Section 4 - Extracting metals and equilibria - Reactivity, displacement, extraction, recycling and life cycle assessments

Question 1

What can oxidation and reduction mean in terms of oxygen?

Answer 1

Oxidation - reaction with or addition of oxygen

Reduction - removal of oxygen

Question 2

What do combustion reactions involve and what type of reaction?

Answer 2

Involve oxidation and are exothermic

Question 3

What does carbon in the reactivity series of metals show?

Answer 3

Shows how the metal can be extracted from its ore

Question 4

What does hydrogen in the reactivity series of metals show?

Answer 4

Shows reactivity of metals with dilute acids

Question 5

How resistant to oxidation are most reactive elements?

Answer 5

Most reactive are least resistant to oxidation. More likely to form cations and oxidise

Question 6

Equation metal and water? Less reactive metal and steam?

Answer 6

Metal + water –> metal hydroxide + hydrogen

Less reactive metal + steam –> metal oxide + hydogen

Question 7

How are displacement reactions redox reactions?

Answer 7

Reduction and oxidation occur simultaneously

Question 8

How are metals that are above carbon in the reactivity series extracted?

Answer 8

Using electrolysis of molten compounds

Question 9

How are metals below carbon in the reactivity series extracted?

Answer 9

By reduction using carbon

Question 10

What can elements like gold and silver found as and why?

Answer 10

Found as uncombined elements as they are unreactive with other elements

Question 11

Con for using electrolysis for extracting metals?

Answer 11

Very expensive for electricity during electrolysis and melting metal ore

Question 12

2 examples of biological methods to extract metals? What do they both use

Answer 12

Bioleaching and phytoextraction. Both use living organisms

Question 13

What is bioleaching?

Answer 13

Using bacteria to separate metals from their ores. Bacteria get energy from bonds between atoms in ore. Leachate (solution produced by process) contains metal ions, which can be extracted

Question 14

What is phytoextraction?

Answer 14

Involves growing plants in soil that contains metal compounds. Metal gradually builds up in leaves and then plant is harvested, dried and burned in furnace. Ash contains metal compounds from which metal can be extracted

Question 15

What does a life cycle assessment show?

Answer 15

Total environmental costs

Question 16

4 stages of a life cycle assessment?

Answer 16

Choice of material - Extracting, obtaining and refining metal
Manufacture
Product use
Disposal - Landfill or incenerated