Unit 1: Chapter 3 - Metals And Their Uses

Question 1

Extracting Metals

What factors should we consider when extracting copper ore?

What is Reduction?

How can we displaced oxygen in metal oxides?

How can we extract metal that are more reactive than carbon?

Answer 1

MOST REACTIVE

• Potassium
• Sodium
• Calcium
• Magnesium
• Aluminium

(Carbon)

• Zinc
• Tin
• Lead
• Copper
• Silver
• Gold
• Platinum

HOW TO EXTRACT WITH COKE? (REDUCTION)

A copper ore is only extracted depending on:

• How easy it is to extract
• How metal the ore contains

Depending on the reactivity series, any metal below Carbon in the reativity series can displace the oxygens of metal oxides.

Removal of oxygen in compound is called REDUCTION.

Metals with a higher reativity than carbon would have to be separated with ELECTROLYSIS.

Question 2

Iron and Steels

What is the product of burning iron oxide with carbon?

What is steel and what are the types of steels you can make?
What are the different properties of these steels?
What elements do these steels contain?

Answer 2

To extract Iron(III) oxide, we use a BLAST FURNACE.

Iron(III) Oxide + Carbon -> Iron + CO2

Cast iron (96% iron) is very brittle and hard. It is used for man-hole covers and burning stoves.

ALLOYS (STEEL)

An alloy of iron. Adding elements will change the properties, for e.g.

CARBON STEELS (0.03 - 1.5%) are the cheapest steels and they are used in many products. It is soft and easily shaped.

HIGH CARBON STEELS on the other hand are more hard and brittle. E.g. Cast Iron.

STAINLESS STEELS are used to make utensils and cutlery. They contain much more nickel and chromium which gives resistance to rust and corrosion.

Question 3

Aluminium and Titanium

Properties of aluminium?
Uses of aluminium?
Extraction of Aluminium?

Properties of titanium?
Uses of titanium?
Extraction of titanium?

Answer 3

ALUMINIUM VS. TITANIUM

ALUMINIUM

• Silvery + Shiny
• Low density
• Excellent conductor of energy and electricity
• Maleable
• Ductile

Used to make:

• Cans
• Foil
• Saucepans
• High-voltage electricity cables
• Aeroplanes and space vehicles
• Bicycles

It is separated using electrolysis.

It is first separated from impurities. The oxide is then melted.

It is very expensive as it requires high energy and electricity to extract metal. There is also environmental issues due to the high energy intake.

TITANIUM

• Silvery - White
• Resistant to corrosion
• Denser than aluminum, but less dense than other metals
• Very high melting point (1660C)

Used to make:

• High-performance aircraft
• Racing bikes
• Parts of Jet Engines
• Parts of nuclear reactor
• Replacement Hip Joints

EXTRACTING TITANIUM

Titanium can be extracted by displacing its oxide with carbon. However, it makes it brittle.

We must use a higher reactive metal than titanium to displace titanium. But sodium and magnesium have to both be separated with electrolysis. This is just as expensive as extracting Aluminium.

Before displacement can take place, the titanium ore must be processed. This involves converting the oxide into a chloride, which is then purified. It is then displaced with sodium and magnesium.

Question 4

Extracting Copper

Answer 4

Copper ore - Chalcocite (Cu2S)

1) Smelting (roasting) copper into crude copper is a way to remove it from its ore.

Cu2S + O2 -> Cu + SO2

Scrubbers are used to neutralise acidic gases (SO2 is acidic and can produce acid rain)

Electroysis is also used to purify impure copper extracted by smelting

Approximately 80% of copper is produced through smelting.

2) Alternatively, copper ore can be mixed with sulfuric acid to make copper sulfate solution.

We can then use electrolysis to separate the copper and sulfur. The copper is positive and so it will be attracted the negative electrode. Industry uses many electrolysis cells to make very pure copper.

Copper sulfate can also be displaced by scrap iron as it is more reactive.

Iron + copper sulfate -> iron sulfate + copper

EXTRACTING LOW-GRADE COPPER ORES

There are two ways to extract low-grade copper ores. These are:

• bio-leaching
• phytomining

These methods are useful as they are economical in comparison to traditional methods.

BIOLEACHING

Bacteria feed on low-grade ores. Through chemical and biological processes, we get a solution of copper ions (LEACHATE) from waste copper ore. We can use scrap iron and electrolysis to purify the leachate. 20% of our copper comes from bioleaching.

Bioleaching is a very long process (years) to extract 50% of metal from a low-grade ore.

PHYTOMINING

Plants can absorb copper ions as they grow. The plants are then burned and metals can be extracted from the ash. The copper ions are then ‘leached’ (dissolved) from the ash using sulphuric acid. This produces copper sulfate. This can then be displaced by scrap iron and or electrolysis to make pure copper.

Question 5

Useful Metals

How is brass made?

Why are transition metals useful?

Answer 5

Transition metal properties:

• Good conductors of electricity and heat
• Maleable
• Ductile
• Strong
• Unreactive

COPPER ALLOYS

Brass = Copper + Tin

• Harder
• Workable

-Tough
-Resistant
Used for ship propellers

Used for musical instruments.

ALMUNIUM ALLOYS

Low density and can be combined with a variety of elements. There are many different alloys and properties, however we can use it build planes but even armour plating on tanks.

GOLD ALLOYS

Harder if made as an alloy. E.g. copper and Gold. Pure gold wears away easily. We can also get different colours of gold.

Question 6

Metallic Issues

Answer 6

ENVIRONMENTAL ISSUES: exposed ores and waste slag can make water acidic.

Smelting releases CO2 and SO2 to and can mix to make acid rain. e.g. Carbonic acid.

Destroys habitats of animals and wildlife.

SOCIAL ISSUES: Mining landscape creates eyesores.

Alot of dust and noise produced.

ECONOMIC ISSUES: Smelting can be expensive as it requires large amounts of energy.

Moreover, electrolysis for purifying metal is even more expensive as it also requires energy.

RECYCLING METALS

Recyling aluminium compared extraction of bauxite, there is 95% energy saving.

Less air and land pollution.

Conserves Earth’s reserves of metal ores.

BENEFITS OF METAL CONSTRUCTION:

• Good electrical conductor and not reactive with water
• Lead can be bent easily and is used to seal joints on roofs.
• Steel is strong for girders and scaffolding
• Alluminium alloys are corrosion-resistant.

DISADVANTAGES OF METAL CONSTRUCTION

• Iron and steel severely rust, severely weakening structures. Structures could potentially collapse.
• pollution of the extraction of metal ores.
• Metals are more expensive than other materials such as concrete.