Topic 4a

Question 1

4.1
Explain how to deduce the relative reactivity of some metals

Answer 1

React metal w/ acid
-More reactive metals react explosively + produce lot of H₂
-As go down reactivity series reactions gradually less violent

React metal w/ water
-Only most reactive metals react

Measure temp
-More reactive = more heat

(Needs to be fair test:
-same SA
-same mass
-same type+conc+v of acid each time)

Question 2

4.1
Explain why reactive metals will produce a lot of hydrogen when reacted with an acid

Answer 2

Metal + Acid -> Salt + H₂

Question 3

4.1
Describe how K, Mg, Zn, Fe and Cu would react with an acid

Answer 3

K: Explosively + lot of H₂
Mg: Bubbles, solid metal dissolve
Zn & Fe: Fewer bubbles
Cu: Does not react

Question 4

4.1
State whether K, Zn, Fe and Cu would react with water

Answer 4

K: Yes
Zn, Fe & Cu: No

Question 5

4.2
Define the term redox reaction

Answer 5

Both oxidation & reduction occur

Question 6

4.2
What is a displacement reaction an example of?

Answer 6

Redox reaction

Question 7

4.2
Explain why the reaction between zinc & copper sulfate is a redox reaction [3 marks]

Answer 7

-In displacement reaction 1 substance oxidised (loses electrons) & another is reduced (gains)
-Zn atoms lose 2 electrons -> Zn^2+ ions
-Cu^2+ ions gain 2 electrons -> Cu atoms

Question 8

4.2
What is a displacement reaction?

Answer 8

More reactive element takes place of less reactive 1

Question 9

4.3
Use a mnemonic to learn the reactivity series (include carbon and hydrogen)

Answer 9

Please -> Potassium
Sady -> Sodium
Come -> Calcium
My -> Magnesium
Aunt -> Aluminium
(CARBON)
Zehra -> Zinc
Is -> Iron
(HYDROGEN)
Crying -> Copper
So -> Silver
Good -> Gold

Question 10

4.4
Define the term ore

Answer 10

Rock which metal can be extracted from

Question 11

4.4
Where are unreactive metals found?

Answer 11

Earth’s crust as uncombined elements

Question 12

4.5
Define the term oxidation and reduction (referring to oxygen)

Answer 12

Oxidation - Gain of oxygen
Reduction - Loss of oxygen

Question 13

4.6
What does the extraction of metals involve?

Answer 13

Reduction of ores

Question 14

4.7
State how would you extract different metals

Answer 14

-Anything above carbon -> electrolysis
-Zn, Fe, Cu -> Heat w/ carbon
-Ag, Au -> Found as uncombined elements

Question 15

4.7
Explain why metals above carbon in the reactivity series cannot be extracted using heating with carbon

Answer 15

More stable than C so C will not displace them

Question 16

4.7
Explain why zinc, iron and copper can be extracted by heating with carbon

Answer 16

C = more reactive so will displace them

Question 17

4.7
Which is preferred for the extraction of metals: heating with carbon or electrolysis? Why?

Answer 17

Heating w/ C because electrolysis = expensive

Question 18

4.8
What is a low grade ore?

Answer 18

Contains very small amount of metal -> hard to economically extract (make it cost-effective)

Question 19

4.8
Describe the process of phytoextraction/phytomining (same thing)

Answer 19

-Grow plants on land containing desired metal compound
-Plants absorb metal compounds & concentrate it in tissue
-Plants harvested + burned
-Ash contains relatively high conc of metal compound

Question 20

4.8
Describe the process of bioleaching

Answer 20

-Grow bacteria on low grade ore
-Bacteria carry out chemical reactions
-Produce solution called leachate
-Leachate = contains metal compound needed

Question 21

4.9
Define the term corrosion

Answer 21

Metal oxidised (reacts w/ O₂) -> becomes weaker over time

Question 22

4.9
Define the term rusting

Answer 22

-Corrosion of iron
-Requires water & oxygen

Question 23

4.9
What will cause an object to corrode more?

Answer 23

Higher reactivity

Question 24

4.11
Describe the lifecycle/life time assessment of a product

Answer 24

CHOICE OF MATERIAL
-Which material?
-How much energy to extract material?
-Pollution?
MANUFACTURE
-How much energy to manufacture?
-Toxic gases?
-Waste products used/disposed of easily?
PRODUCT USE
-Product harmful to environment?
HOW WILL IT BE DISPOSED OF?
-Burning -> toxic/greenhouse gases + run out of resources
-Landfill -> visual pollution + run out of resources

Question 25

4.12
Describe how you would evaluate data from a lifecyle assessment of a product

Answer 25

Compare all stages & suggest best material

Question 26

Why can aluminium be used in drink cans?

Answer 26

-Oxidises quickly -> forms protective layer (aluminium oxide)
-Stops further corrosion

Question 27

Outline the 4 advantages of recycling metals

Answer 27

-Reduce need to mine (conserve natural resources)
-Saves energy
-Less GHG
-Less waste in landfills

Question 28

State an 3 advantages of extracting a metal by phytoextraction rather than from its ore

Answer 28

-Less noise due to mining
-Less CO2
-Conserves ores