C1.3 Metals and their uses

Metals are very useful in our everyday lives. Ores are naturally occurring rocks that provide an economic starting point for the manufacture of metals. Iron ore is used to make iron and steel. Copper can be easily extracted but copper-rich ores are becoming scarce so new methods of extracting copper are being developed. Aluminium and titanium are useful metals but are expensive to produce. Metals can be mixed together to make alloys.

Students should be able to:

■ consider and evaluate the social, economic and environmental impacts of exploiting metal ores, of using metals and of recycling metals

■ evaluate the benefits, drawbacks and risks of using metals as structural materials.

Key wordsOresBauxiteHaematiteMetalEconomicalExtractPurifiedReductionReactivityElectrolysis

PhytominingBioleachingDisplacementBlast furnaceAlloyMixturesCompoundsSteelTransition metalsDensityCorrosion

a) Ores contain enough metal to make it economical to extract the metal. The economics of extraction may change over time.

Two common ores are bauxite (aluminium ore, Al2O3) and haematite (iron ore Fe2O3)

Bauxite Three different types of haematite

b) Ores are mined and may be concentrated before the metal is extracted and purified.

c) Unreactive metals such as gold are found in the Earth as the metal itself but most metals are found as compounds that require chemical reactions to extract the metal.

Question: Are some metals more reactive than others?

Hypothesis: Some metals are more reactive than others

Zn CuMg Pb

Hydrochloric acid

VARIABLES

Independent

What we changed

Dependent

What’s changed as a result

Controlled

What’s kept the same

VARIABLES

Independent

What we changed

The type of metal

Dependent

What’s changed as a result

The rate of reaction: How long it takes to dissolve How many bubbles per minute or second

Controlled

What’s kept the same

The shape and size of the metalThe acid – strength, type and amountThe time

The Reactivity Series

PotassiumSodiumLithiumCalciumMagnesiumAluminium

ZincIronTinLead

CopperSilverGoldPlatinum

Most reactive

Least reactive

As well as the above metals you may also find two non metals in the series.

Carbon

Hydrogen

Since most metal ores contain the metal oxide, then it is obvious

that oxygen must be removed from the ore in order to produce

the metal itself.

The removal of oxygen from a compound is called reduction.

This is opposite from the addition of oxygen to a substance

which is called oxidation.

Metal oxide – oxygen metal

REDUCTION

Metal + oxygen metal oxide

OXIDATION

The removal of oxygen from the metal ore can be done in a number of ways – it depends upon the metal’s position in the reactivity series.

3. For each of these – state if the metal will reduce the oxide

a. Aluminium v magnesium oxide

b. Magnesium oxide v iron

c. Iron oxide v aluminium

d. Carbon v aluminium oxide

e. Iron oxide v carbon

4. Metal X will reduce aluminium oxide but not calcium oxide.Use the resistivity series to identify X.

5. Metal Y will reduce copper oxide but not iron oxide – which possible metals could it be?

Since carbon is more

reactive than iron,

then it can be used to

reduce iron oxide to

iron. This is done in

the Blast Furnace.

Carbon is less reactive than aluminium so cannot

be used to reduce aluminium oxide to aluminium.

Another process called electrolysis must be used.

Properties of metals

CHeSS DMS

Conductor

Shiny

Sonorous

High mpt

Malleable

Ductile

SolidMETALS

Conductor

Shiny

Sonorous

High mpt

Malleable

Ductile

SolidMETALS

Shiny Solid

Malleable

Sonorous

Ductile

CHeSS DMS