Polymers are light and flexible, glass is transparent and brittle, and ceramics are hard, brittle and heat resistant. A good answer names the property first and then the job it suits.
This lesson follows explaining alloy properties and belongs to industrial chemistry. Confirm the exact materials in your textbook, because the set covered can differ by book.
What does each material offer?
Polymers are made of long molecules. They are light, can be moulded into almost any shape, and do not conduct electricity. Most soften when heated, which limits where they can be used.
Glass is made by melting sand with other substances and cooling the liquid. It is transparent, hard and does not react with most chemicals, but it shatters when hit.
Ceramics are made by shaping clay and heating it in a kiln. They are very hard, resist high temperatures and do not conduct electricity, but they also break instead of bending.
Worked example: one table, three matches
An original question gives this table and asks which material suits each object.
| Property | Polymer | Glass | Ceramic |
|---|---|---|---|
| Mass of a 100 cm³ piece | Low | Medium | Medium |
| Transparent | Sometimes | Yes | No |
| Survives a kiln-level temperature | No | No | Yes |
| Bends without breaking | Yes | No | No |
Objects: a jar for a chemistry demonstration where students must see the liquid, a flexible tube for carrying water, and a lining inside a furnace.
The jar needs to be seen through, and to be unreactive. Glass gives both. Some polymers are clear, but the table marks only glass as transparent every time.
The tube needs to bend. Only the polymer bends without breaking.
The furnace lining needs to survive very high temperatures. Only the ceramic does in this table.
Each choice names the property first, then the object, and uses the table. That is what a marker looks for.
The mistake that costs marks
The common error is to treat brittle as another word for weak. Students write, “Glass is weak, so it breaks.” That is wrong, because a glass plate can carry a load and still shatter if struck.
| Wrong | Right |
|---|---|
| “Ceramic is weak because it breaks” | “Ceramic is hard but brittle, so it breaks instead of bending” |
| “Plastic is used because it is cheap” | “Plastic is used because it is light, flexible and can be moulded” |
| “Glass is used because it is hard” | “Glass is used because it is transparent and unreactive” |
The repair is to give the exact property that matches the job. Cost can be added as an extra point, but it rarely earns the main mark.
Check yourself
A school wants a container for storing a strong acid in the laboratory. Choose between a polymer bottle and a glass bottle using two properties, and state one limitation of your choice.
Answer
Choose glass, because it does not react with most chemicals and does not soften at normal laboratory temperatures. A polymer may be damaged by some chemicals and can soften when warm.
Limitation: glass is brittle, so it must be handled carefully and stored where it will not fall. Some polymers also resist acids, so in a real question use the information supplied.
What to study next
The next lesson, relating manufacturing choices to material properties, adds cost, shaping and recycling to the choice. Track wording slips in the mistake log and paper-error review.
For help turning these comparisons into full-mark sentences, see online one-to-one Science tuition.