2.5 Extraction & Uses of Metals

Question 1

How are ores formed and what are they?

Answer 1

• When metals chemically combine with other substances.
• A rock that contains enough of the metal to make it worthwhile extracting.

Question 2

What does the Earth’s crust contain?

Answer 2

Metals and metal compounds such as gold, copper, iron oxide and aluminium oxide

Question 3

Why do unreactive metals not have to be extracted chemically?

Answer 3

Unreactive metals do not have to be extracted chemically as they are often found as the uncombined element

Question 4

How does metal reactivity determine metal extraction method?

Answer 4

• Metals higher up the reactivity series are less resistant to oxidation than the metals placed lower down which are more resistant to oxidation.
• Higher placed metals (above carbon) have to be extracted using electrolysis as they are too reactive and cannot be reduced by carbon
• Lower placed metals can be extracted by heating with carbon which reduces them.

Question 5

What method is used to extract most reactive metals? (Potassium - Carbon)

Answer 5

• Electrolysis of the molten chloride or molten oxide.
• Expensive due to electricity requirements.

Question 6

What method is used to less reactive metals? (Zinc - Copper)

Answer 6

• By heating with a reducing agent such as carbon or carbon monoxide
• Cheap process

Question 7

Uses of aluminium and reasons?

Answer 7

• Aircraft bodies (High strength-to-weight ratio (low density)
• Saucepans - (very good conductor of heat and unreactive)
• Overhead electrical cables (Very good conductor of electricity)

Question 8

Uses of copper and reasons?

Answer 8

• Electrical wiring (Very good conductor of electricity and ductile)
• Saucepans (Very good conductor of heat, unreactive, malleable)
• Water pipes (Unreactive so does not react with water)

Question 9

What are alloys?

Answer 9

• Alloys are mixtures of metals, where the metals are mixed together physically but are not chemically combined.
• They can also be made from metals mixed with nonmetals such as carbon

Question 10

Why are alloys much harder than the pure metal?

Answer 10

• Alloys contain atoms of different sizes, which distorts the regular arrangements of atoms.
• This makes it more difficult for the layers to slide over each other, so they are usually much harder than the pure metal

Question 11

What is haematite and bauxite?

Answer 11

• Haematite is an iron oxide ore.
• Bauxite is an aluminium oxide ore.

Question 12

What are 4 types of steel?

Answer 12

• Mild steel
• High carbon steel
• Low alloys steel
• Stainless steel

Question 13

Advantages of using alloys over pure metals?

Answer 13

• Greater strength
• Greater hardness
• Increased resistance to corrosion
• Increased resistance to extreme temperatures