Obtaining and using metals

Question 1

What are the products when a metal reacts with cold

water?

Answer 1

Metal hydroxide and hydrogen gas

Question 2

What are the products when a metal reacts with

steam?

Answer 2

Metal oxide and hydrogen gas

Question 3

Write the chemical equation for the reaction that

occurs when calcium reacts with cold water

Answer 3

Ca + 2H2O → Ca(OH)2
+ H2

(Check google if unsure)

Question 4

Write the chemical equation for the reaction that

occurs when zinc reacts with steam

Answer 4

Zn + H2O → ZnO +H2

Question 5

What are the products when a metal reacts with

dilute acids?

Answer 5

Salt and hydrogen

Question 6

If a metal reacts with cold water, what does it

suggest about the reactivity of this metals?

Answer 6

It suggests the metal is very reactive as
only the most reactive metals can react
with cold water

Question 7

A metal reacts with oxygen but not acid or cold
water. What does this suggest about the reactivity of
this metal?

Answer 7

Not very reactive, most metals react with

oxygen

Question 8

Name a metal which will not react with water, acid or

oxygen

Answer 8

Gold

Question 9

Describe an experiment that uses displacement to compare the reactivity of two metals

Answer 9

Add a solid metal to a salt solution (the salt must contain a
different metal).

If the solid metal is more reactive, it will gradually disappear,
displacing the metal that was in the salt solution.

If nothing happens, the metal in the salt is more reactive and
can’t be displaced.

Question 10

What would you expect to observe when magnesium

is added to copper sulfate solution?

Answer 10

The copper sulfate solution is blue.

Magnesium is more reactive than copper so
when magnesium is added the blue solution
decolourises and copper coats the surface of
the magnesium

Question 11

Why can a displacement reaction be called a redox

reaction? Explain in terms of electron transfer

Answer 11

A redox reaction occurs when reduction and oxidation are
taking place in the same reaction.

In a displacement reaction, the more reactive metal atoms
lose electrons to form ions (oxidation) and the less reactive
metal ions gain electrons to form the element (reduction)

Question 12

‘Fill in the gap: ‘The reactivity of a metal is related to

its tendency to form _______ ’

Answer 12

Cations (positive ions)

Question 13

Which metals are most easily oxidised?

Answer 13

The metals highest in the reactivity
series. More reactive metals are more
likely to react with water and dilute acids
to form cations.

Question 14

Where are most metals extracted from?

Answer 14

From ores found in the Earth’s crust

Question 15

What is an ore?

Answer 15

A rock which contains metals often
chemically combined with other
substances

Question 16

Which metals are found in the earth’s crust as

uncombined elements?

Answer 16

Unreactive metals

Question 17

Explain what oxidation means in terms of oxygen

Answer 17

Gain of oxygen

Question 18

Explain what reduction means in terms of oxygen

Answer 18

Loss of oxygen

Question 19

Most ores contain metals chemically combined with
oxygen. What process must be carried out to extract
the metal?

Answer 19

Reduction

Question 20

How can metals be extracted from their ores?

Answer 20

Reduction with carbon: Can only be done if
the metal is less reactive than carbon (links to
reactivity series).

Electrolysis: Can be done with all metals, but
requires a large amount of energy (high cost).

Question 21

How would you extract iron from its ore?

Answer 21

Iron is less reactive than carbon so can be
extracted by reduction with carbon.

Electrolysis could also be used, but this would
use a lot of unnecessary energy (high cost).

Question 22

What is the chemical equation for the reduction of

iron with carbon?

Answer 22

2Fe2O3 + 3C → 4Fe + 3CO2

Check google if unsure

Question 23

How can aluminium be extracted from its ore?

Answer 23

Aluminium is more reactive than carbon so
electrolysis must be used.

When the molten ore undergoes electrolysis,
the metal forms at the cathode.

Question 24

When aluminium is extracted from aluminium oxide, why is it first dissolved in molten cryolite?

Answer 24

Aluminium oxide has a very high melting point. It is dissolved in molten cryolite to produce an electrolyte with a lower melting point, reducing energy usage and cost.

Question 25

How can plants be used as an alternative metal extraction method? How does it work?

Answer 25

Phytoextraction:

Plants are grown in areas with metals in the soil. The
plants take up metals through their roots and concentrate
them in their shoots and leaves. These plants are burned
and the metals are removed from the ash.

Question 26

How can bacteria be used as an alternative metal extraction method? How does it work?

Answer 26

Bacterial extraction:

Some bacteria absorb metal compounds. These
bacteria produce solutions called leachates containing
the metals. Scrap iron can be used to remove the
metal from the leachate.

Question 27

What are the limitations of biological methods of

extraction?

Answer 27

• Only suitable for low grade ores with smaller
  quantities of metals.
• Slow processes.
• Require displacement or electrolysis for the
  final step.

Question 28

How is a metal’s relative resistance to oxidation

related to its position in the reactivity series?

Answer 28

Oxidation is the loss of electrons. Metals
lower in the reactivity series are less
reactive. This means they are less likely to
form their cations so are more resistant to
oxidation.

Question 29

What are the advantages of recycling metals?

Answer 29

• Economically beneficial because electrolysis is expensive.
• Prevents the detrimental environmental impact of mining and
  extraction of new metals.
• Less waste produced so less landfill.
• Less energy required compared to electrolysis.
• More sustainable - not using up the finite resources.
• Recycling process provides employment.

Question 30

What is a life cycle assessment?

Answer 30

Analysis of the overall environmental
impact that a product may have
throughout its lifetime.

Question 31

What different factors does a life cycle assessment

of a product consider?

Answer 31

• Extraction and processing of raw materials.
• Manufacturing.
• Packaging and transportation.
• Use of the product.
• Disposal.