2. Ammonia: Introduction
Compound of nitrogen and hydrogen with a formula of
NH3
Ammonia is found in trace quantities in the
atmosphere, being produced from the putrefaction
(decay process) of nitrogenous animals and vegetable
matters
one of the most highly produced inorganic chemicals
3. Ammonia: Reactions and Equilibrium
The commercial production of ammonia by the
direct combination of nitrogen and hydrogen is an
example of equilibrium in the gaseous state
Low temperatures is better because more
ammonia is obtained at equilibrium
While a low temperature favors a high equilibrium
yield of ammonia, it also dictates that a long time
will be required to obtain the yield
4. Ammonia: Rate and Catalysis of the Reaction
A great asset in the production of ammonia is a catalyst
which speeds the reaction between nitrogen and hydrogen
Early in this century, a German academic chemist, Fritz
Haber, and an industrial colleague, Carl Bosch, found that a
mixture of Fe2O3 and Fe3O4 catalyzes this reaction at
temperatures in the range of 400 degree Celsius to 600
degree Celsius
The Haber- Bosch process continues to be the most
common method for making ammonia. The nitrogen is
obtained from liquefied air, and the hydrogen is usually from
natural gas decomposed by heating.
5. Ammonia: Manufacturing Procedures
Ammonia is produced in a process known as the Haber
process, in which nitrogen and hydrogen react in the
presence of an iron catalyst to form ammonia
The hydrogen is formed by reacting natural gas and
steam at high temperatures and the nitrogen is
supplied from the air
Other gases (such as water and carbon dioxide) are
removed from the gas stream and the nitrogen and
hydrogen passed over an iron catalyst at high
temperature and pressure to form the ammonia.
6. Ammonia: Uses and Economics
Used in the production of liquid fertilizer solutions
which consist of ammonia, ammonium nitrate, urea and
aqua ammonia. It is also used by the fertilizer industry
to produce ammonium and nitrate salt
Dissociated ammonia is used in such metal treating
operation as nitriding, carbonitriding, bright annealing,
furnace brazing, sintering, sodium hydride descaling,
atomic hydrogen welding and other applications where
protective atmospheres are required
7. Ammonia: Uses and Economics
Used in manufacture of nitric acid; certain alkalies such
as soda ash; dyes; pharmaceuticals such as sulfa
drugs, vitamins and cosmetics; synthetic textile fibers
such as nylon, rayon and acrylics; and for the
manufacture of certain plastics such as phenolics and
polyurethanes.
Ammonia is used as the developing agent in
photochemical processes such as white printing, blue
printing and in the diazo duplication process.
8. Ammonia: Uses and Economics
Weak ammonia solutions are also widely used as
commercial and household cleaners and detergents
Used in the rubber industry for the stabilization of natural
and synthetic latex to prevent premature coagulation
The decomposition of ammonia serves as a source of
hydrogen for some fuel cell and other applications
Pulp and paper industry uses ammonia for pulping wood
and as a casein dispersant in the coating of paper
10. Physical Properties
•Appearance: A white crystalline •Boiling point: 1390C (2534F)
substance (solid)
•Melting point: 318C (604F)
•Smell: Odourless
•Density: 2.13g/cm^3
•Transparent: Only in liquid form
•Flammable: No
•Poisonous: Yes
(causes burns when inhaled)
•Molecular Weight: 39.997g/mol
11. Chemical Properties
•Acidity: 13-14 pH (basic) •Solubility in Water: 1110g/L (20C)
•Basic Type: Caustic Metallic Base •Soluble: in water, acids and alcohol
•Corrosive: High
•Reactivity: Medium
•Hygroscopic: Yes
(absorbs CO2 and moisture from air)
12. Neutralization
•The hydroxide ion makes sodium •Sodium hydroxide reacting with an acid
hydroxide a very strong base which will generally result in a neutralisation
react with any acid which will process
neutralise each other.
•For instance, sodium hydroxide reacts
•In general, neutralisation reactions with hydrochloride acid:
can be represented as follows in an NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)
ionic equation:
OH−(aq) + H+(aq) → H2O(l)
13. Manufacture
The major method for producing sodium hydroxide is
electrolysis of concentrated brine (sodium chloride solution)
produces chloride gas, hydrogen gas and sodium hydroxide.
2NaCl(aq) + 2H2O(l) -----> H2(g) + Cl2(g) + 2NaOH(aq)
At the anode (positive electrode), the chloride ions (Cl-) are
oxidised to chloride gas (Cl2(g)). At the cathode (negative
electrode), the sodium ions (Na+) and water (H2O(l)) are
reduced to hydrogen gas (H2(g)) and sodium hydroxide
(NaOH(aq)).
14. At the anode, titanium is the metal and
The mercury cell process chloride ions are oxidised to chloride
(Castner-Kellner) gas:
2Cl-(aq) -----> Cl2(g) + 2e-
At the cathode, mercury is flowing
along the bottom of the cell. Sodium
ions are reduced to sodium metal:
Na+(aq) + e- -----> Na(s)
An amalgam is formed when sodium
metal dissolves in the liquid mercury
and it is removed to the decomposer.
The amalgam then reacts with water to
form sodium hydroxide, hydrogen gas
and mercury:
2Na/Hg(l) + 2H2O(l) -----> 2NaOH(aq) +
H2(g) + 2Hg(l)
15. The saturated brine flows
through the diaphragm and into
Nelson diaphragm cell process the cathode compartment.
At the anode, carbon or
titanium coated with Ru-Ti, the
chlorine ions are oxidized.
At the cathode, steel mesh,
hydrogen gas and hydroxide are
produced:
2H2O(l) + 2e -----> H2(g) + 2OH-(aq)
The diaphragm allows the
sodium ions to migrate across it
and to combine with hydroxide,
forming sodium hydroxide:
2H2O(l) + 2Cl-(aq) + 2Na+(aq) ----->
2NaOH(aq) + H2(g) + Cl2(g)
Solid sodium hydroxide can be
crystallised out.
16. Membrane cell process At the anode, titanium is the metal.
At the cathode the metal is nickel
and water is reduced:
2H2O(l) + 2e -----> H2(g) + 2OH-(aq)
Sodium ions migrate across the
membrane and combine with
hydroxide to form sodium
hydroxide in the cathode
compartment:
2H2O(l) + 2Cl-(aq) + 2Na+(aq) ----->
2NaOH(aq) + H2(g) + Cl2(g)
17. Soap making:
The common fats, triglyceride esters
react with sodium hydroxide to form
glycerol and the sodium salt of the
fatty acid which is soap.
The reaction between a strong base
and a fat is called ‘saponification’,
can be presented by the equation
The equation can be simplified to:
C18H36O2 + NaOH -> alcohol + salt of the carboxylic acid (soap)
18. Cleaning agent:
•Sodium hydroxide is usually added to •The industrial oil does not
hot water and then can be used to react easily, so it needs energy
dissolve fat, grease, oil and protein to break it up to react.
based deposits.
•The hot water provides the
•Sodium hydroxide solution is widely energy required to make the
used in cleaning the oil which is used sodium hydroxide work
in making metal products. efficiently.
•Compared to CFC
(chlorofluorocarbon, a powerful
substance to clean the oil), it does
not pollute the environment.
19. Aluminum production:
•Aluminium ore is usually contained in
the mineral bauxite that is a mixture
of hydrated aluminium oxides Al2O3
and hydrated iron oxides, Fe2O3.
•In aluminum refining, sodium
hydroxide will only react with
aluminium oxide and form sodium
The ionic equation will be:
aluminates (red mud), NaAl(OH)4
Al2O3(s) + 2 OH−(aq) + 3 H2O(l) → 2
[Al(OH)4] (aq)−
•After that, aluminum oxide will
precipitate then be washed and
The equation with NaOH:
heated to form pure aluminum.
Al2O3(s) + 3H2O(l) + 2NaOH(aq) ----->
2NaAl(OH)4(aq)
20. Paper pulp industry:
•In the process of paper making, there
are two main parts: pulping and
papermaking.
•There are always some excess chemicals
used to pulp the paper, sodium
hydroxide will help regenerate these
chemicals to reduce the cost.
•Because of the corrosive property of
sodium hydroxide, it will also be added
to the process of bleaching to increasing
the efficiency.
•It also has a function of PH control. PH
stays at around 8 where the hypochlorite
bleach works the most efficiently.
21. Environmental and health issues
• Sodium hydroxide can cause •In the atmosphere, sodium
severe burns and damage to any hydroxide can dissolve in water
tissues of the body, because of: vapour and form aerosols or
1. The reaction of sodium hydroxide mists which are very corrosive.
with moisture generates heat
and causes thermal burns
(exothermic reaction). •Due to the neutralization of
2. The reaction of sodium hydroxide pH, sodium hydroxide allows
with organic molecules results in specific plants to grow more
chemical burns. efficiently by adjusting the
balance of nutrients
