Chemical Industries II – SS1 Chemistry Lesson Note (Third Term)

A chemical industry is a factory that changes raw materials into useful chemical products.

Behavioural objectives

By the end of the lesson, students should be able to:

1. state the four groups into which chemical industries are divided by their products;
2. distinguish between heavy chemicals and fine chemicals and give examples of each;
3. list five types of chemical industry;
4. state the main products and uses of the fertiliser, paint, cement, plastic and pharmaceutical industries;
5. name the major raw material of the plastic industry.

How are chemical industries divided?

Chemical industries are divided into four groups according to their products.

• Basic chemicals: acids, alkalis, salt and organic chemicals.
• Materials for artificial fibres and plastics: chemical products used to make artificial fibres and plastics.
• Starting materials for other industries: chemicals used by industries that make paints, fertilisers and explosives.
• Products for personal use: cosmetics, drugs and soap.

What are heavy and fine chemicals?

Heavy chemicals are made in large quantities, while fine chemicals are made in small quantities and are purer.

What are heavy chemicals?

Heavy chemicals are chemicals needed in large quantities by many chemical industries all over the world.

• Acids: tetraoxosulphate(VI) acid (the most important), hydrochloric acid and trioxonitrate(V) acid.
• Alkalis and lime products: caustic soda (sodium hydroxide), calcium trioxocarbonate(IV) and slaked lime, Ca(OH)₂.
• Special derivatives: caustic potash, sodium trioxocarbonate(IV) and bleaching powder, CaOCl₂.
• Metals: iron, copper, tin, aluminium and zinc.
• Organic materials: coke, coal tar, benzene and methylbenzene.
• Ammonia, NH₃: made in large quantities and used to make fertilisers and explosives.

What are fine chemicals?

Fine chemicals are chemicals made in small quantities and with a high degree of purity.

• Drugs: medicines need pure ingredients.
• Analytical chemicals: used for testing and measuring in laboratories.
• Laboratory reagents: pure chemicals used in experiments.
• Photographic materials: chemicals used in making and developing photographs.
• Cost: they are purer than heavy chemicals, so they are more expensive.

What is the difference between heavy and fine chemicals?

What are the main types of chemical industry?

There are five main types of chemical industry: fertiliser, paint, cement, plastic and pharmaceutical.

Many chemical industries exist because of the different raw materials found in nature.

What is the fertiliser industry?

The fertiliser industry makes chemicals that help crops to grow and protect them from pests.

• Fertilisers: ammonium nitrate, NH₄NO₃; ammonium sulphate, (NH₄)₂SO₄; and urea.
• Pesticides and insecticides: kill pests that damage crops.
• Herbicides: kill weeds.
• Fungicides and germicides: kill fungi and germs.
• Source: these products come from the petrochemical industry and help agricultural production.

What is the paint industry?

Paint is a fluid mixture which contains suspended colouring materials.

• Pigment: the colouring material in the paint.
• Binder: holds the pigment to the surface after drying.
• Solvent (thinner): keeps the paint fluid so that it can be spread.
• Decoration: paint gives walls and furniture colour.
• Protection: paint guards surfaces against weathering and corrosion, for example iron gates and roofing sheets.

What is the cement industry?

Cement is a grey powder made by heating a mixture of limestone and clay.

1. Limestone and clay are crushed and mixed.
2. The mixture is heated strongly in a kiln.
3. The product is cooled and ground into a fine powder.
4. A little gypsum is added to control how fast the cement sets.

• Mortar: cement mixed with sand and water, used to fasten stones and bricks together.
• Setting: the mortar hardens like stone.

What is the plastic industry?

The plastic industry makes plastic goods from raw materials obtained from crude oil (petroleum).

• Bags: the first of the four categories of plastic goods.
• Household items: the second category.
• Industrial plastics: casings for radios, cassette recorders and TV sets, and PVC pipes and fittings for building.
• Miscellaneous items: other plastic goods that fit none of the first three categories.
• Raw materials: the starting materials are obtained by fractional distillation of crude oil.
• Major raw material: ethene.

What is the pharmaceutical industry?

The pharmaceutical industry makes drugs and other materials used in medicine.

• Plant extracts: many are known to have medical properties.
• Organic compounds: most medicines are organic compounds.
• Inorganic substances: some are still used in pharmacy, as in the table below.

• Quinine: a drug used to treat malaria.
• Insulin: a drug used to treat diabetes.
• Petrochemical products: many synthetic drugs, syringes and surgical materials are made from them.
• Other products: disinfectants, cosmetics, detergents and soap also come from petrochemicals.

Evaluation

1. State the four groups into which chemical industries are divided by their products.
2. Why are some chemicals called heavy chemicals?
3. Give two differences between heavy chemicals and fine chemicals.
4. State two uses of paint.
5. What is the major raw material of the plastic industry, and how are the starting raw materials for plastics obtained?

Assignment

1. (a) What is a chemical industry?
   (b) Mention three types of chemical industry.
   (c) Give one example of (i) a heavy chemical, (ii) a fine chemical.
   (d) Name the raw materials used to make cement.