IGCSE Manufacturing chemicals Notes

Manufacturing Chemicals

This manufacturing chemicals topic covers how some important chemicals are produced in the chemical industries. This post is going to cover the production of some important inorganic chemicals such as ammonia, sodium hydroxide, and sulfuric acid. This will only cover the chemicals which are included in the IGCSE chemistry syllabus.

Process and reactions of Manufacture of ammonia:

Name of process: Haber process

Raw materials used: nitrogen (obtained from air, 78% of air is nitrogen)

 Hydrogen gas (obtained from natural gas or methane)

Conditions used:   

Temperature in degree celsius: 450◦ C

Pressure in atm: 200 atm

Catalyst used: iron

Equation for reaction : N(g) + 3H(g) ⇆ 2NH(g)

Some important uses of ammonia:

  1. Used to  make fertilizers
  2. Used make nitric acid
  3. Ammonia is used in the production of nylon
  • Why high temperature utilized despite the fact that the forward reaction is exothermic?

In order to have a higher rate of reaction, because a lower temperature would lead to a low rate of reaction. But not too high temperature is used as that would decrease the yield of ammonia.

  • Why is a high pressure used in this process?

Because there is less number of molecules of gases on the right-hand side, increasing the pressure pushes the equilibrium position to the right-hand side, hence a greater yield of ammonia.

  • Why not a very high pressure used?

It would become very expensive because using high pressure requires high energy and also  stronger structures are required.


Manufacturer of sulfuric acid

This involves three main steps

Name of process: contact process


Step1:  Sulfur is burned in air to produce the sulfur dioxide gas.

S(g) + O2(g) → SO2(g)

Another way to produce sulfer dioxide

Burning pyrite (Iron Sulfide)

4FeS2(s) +11O2(g)→2Fe2O3(s)+8SO2(g)


Step2: The Process of making sulfur trioxide

Conditions used

Temperature: 450◦C

                          Pressure: 1-2 atm

Catalyst: V2O5( Vanadium(V)Oxide)

Equation: 2SO2(g)+O2(g) ⇆ 2SO3(g)


Step3: Process of making Sulfuric acid

Reacting sulfur trioxide gas with water is too exothermic and violent.

Due to this reason, sulfur trioxide gas is firstly dissolved in concentrated sulfuric acid to form oleum or also known as fuming sulfuric acid finally oleum is converted to sulfuric acid by careful addition of water.

Equation: H2SO4(l) + SO3(g) → H2S2O7(l)


                        H2S2O7(l) +H2O(l)→2H2SO4(l)

Twice as much as sulfuric acid produced in this way when compared with the original amout used to produce oleum.

Some important uses of sulfuric acid:

  • It is used to make fertilizers such as ammonium sulfate and superphosphate.
  • In the manufacture of detergents and paints


Chlor-alkali industry: Manufacture of chlorine, hydrogen and sodium hydroxide


Process: by the electrolysis of concentrated sodium chloride solution

Electrodes used: titanium as anode along with steel as cathode

Products which are obtained: NaOH (Sodium hydroxide), hydrogen, chlorine

Some important uses of sodium hydroxide:

  • It is used in the purification of bauxite(ore of aluminum)
  • For making papers
  • Soap manufacturing
  • Making chemicals such as bleach ( 2NaOH(aq) + Cl2(g)→NaCl(aq)+NaOCl(aq)+H2O(l) )

Some of the uses of Chlorine:

  • Sterilizing water or simply kill harmful microorganisms in water
  • Used to make hydrochloric acid
  • It is also used to make bleach

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