Transition Metals, Alloys and Corrosion - Paper 1

Question 1

List the typical properties of transition metals.

Answer 1

• High melting point.
• High density.
• Formation of coloured compounds.
• Catalytic activity of the metals and their compounds.

Question 2

What causes corrosion?

Answer 2

The oxidation of metals.

Question 3

How can rusting of iron be prevented?

Answer 3

• Exclusion of oxygen
• Exclusion of water
• Sacrificial protection

Question 4

Explain the process of electroplating.

Answer 4

Electroplating involves using electrolysis to put a thin layer of a metal on the object.

Question 5

Explain the potential advantages of electroplating.

Answer 5

Electroplating can improve the appearance of an object without the whole object being made from the coating material.
It can also improve the object’s resistance to corrosion by sacrificial protection.

Question 6

Explain why alloys are often stronger than pure elements.

Answer 6

Atoms of different elements are different sizes, distorting the regular lattice structure of the alloy, so layers of atoms cannot slide over each other so easily.

Question 7

Explain why iron is alloyed with other metals.

Answer 7

• Iron alloys have different properties:
• Mild steel - carbon - malleable, ductile
• Tool steel - tungsten - hard, resistant to high temperatures
• Stainless steel - chromium - hard, resistant to rusting

Question 8

Explain the properties and uses of aluminium.

Answer 8

Aluminium does not react with water. Its surface is protected by a natural layer of aluminium oxide, allowing it to resist corrosion. Aluminium foil is used in the home for wrapping and storing food because it does not react to substances in food. It is malleable, so it is easily folded into shape around the food.

Question 9

Explain the properties and uses of an alloy of aluminium.

Answer 9

Aluminium has a low density, so pieces of aluminium are relatively lightweight.
Magnalium is stronger than aluminium alone but still has a low density. It is used to make aircraft parts.

Question 10

Explain the properties and uses of copper and brass.

Answer 10

Copper and brass resist corrosion and are good electrical conductors. Copper is a better conductor than brass, and it is used in electrical wiring. Brass is stronger than copper, so it is used for the pins in electrical plugs.

Question 11

Explain the properties and uses of gold.

Answer 11

Gold is a very soft and malleable metal. It is also very unreactive, so it resists corrosion and stays shiny. The gold used for jewellery is gold alloyed with other metals, often copper. This makes the jewellery much stronger while keeping its ability to stay shiny.