Question 52
In groups, study Figure 7.26 and Table 7.2 and discuss the questions.
Figure 7.26 — Different alloys and their uses:
- **Brass:** an alloy of copper and zinc. Softer than bronze and easier to shape; very shiny. Used for curved objects such as doorknobs, plumbing fixtures and musical instruments.
- **Stainless steel:** a type of steel containing iron and chromium, as well as nickel and carbon. Shiny, strong and resistant to rusting. Used for sinks, utensils and other objects exposed to water.
- **Bronze:** an alloy of copper and tin. Both metals are relatively soft, but form a much stronger alloy when mixed. Used for statues, coins and small parts in cars and machines.
- **Sterling silver:** an alloy of silver and copper. Pure silver is very soft; adding copper gives a stronger, harder alloy. Used for jewellery and silverware (cutlery, platters, teapots and coffee pots).
Table 7.2 — Comparing some properties of iron, carbon and steel
| Property | Iron (metal) | Carbon (non-metal) | Steel (mixture) |
|---|---|---|---|
| Appearance | shiny | dull | shiny |
| Strength | relatively weak | depends on form | strong |
| Ductility | ductile | non-ductile | ductile |
| Malleability | malleable | non-malleable | malleable |
| Hardness | relatively soft | depends on form | hard |
| Density | high | low | high |
| Electrical conductivity | good | depends on form | good |
| Thermal conductivity | good | depends on form | good |
| Reactivity | high | low | low |
| Flammability | low | high | low |
Which of the properties in the table are physical properties?
Figure 7.26 — Different alloys and their uses:
- **Brass:** an alloy of copper and zinc. Softer than bronze and easier to shape; very shiny. Used for curved objects such as doorknobs, plumbing fixtures and musical instruments.
- **Stainless steel:** a type of steel containing iron and chromium, as well as nickel and carbon. Shiny, strong and resistant to rusting. Used for sinks, utensils and other objects exposed to water.
- **Bronze:** an alloy of copper and tin. Both metals are relatively soft, but form a much stronger alloy when mixed. Used for statues, coins and small parts in cars and machines.
- **Sterling silver:** an alloy of silver and copper. Pure silver is very soft; adding copper gives a stronger, harder alloy. Used for jewellery and silverware (cutlery, platters, teapots and coffee pots).
Table 7.2 — Comparing some properties of iron, carbon and steel
| Property | Iron (metal) | Carbon (non-metal) | Steel (mixture) |
|---|---|---|---|
| Appearance | shiny | dull | shiny |
| Strength | relatively weak | depends on form | strong |
| Ductility | ductile | non-ductile | ductile |
| Malleability | malleable | non-malleable | malleable |
| Hardness | relatively soft | depends on form | hard |
| Density | high | low | high |
| Electrical conductivity | good | depends on form | good |
| Thermal conductivity | good | depends on form | good |
| Reactivity | high | low | low |
| Flammability | low | high | low |
Which of the properties in the table are physical properties?
