Key terms: Manufactured Substances in Industry

This glossary defines the terms you must use precisely in this chapter. Many marks are won or lost on a single word, alloy versus compound, rate versus yield, compression versus tension, so learn each meaning and practise using it in a sentence. The terms are grouped by content standard.

Industrial processes (8.1 and 8.2)

• Contact process (proses sentuh / 接触法), the industrial process that manufactures sulfuric acid from sulfur, oxygen and water, with vanadium(V) oxide as catalyst.
• Haber process (proses Haber / 哈柏法), the industrial process that manufactures ammonia by combining nitrogen and hydrogen over an iron catalyst.
• Sulfuric acid (asid sulfurik / 硫酸), H₂SO₄, a widely used industrial acid made by the Contact process; used in fertilisers, detergents and car accumulators.
• Ammonia (ammonia / 氨), NH₃, a gas made by the Haber process; used to make nitrogenous fertilisers and nitric acid.
• Catalyst (mangkin / 催化剂), a substance that increases the rate of a reaction without being used up and without changing the yield or the position of equilibrium. V₂O₅ is used in the Contact process and iron in the Haber process.
• Reversible reaction (tindak balas berbalik / 可逆反应), a reaction that can proceed both forwards and backwards, shown by the sign ⇌; both the Contact and Haber reactions are reversible.
• Equilibrium (keseimbangan / 平衡), the state of a reversible reaction in which the forward and backward reactions occur at the same rate, so the amounts of reactants and products stay constant.
• Exothermic reaction (tindak balas eksotermik / 放热反应), a reaction that releases heat. Because the forward reactions here are exothermic, a higher temperature lowers the yield.
• Yield (hasil / 产率), the amount of product formed. It depends on the position of equilibrium, which is affected by temperature and pressure but not by a catalyst.
• Rate of reaction (kadar tindak balas / 反应速率), how fast a reaction proceeds. It is increased by a higher temperature, a higher pressure and a catalyst.
• Compromise (optimum conditions) (kompromi / 折衷条件), the conditions chosen for an industrial process to balance an acceptable rate against an acceptable yield at reasonable cost.
• Sulfur dioxide (sulfur dioksida / 二氧化硫), SO₂, made by burning sulfur in air; the starting gas of the Contact process and a cause of acid rain if released.
• Sulfur trioxide (sulfur trioksida / 三氧化硫), SO₃, formed when sulfur dioxide reacts with oxygen over the V₂O₅ catalyst; it is absorbed into concentrated sulfuric acid.
• Oleum (oleum / 发烟硫酸), H₂S₂O₇, formed when sulfur trioxide is dissolved in concentrated sulfuric acid; it is then diluted with water to give sulfuric acid.

Alloys (8.3)

• Pure metal (logam tulen / 纯金属), a metal made of identical atoms arranged in orderly layers that can slide over one another, making it soft and easily bent.
• Alloy (aloi / 合金), a mixture of two or more elements, of which the main one is a metal. It is harder than the pure metal because different-sized atoms disrupt the sliding of the layers.
• Bronze (gangsa / 青铜), an alloy of copper and tin; used for medals, statues and artwork.
• Brass (loyang / 黄铜), an alloy of copper and zinc; used for musical instruments and decorative fittings.
• Stainless steel (keluli tahan karat / 不锈钢), an alloy of iron with carbon, chromium and nickel; resists rusting, so it is used for cutlery and surgical instruments.
• Duralumin (duralumin / 杜拉铝), an alloy of aluminium with copper and magnesium; light but strong, so it is used for aircraft bodies.

Composites, glass and ceramics (8.4 and 8.5)

• Composite material (bahan komposit / 复合材料), a material made by combining two or more materials so that the product has better properties than the individual components.
• Reinforced concrete (konkrit bertetulang / 钢筋混凝土), a composite of concrete and steel bars; strong under both compression and tension, so it is used in buildings and bridges.
• Compression (mampatan / 压力), a squeezing force. Concrete is strong under compression.
• Tension (tegangan / 张力), a stretching force. Concrete is weak under tension, but steel is strong under it.
• Fibreglass (gentian kaca / 玻璃纤维), a composite of glass fibre and plastic resin; light, strong and corrosion-resistant, used for boat and car bodies.
• Fibre optic (gentian optik / 光纤), very pure glass that carries data as light over long distances with little loss.
• Silica (silika / 二氧化硅), silicon dioxide, SiO₂, the main raw material of glass.
• Soda-lime glass (kaca soda-kapur / 钠钙玻璃), glass made from silica, sodium carbonate and limestone; cheap, used for bottles, windows and light bulbs.
• Borosilicate glass (kaca borosilikat / 硼硅玻璃), glass containing boron oxide; withstands sudden temperature change, used for laboratory apparatus and cookware.
• Lead crystal glass (kaca kristal plumbum / 铅晶玻璃), glass containing lead(II) oxide; dense and sparkling, used for decorative glassware and lenses.
• Photochromic glass (kaca fotokromik / 光致变色玻璃), glass containing silver compounds that darkens in bright light and clears in dim light; used for spectacle lenses.
• Ceramic (seramik / 陶瓷), a material made from clay and hardened by firing at high temperature; hard, brittle, chemically inert, with a very high melting point, and it does not conduct electricity.
• Corrosion resistance (ketahanan kakisan / 抗腐蚀性), the ability of a material to resist being eaten away by air, water or chemicals; a reason for alloying (as in stainless steel) and for using fibreglass.

Using the glossary

Do not just read these definitions, use them. Cover the definition and say it aloud from the term, then try each term in a full sentence of your own, such as “A catalyst increases the rate but not the yield.” The words in this chapter are precise for a reason: the marking scheme expects alloy not “metal mixture”, yield not “amount that works”, and tension not “pulling”. A one-to-one teacher can quiz you on these terms and correct any loose usage, which is exactly the kind of easy mark students drop in the SPM Chemistry papers. Once the vocabulary is secure, the revision notes and practice questions for this chapter will read much more easily.