SC11 Obtaining and Using Metals

Question 1

What is the reactivity series?

Answer 1

A chart that shows metals in order of their decreasing reactivity

Question 2

What is the reactivity series based on?

Answer 2

The reactivity of metals with water, acids and salts

Question 3

How can you determine the reactivity of a metal?

Answer 3

• place in cold water (most will not react; those that do are the most reactive metals)
• if no reaction, react with steam
• if no reaction, test with acid
• the more reactive the metal, the more vigorous the reaction

Question 4

What is the word equation for when metals react with cold water?

Answer 4

metal + water –> metal hydroxide + hydrogen

Question 5

What is the word equation for metals when they react with steam?

Answer 5

metal + water (g) –> metal oxide + hydrogen

Question 6

What is the word equation for when metal reacts with acid?

Answer 6

metal + acid –> salt solution + hydrogen

Question 7

Name the metals in the reactivity series in its order

Answer 7

Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold

Question 8

Define oxidation

Answer 8

• loss of electrons
• gain of oxygen

Question 9

Define reduction

Answer 9

• gain of electrons
• loss of oxygen

Question 10

Why are displacement reactions redox reactions?

Answer 10

One metal loses electrons whilst the other gains them. Since both are occuring at the same time, we call it a redox reaction

Question 11

What is the reactivity of a metal related to?

Answer 11

Its tendency to form cations during redox reactions. More reactive metals always form the cations during redox reactions

Question 12

Define ore

Answer 12

Rock that contains enough of a compound to extract a metal for profit

Question 13

Define native state of a metal

Answer 13

When the metal is not combined with other elements in a compound: found as the pure, uncombined element

Question 14

What are the two metals that are found in their native state?

Answer 14

Silver and gold

Question 15

Why do metals exist in their native state?

Answer 15

They do not react easily with other elements due to their chemical stability

Question 16

What are the different ways of extracting a metal from its ore?

Answer 16

Electrolysis and Heating with Carbon

Question 17

When can an ore be heated with carbon to extract a metal?

Answer 17

When it is below carbon on the reactivity series

Question 18

Which metals have to go through electrolysis for extraction?

Answer 18

• potassium
• sodium
• calcium
• magnesium
• aluminium

Question 19

Name the metals that can be heated using carbon

Answer 19

• zinc
• iron
• copper

Question 20

What are the two biological methods of metal extraction?

Answer 20

Bioleaching and Phytoextraction

Question 21

Define bioleaching

Answer 21

The use of bacteria to extract metals from their ore

Question 22

Define phytoextraction

Answer 22

Using plants to extract metals from their ore

Question 23

How is the extraction of iron carried out with carbon?

Answer 23

Heated with carbon at high temperatures within a blast furnace

Question 24

Describe what happens in bioleaching

Answer 24

• uses bacteria grown on a low grade re
• which produces a solution containing metal ions called a leachate
• the metal ions can then be extracted through electrolysis or displacement reactions

Question 25

Describe what happens in phytoextraction

Answer 25

- grow plants that absorb metal compounds - then burn them to form ash, from which metal is extracted

Question 26

What are the advantages of bioleaching?

Answer 26

- doesn't require high temperatures - no harmful gases produced - causes less damage to landscape than mining - conserves higher grade ore supplies

Question 27

What are the disadvantages of bioleaching?

Answer 27

- slow - toxic substances such as sulfuric acid can be produced by the process, which is damaging to the environment

Question 28

What are the advantages of phytoextraction?

Answer 28

- can extract metals from contaminated soils - no harmful gases produced - causes less damage to landscape than mining - conserves higher grade ore supplies

Question 29

What are the disadvantages of phytoextraction?

Answer 29

- more £££ than mining some ores - slow - growing plants dependent on weather

Question 30

What are the advantages of recycling metals?

Answer 30

- natural reserves of ore will last longer - helps reduce damage to landscape - reduces pollution: air and noise - less waste metal - economically beneficial

Question 31

What are the disadvantages of recycling metals?

Answer 31

- collecting, sorting and transporting metals is costly - can be more expensive and need more energy to recycle sometimes - management of workers hired in the workforce - products made from recycling the metals may not be the same quality as those made from metals freshly extracted

Question 32

Define **life cycle assessment**

Answer 32

Analysis of the overall environmental impact that a product may have had over its lifetime

Question 33

What are the four stages of an LCA?

Answer 33

1. obtaining and processing raw materials 2. manufacturing and packaging the product 3. using the product 4. disposal + throwing the product