium carbonate:
• It is used in the manufacture of glass,
borax and soap powder.
• It is used in softening of water.
• It is also used in making paper.
• It is used as washing soda for washing
clothes.
• It is also used as a laboratory reagent.

37. Some important questions;
• Give reason;
a) sodium metal gets tarnished in air.
b) Smelting process is not applied for
the extraction of alkali metals.
• Can sodium be extracted by aqueous
solution of sodium chloride? Explain
with reason.

38. Some important questions;
• Write principle and process along with the
self explanatory diagram for the extraction
of sodium by Down’s method. Why sodium
fire in laboratory not extinguished by
adding water. Mention any two advantages
of Down’s process.
• What happens when;
sodium is treated with ammonia.
CO2 passed through NaOH solution.
sodium burns in air.