Key terms: Consumer and Industrial Chemistry

Precise wording earns marks in this chapter, so learn each term with its exact meaning. Where a term has a common Malay name, it is shown in brackets after the English so you recognise it in any medium. Use this glossary alongside the revision notes: read the definition, cover it, and say it back in your own words until it is secure.

Oils, fats and their properties

• Oil (minyak). An ester of glycerol and fatty acids that is usually liquid at room temperature, comes mainly from plants, and is unsaturated.
• Fat (lemak). An ester of glycerol and fatty acids that is usually solid at room temperature, comes mainly from animals, and is saturated.
• Fatty acid (asid lemak). A long-chain carboxylic acid that combines with glycerol to form the oils and fats known as triglycerides.
• Triglyceride (trigliserida). The triester formed from one glycerol molecule and three fatty acid molecules; the general structure of oils and fats.
• Saturated (tepu). Describes a fatty acid chain with only single carbon-to-carbon bonds; saturated fats have higher melting points and are usually solid.
• Unsaturated (tak tepu). Describes a fatty acid chain with one or more carbon-to-carbon double bonds (C=C); unsaturated oils have lower melting points and decolourise bromine water.
• Bromine water test (ujian air bromin). The test for unsaturation: an unsaturated oil decolourises bromine water in an addition reaction, while a saturated fat does not.
• Rancidity (ketengikan). The unpleasant change in fats and oils caused by oxidation, which antioxidants are added to slow down.

Soaps and detergents

• Soap (sabun). The sodium or potassium salt of a long-chain fatty acid, made by saponification of an oil or fat.
• Detergent (detergen). The sodium salt of a sulphonic acid derivative, made from petroleum; unlike soap, it does not form scum in hard water.
• Saponification (saponifikasi). The reaction in which an oil or fat is heated with a hot concentrated alkali to produce soap and glycerol.
• Glycerol (gliserol). The second product of saponification, formed alongside soap when the ester bonds in the fat are broken.
• Salting out (penggaraman keluar). Adding sodium chloride to the soap mixture to lower the solubility of the soap so it separates and floats to the surface.
• Hydrophilic head (kepala hidrofilik). The ionic end of a soap or detergent particle (–COO⁻ or –SO₃⁻) that dissolves in water.
• Hydrophobic tail (ekor hidrofobik). The long non-polar hydrocarbon end of a soap or detergent particle that dissolves in grease but not in water.

Cleaning action

• Surface tension (tegangan permukaan). The force that makes the surface of water behave like a stretched skin; soap lowers it so water can wet a greasy surface.
• Emulsion (emulsi). A mixture in which small droplets of one liquid (grease) are suspended in another (water); soap surrounds grease droplets to form an emulsion that can be rinsed away.
• Scum (kekat). The insoluble solid formed when soap reacts with the calcium and magnesium ions in hard water, wasting soap and reducing lather.
• Hard water (air liat). Water containing dissolved calcium and magnesium ions, which react with soap to form scum but do not affect detergents.
• Builder / water softener (bahan pembina / pelembut air). A detergent additive, such as sodium tripolyphosphate, that removes calcium and magnesium ions so the detergent cleans better.
• Suspension agent (agen ampaian). A detergent additive that keeps loosened dirt suspended in the water so it is not redeposited on the cloth.

Food additives

• Food additive (bahan tambah makanan). A substance added to food to improve its keeping quality, safety, taste or appearance.
• Preservative (bahan pengawet). An additive that slows the growth of microbes so food lasts longer.
• Antioxidant (antioksidan). An additive that slows oxidation, preventing fats from turning rancid and cut fruit from browning.
• Flavour enhancer (penambah perisa). An additive that strengthens or improves the taste of food, such as monosodium glutamate.
• Colouring / dye (pewarna). An additive that restores or adds colour to make food look more attractive.
• Stabiliser (penstabil). An additive that keeps a food mixture uniform and gives it the right texture, stopping ingredients from separating.

Medicines, cosmetics and modern materials

• Analgesic (analgesik). A medicine that relieves pain, such as aspirin or paracetamol.
• Antibiotic (antibiotik). A medicine that kills or stops the growth of bacteria; it does not act on viruses, and the full course must be completed to avoid resistance.
• Cosmetic (kosmetik). A substance applied to the body to clean, protect or improve appearance, such as sunscreen or shampoo.
• Composite material (bahan komposit). A material made by combining two or more materials to gain properties that neither has alone, such as fibreglass or reinforced concrete.
• Superconductor (superkonduktor). A material that conducts electricity with no resistance at very low temperatures, used in powerful magnets.
• Ceramic (seramik). A hard, heat-resistant and chemically stable material used for cutting tools, engine parts and electrical insulators.
• Nanotechnology (nanoteknologi). The technology of working with matter at the scale of nanometres, where nanoparticles have a very large surface area for their size and behave differently from bulk material.
• Nanoparticle (nanozarah). A particle at the nanometre scale whose very large surface area for its size makes it useful as an efficient catalyst and in advanced materials and medicine.

How to use this glossary

Read each definition, then cover it and restate it in your own words, checking you keep the key phrase, “sodium salt of a fatty acid”, “insoluble scum”, “same negative charge repels”. In the exam, using the exact term instead of a vague description is often the difference between a full and a partial mark, especially in the cleaning-action explanation and the compare questions. A one-to-one teacher can test you on these terms and correct any loose definitions, which is a quick way to tighten your answers across the SPM Chemistry written papers. Learn the vocabulary here first, and the revision notes, worked examples and practice questions for this chapter will all make more sense.