Glass is made by melting sand (silica, SiO2) with other substances, and comes in types such as fused silica, soda-lime, borosilicate and lead crystal glass. Ceramics are made from clay hardened by heating at high temperature.
Both are hard, brittle and chemically inert, so their properties are matched to uses such as containers, cookware, insulators and tiles.
This page covers one Form 4 content standard from the Manufactured Substances in Industry chapter: glass and ceramics. The exam asks for the raw materials, the main types of glass with their special properties and uses, the general properties of ceramics, and how the properties of each material suit it to a particular use. This is a properties-and-uses topic, so link every property to a use in your answers.
Glass: raw material and types
The main raw material of glass is sand (silica, SiO₂), which is melted with other substances and then cooled. Different additives give different types of glass, each with its own properties and uses:
- Fused (quartz) glass, almost pure silica. It has a very high melting point and can withstand sudden temperature changes, and it transmits ultraviolet light. It is used for high-temperature lenses, optical fibres and laboratory equipment.
- Soda-lime glass, silica with sodium oxide and calcium oxide. It is the cheapest and most common glass, but it softens easily on heating. It is used for windows, bottles, jars and drinking glasses.
- Borosilicate glass, silica with boron oxide. It withstands heat and sudden temperature change (thermal shock) and expands very little, so it is used for cookware and laboratory glassware.
- Lead crystal glass, silica with lead(II) oxide. It is dense, has a high refractive index and sparkles, so it is used for decorative glassware, prisms and lenses.
Ceramics: raw material and properties
Ceramics are made mainly from clay (such as kaolin), which is shaped when wet and then hardened by heating at a high temperature. Their general properties are that they are:
- hard but brittle;
- chemically inert (they do not react with most acids and alkalis);
- have a very high melting point and withstand high temperatures;
- are good electrical and heat insulators;
- strong under compression.
Uses of ceramics
Because of these properties, ceramics are used for electrical insulators, tiles and bricks, tableware and pottery, spark plugs, and heat-resistant components. In each case a property is matched to the need: their inertness suits them to tableware, their insulating ability to electrical fittings, and their heat resistance to furnace linings and tiles.
Worked example
Question. A 200 g sample of soda-lime glass is made from 150 g of silica, 30 g of sodium oxide and 20 g of calcium oxide. Calculate (a) the percentage by mass of silica and (b) the percentage by mass of calcium oxide in the glass.
Step 1, Set up the percentage for silica. Percentage by mass = (mass of component ÷ total mass) × 100.
Step 2, Calculate for silica. = (150 g ÷ 200 g) × 100 = 0.75 × 100 = 75 %.
Step 3, Calculate for calcium oxide. = (20 g ÷ 200 g) × 100 = 0.10 × 100 = 10 %.
Answer. (a) The percentage by mass of silica is 75 %. (b) The percentage by mass of calcium oxide is 10 %. (As a check, silica 75 % + sodium oxide 15 % + calcium oxide 10 % accounts for the whole sample.)
Practice question
Question. (a) State the main raw material of glass and the main raw material of ceramics. (b) Explain why borosilicate glass, rather than soda-lime glass, is used to make laboratory beakers. (c) Give one property of ceramics that makes them suitable for use as electrical insulators.
Answer. (a) The main raw material of glass is sand (silica, SiO₂); the main raw material of ceramics is clay (such as kaolin). (b) Borosilicate glass withstands heat and sudden temperature change (thermal shock) and expands very little, so it does not crack when heated strongly, whereas soda-lime glass would crack; this makes borosilicate suitable for beakers that are heated. (c) Ceramics are good electrical insulators (they do not conduct electricity), so they are suitable for electrical insulators.
Exam tip
The examiner wants you to connect a property to a use, not just list properties. For glass, learn one distinctive property and use for each type: fused silica for high temperatures, soda-lime for cheap everyday containers, borosilicate for cookware and lab glassware, lead crystal for decorative and optical items. For ceramics, remember the cluster hard, brittle, inert, heat-resistant, insulating. When asked to choose a material, name the property that fits the job, “borosilicate because it resists thermal shock” scores; “borosilicate because it is better” does not.
Reasoning about materials and their uses
The whole chapter rewards the same skill: reading a use and choosing the material whose properties fit it. Kitchenware that goes from the freezer to the oven needs to survive sudden temperature change, which points to borosilicate glass. A spark plug or a furnace lining needs to resist high temperature and not conduct electricity, which points to a ceramic. A decorative ornament that should sparkle points to lead crystal glass. If you always ask “what property does this use demand?” and then name the glass or ceramic that provides it, you can answer confidently even on an unfamiliar example. It also helps to remember why glass and ceramics are so widely used at all: they are cheap to make from abundant raw materials, chemically inert and durable, which is exactly why they appear everywhere from windows to laboratory apparatus.
Where this fits
This is content standard 8.5 of the Manufactured Substances in Industry chapter, and it completes the chapter’s survey of important manufactured materials. Reinforce it with the chapter revision notes and practise the properties-and-uses and composition questions in the worked examples. In our online 1-to-1 SPM Chemistry lessons, taught in English, from RM50/hr, with a paid one-hour trial, our teachers make sure you can match each type of glass and each ceramic property to the right use, because that matching is what earns the marks in 4541.
Quick recap
- Glass is made from sand (silica, SiO₂) melted with other substances.
- Types: fused silica (high temperature), soda-lime (cheap, everyday), borosilicate (heat/thermal shock), lead crystal (dense, sparkling).
- Ceramics are made from clay hardened by high-temperature heating.
- Ceramics are hard, brittle, inert, heat-resistant and good insulators.
- Always match a property to a use in your answer.
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