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CHEMISTRY > C6 - Global challenges > Flashcards

C6 - Global challenges Flashcards

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1
Q

What are ores?

A

Naturally occurring rocks which contain metal compounds

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2
Q

What is the name of the aluminum ore and what is it made of?

A

Bauxite (aluminum oxide)

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3
Q

What is the name of the iron ore and what is it made of?

A

Haematite (Iron oxide)

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4
Q

What is the name of the copper ore and what is it made of?

A

Malachite (Copper Carbonate)

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5
Q

What does Extraction mean?

A

Obtaining pure metal from ore

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6
Q

Reactivity series for metal extraction?

A

Please Send Lions Cats Monkeys And Cute Zebras Into Lovely Countries Signed General Penguin

Potassium                  
Sodium                  
Lithium        
Calcium                 
Magnesium
Aluminum
Carbon
Zinc
Iron
Lead
Copper
Silver
Gold
Platinum
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7
Q

What is group 1 of reactivity series and how are the metals extracted?

A 
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminum

Extracted by electrolysis (using electricity)

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8
Q

What is group 2 of reactivity series and how are the metals extracted?

A

Zinc
Iron
Lead
Copper

Extracted by reduction using Carbon

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9
Q

What is group 3 of reactivity series and how are the metals extracted?

A

Silver
Gold
Platinum

No extracted needed as they are found as pure metals

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10
Q

Why can’t the reduction using carbon method work on the group 1 of the reactivity series?

A

They are more reactive than carbon, therefore carbon cannot remove the oxygen.

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11
Q

Why do most metals exist as compounds in Earth’s crust and some exist as native metals?

A

Most metals exist as compounds as they are too reactive to exist on their own.

Some metals (like silver, gold, platinum ) are native metals (pure metals) as they are too unreactive to form compounds.

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12
Q

Example of reduction using carbon with iron oxide?

A

Iron oxide + carbon -> Iron + Carbon dioxide

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13
Q

Why is aluminum oxide melted when extracting aluminium?

A

When solid it cannot conduct electricity (in electrolysis) as ions are not mobile and in liquid the ions are mobile and can conduct electricity

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14
Q

Why is Cryolite used in extraction of aluminum oxide?

A

It lowers the melting point of aluminum oxide - which has a very high melting point

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15
Q

Equipment for extraction of aluminum from aluminum oxide?

A
  • Graphite (Carbon) anodes in a solution of molten bauxite and Cryolite
  • Solution in a steel container with the inside of the container being the cathode
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16
Q

Word and symbol equation of the extraction of aluminum from bauxite.

A

Aluminum oxide -> Aluminum + Oxygen gas

2Al2O3 -> 4Al + 3O2

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17
Q

What attracts and happens at the cathode in the extraction of aluminum from bauxite?

A

Aluminum ions (+) attract to the cathode (-) and reduction occurs to from aluminum atoms:

Al(3+) + 3e- -> Al

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18
Q

What attracts and happens at the anode in the extraction of aluminum from bauxite?

A

Oxygen ions (-) attract to the anode (+) and oxidation occurs to from Oxygen atoms:

2O(2-) - 4e- -> O2

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19
Q

Why does the anode become smaller as the extraction of aluminum takes place?

A

The oxygen gas produced at the anode reacts with the Carbon anodes to produce Carbon dioxide.

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20
Q

Some uses of alumnium?

A

Bicycles: as aluminum is light and doesn’t rust
Aeroplanes: Low density (light)

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21
Q

What is phytomining definition?

A

Extracting copper from low grade ores by hyperaccumulator plants.

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22
Q

What is bioleaching definition?

A

Extracting copper from low grade ores by microorganisms like bacteria

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23
Q

What is a hyperaccumulator plant?

A

A plant that can absorb toxic metals without dying used in phytomining

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24
Q

How do we extract copper via phytomining?

A

1) Grow hyperaccumulator plants over low grade copper ore
2) Roots of plant absorb copper ions from soil via active transport
3) Once copper ions are in leaves, harvest and burn the plant to produce ash
4) The ash is rich in copper compounds - copper has reacted with oxygen in combustion to form copper oxide.
5) Use displacement method or electrolysis to extract pure copper

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25
How do we extract copper via bioleaching?
1) Bacteria feeds on the low grade copper ore 2) A solution is produced (called a leachate) containing copper compound (Like copper sulphate) 3) Iron can be used to displace copper from the copper compound IRON + COPPER SULPHATE -> IRON SULPHATE + COPPER
26
Advantages and disadvantages of: - Phytomining - Bioleaching
PHYTOMINING Adv: Conserves supply of more valuable copper ores from being used up Dis: Slow BIOLEACHING: Adv: Doesn't require high temperature like traditional mining Dis: Can produce toxic substances like sulphuric acid Slow
27
What is the Haber process? | - Word and symbol equation
Creating Ammonia from Nitrogen and Hydrogen Hydrogen + Nitrogen ⇌ Ammonia 3H2 + N2 ⇌ 2NH3
28
Where do we get the reactants for the Haber process? | And disadvantage of it
NITROGEN: The air from cryogenic distillation - distillation by cooling the air instead of heating or extracted from air DISADVANTAGE: - Requires lots of energy - Needs to be done multiple times to make sure no oxygen contaminates the Nitrogen gas as it can damage the Iron Catalyst HYDROGEN: From petroleum after distillation of crude oil by reacting methane with steam. Sulfur has to be removed as an impurity damages the catalyst or taken from naturally occurring gas DISADVANTAGE: -More energy required so more cost
29
What are some uses for ammonia?
- Fertilisers - Nitric acid - cleaning fluids
30
Conditions for Haber Process?
- High pressure of 200 atm increases ammonia yield as it shifts equilibrium to the right - High temperature decreases percentage yield but increases rate of reaction - A compromise 450 degrees Celsius - optimum temp to give a fast reaction and high percentage yield - Catalyst of Iron increasing rate of reaction but not percentage yield
31
``` Haber process: What does High temperature do? What does low temperature do? What does High pressure do? What does Low pressure do? What does adding a catalyst do? ```
N2 + 3H2 -> 2NH3 (Forward = Exothermic) High temp: Lower yield of ammonia Low temp: High yield of ammonia High pressure: High yield, equilibrium shifted to the right Low pressure: Low yield, equilibrium shifted to the left Catalyst: Nothing to the yield, Increased rate of reaction
32
Factors that increase or decrease the cost of the Haber process?
Increased cost: - High temperature - High pressure - Machinery / Automation Lower cost: - Catalyst - Recycling material
33
What is the contact process?
Producing Sulphuric acid or oleum from the raw materials water, Sulphur and oxygen
34
Step to contact process (including word and symbol equations):
1) Sulphur burnt in Oxygen to produce Sulphur dioxide Sulphur + Oxygen -> Sulphur dioxide S(l) + O2(g) → SO2(g) 2) Sulphur dioxide reacted with Oxygen to produce Sulphur trioxide Sulphur dioxide + Oxygen ⇌ Sulphur trioxide 2SO2(g) + O2(g) ⇌ 2SO3(g) 3) Sulphur trioxide dissolved in water to produce Oleum Sulphur trioxide + water -> Oleum 2SO3 + H2O → H2S2O7 4) Sulphur trioxide reacts with water to form sulphuric acid Sulphur trioxide + water -> Sulphuric acid SO3 + H2O → H2SO4
35
Conditions for Contact process:
- 1 or 2 atmospheric pressure - Around 450 degrees - Catalyst Vanadium Oxide (V2O5)
36
``` Contact process: What does High temperature do? What does low temperature do? What does High pressure do? What does Low pressure do? What does adding a catalyst do? ```
High temperature: Lower yield as equilibrium shifts left and increases rate of reaction Low temperature: Higher yield as equilibrium shifts right and slower rate of reaction High pressure: Decreases yield but faster rate of reaction Low pressure: Increases yield, and decreases rate Vanadium oxide catalyst: Nothing occurs to yield but rate of reaction increases
37
Plants and solid fertilisers:
Plant roots cannot absorb solid fertilizers but they can absorb dissolved fertilizers (in liquid form)
38
What are the 3 essential elements in fertilisers?
Nitrogen (N) Phosphorous (P) Potassium (K)
39
What does minerals do in plants?
Nitrates: used to make amino acids for proteins needed for cell growth Phosphates: Used to make DNA and cell membranes for respiration and growth Potassium: helps enzymes for respiration and photosynthesis Magnesium: makes chlorophyll for photosynthesis
40
Plant minerals and plant deficiencies?
Lack of nitrates -Poor growth / yellow leaves Lack of Phosphates -Poor root growth and purple leaves Lack of Potassium: Poor flower + fruit growth and spotted leaves Lack of magnesium: yellow leaves
41
How are fertilizers chemically formed?
Formed by a base + acid by titration EG Ammonium sulphate - made from ammonia hydroxide (alkali) and sulphuric acid Ammonium nitrate - made from ammonia hydroxide and nitric acid
42
Method for creating a fertilizers?
1) Fill burette with acid and measure starting volume 2) Use pipette to measure specific amount of ammonium (ammonia hydroxide) and transfer it to a flask 3) Add pH indicator 4) Slowly begin adding acid until there is colour change - the alkali has been neutralized - and measure the amount of acid needed to neutalise alkali 5) Repeat steps until there is a consistent result 6) Fertiliser is contaminated with pH indicator causing it to be coloured so titration needs to be done again without indictor adding volume of acid required to neutalise alkali gathered from previous 7) Neutralised solution needs to be evaporate is rid of water from it because water is also a product (EG: ammonia hydroxide + sulphuric acid -> ammonia sulphate + water) 8) Evaporate solution, to form crystal and filter off crystals to leave Fertiliser
43
What is the LCA (Life cycle assessment)?
- a way of analyzing the 'life' of a product and see how much water and energy is used and the effects in the environment
44
General steps to the LCA?
1) Raw materials (eg biodegradable, where it came from, transportation) 2) Manufacture (toxic chemicals produced, energy/water required etc.) 3) Transportation 4) Uses (reusable, last long) 5) Disposing (recyclable, landfill vs incinerators)
45
Definitions for LCA topic: ``` Biodegradable Objectivity Subjectivity Quantitative Qualitative ```
Biodegradable: Can be decomposed by bacteria Objectivity: fact Subjectivity: opinion Quantitative: numbers Qualitative: descriptive (words)
46
4 materials that can be recycled?`
- Paper - Plastic - Glass - Metals
47
Reduce, Reuse, Recycle definitions and one advantage?
Reduce - stop using as much materials in the first place (like walking instead of driving) ADV - Reduces environmental impacts and waste Reuse - Reusing items instead of disposing or recycling them ADV - Reduces rubbish in landfills and incinerators Recycling - Crushing, melting materials into a new product ADV - Reduces need for quarreling natural resources
48
What is an alloy?
A mixture of two or more metals to change the metals properties
49
Why are alloys more stronger than pure metals?
Pure metals consist of ions in a lattice therefore when hit the layers can slide over each other making them soft. However, in alloys the different sized particles disrupt the lattice arrangement making it harder for layers to slide over each other - they are stronger
50
What is the alloy bronze made of and its uses?
Copper and tin -Used for statues
51
What is the alloy brass made of and its uses?
Copper and zinc -used for musical instruments and water taps
52
What is the alloy Steel made of?
Carbon and Iron | The higher the carbon percentage the stronger the alloy but it is more brittle (break easier)
53
What is the alloy stainless steel made of and its uses?
Nickel and Chromium - Doesn't rust
54
What is the alloy Solder made of?
Lead and tin
55
What is the alloy Amalgam made of?
Any alloy containing mercury
56
Why is gold alloys used in jewellery instead of the metal itself?
The metal gold is too soft therefore alloys containing gold are used measured in carats.
57
What equation do you use to find the percentage of a metal present in its alloy?
Percentage of metal in alloy = (Mass of metal / Total alloy mass) x 100
58
What is the difference between Rusting and Corrosion?
Rusting - occurs only with Iron | Corrosion - occurs with any other metal
59
Conditions for Rusting?
- Oxygen - Water - Salt (Not required but catalysis rusting process)
60
Word and symbol equation for rusting?
Iron + water + oxygen -> Hydrated Iron (III) oxide | 4Fe + 3O2 + 2H2O -> 2Fe2O3.H20
61
How to prevent rusting?
- Removing the reactants from the rusting equation: water or oxygen - Cover with physical material - like oiling or painting so iron isn't exposed to air - Sacrificial protection - Galvanising
62
Sacrificial protection vs Galvanising vs tinning:
Sacrificial protection: Iron coated in a more reactive metal - EG Magnesium is way more reactive than iron so it reacts with air and 'sacrifices' itself protecting the iron An example of sacrificial protection is Galvanising: Galvanising: Iron coated in zinc - Zinc is more reactive than iron so it will react with the air instead of it Tinning: Iron coated in tin -Tin is less reactive and doesn't reactive with oxygen so tin inside is protected
63
Rusting in: 1) Boiled water 2) Salt water 3) Water 4) Air 5) Air + Calcium Chloride
1) Boiled water = no rusting as boiled water has no oxygen in it 2) Salt water = lots of rusting as salt speeds up rusting 3) Water = Rusting as water contains oxygen 4) Air = Rusting as air contains moisture 5) Air + Calcium Chloride = no rusting as calcium chloride dries air removing the water
64
Definitions for properties: - Tensile strength - Compressive strength - Hardness - Brittle
Tensile strength: Ability to withstand stretching without breaking Compressive strength: Ability to withstand compression (squashing) without breaking Hardness: Ability to resist wear, stretching or indentation Brittle: A material that can be easily broken
65
What are ceramics?
A hard non- metallic material made from metals and non metals - they form giant ionic lattices or giant covalent structures
66
Properties of ceramics?
- High melting points - Hard and stiff, but brittle - Poor thermal and electrical conductors - Chemically unreactive as they contain mostly oxides
67
How are glass ceramics made?
Made by melting sand (silicon dioxide) which is allowed to cool into solid
68
How is clay ceramics made and some examples of clay ceramics?
-Brick, china, porcelain Made by heating clay at high temperatures which cause crystals to form and join together. They are often coated in a glaze which hardens on heating to form a hard, smooth, opaque waterproof layer.
69
What are composite materials and some examples of them?
-Concrete, wood and fiberglass Made of 2 components: 1) The reinforcement - materials that make up the bulk of the comospite 2) The matrix - substance binding the composite together
70
How is soda-lime glass made and what are its properties?
Made by heating a mixture of sand, sodium carbonate and limestone PROPERTIES: - Transparent - Doesn't conduct electricity
71
How is borosilicate glass made and what are its properties?
Made from sand and boron trioxide PROPERTIES: -Melts at higher temperature than soda-lime glass
72
Properties of composites?
- light weight | - Insulator
73
Thermosetting polymers vs Thermosoftening polymers
THERMOSOFTENING: consist of individual, tangled polymer chains and melt when heated and can be remolded: the polymer chains can move freely over each other when heated THERMOSETTING: consist of polymer chains with cross-links between them so they don't melt when heated - they are hard and brittle

CHEMISTRY (7 decks)

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