C6.1: Improving Processes And Products Flashcards
What are the 3 essential elements needed by plants?
Nitrogen
Phosphorus
Potassium
What happens to plants if they are not supplied with the essential elements?
Plants do not grow as well - show signs of mineral deficiency
What are the typical symptoms of deficiency when there is a lack of potassium?
Poor fruit growth
Discoloured leaves
What are the typical symptoms of deficiency when there is a lack of phosphorus?
Poor root growth
Discoloured leaves
What are the typical symptoms of deficiency when there is a lack of Nitrogen?
Poor growth
Yellow leaves
What are fertilisers?
Substances that replace the elements made by plants as they grow
In which state must fertilisers be in
Water-soluble form
Allows plant roots to absorb it
What does water-soluble mean?
Something that can be easily dissolved in water
Why are ions water soluble?
Water is a polar molecule
Positive and negative charges of the water pull apart positive and negative ions
Surrounds the split ions with water molecules, keeping them dissolved
What is a polar molecule?
A molecule with an uneven distribution of charge
What is the ion form of nitrogen?
Nitrate ions
Ammonium ions
What is the formula for nitrate ions
NO3-
What is the formula for ammonium ions
NH4+
What is the ion form of phosphorus?
Phosphate ions
PO4 3-
What is the ion form of potassium?
Potassium ions
K+
What are NPK fertilisers?
Fertilisers that provide nitrogen, phosphorus and potassium in water soluble compounds
What is the Haber process?
A method used to produce ammonia from nitrogen and hydrogen
What is the haber process formula?
N2 (g) + 3H2 (g) <==> 2NH3 (g)
What is ammonia used for?
To make fertilisers
What are the raw materials for the Haber process?
Air
Natural gas
Steam
How do you obtain nitrogen?
Comes from air
78% nitrogen
How do you obtain hydrogen?
Obtained from hydrocarbons such as methane
Why is the Haber Process important?
Ammonia produced - used to make nitrogen based fertilisers
What type of reaction is the Haber Process?
Exothermic
Reversible
What does an exothermic reaction mean?
Produces heat
What does an endothermic reaction mean?
Takes in heat
Why does the haber process have a very high yield?
It recyles back any unreacted raw materials
Reversible reaction
What temp does the haber process use?
450 degrees C
Why does the haber process use 450 degrees C?
Forward reaction is exothermic, so reaction should be done at low temp for high yield
Reaction will be faster at higher temps, more collisions due to more kinetic energy
Generating high temps expensive
450 used as compromise
What pressure is used in the Haber Process?
200 atmospheres
Why does the Haber Process use 200 atm?
High pressure needed to favour forward reaction
Particles collide more frequently
BUT
High pressure is expensive and dangerous
200 is a compromise
What is the approximate yield of the Haber Process?
Around 98%
The haber process considers something else other than temp and pressure. What?
Iron Catalyst
What does an iron catalyst do in the Haber Process?
Speeds up the forward and reverse reaction
No effect on equilibrium
What is a batch process?
Making small amounts of products
What are continuous processes?
Large industrial amounts
What must be done to the raw materials before or after making fertilisers?
Must be purified
How is the rate of production in batch vs continous processes?
Batch: low
Continuous: high
How is the cost of equipment in batch vs continous processes?
Batch: low
Continuous: high
How is the number of workers in batch vs continous processes?
Batch: large
Continuous: small
How is the shut down periods in batch vs continous processes?
Batch: frequent
Continuous: rare
How is the ease of automating in batch vs continous processes?
Batch: hard
Continuous: easy
What are 2 hazards of making fertiliser compounds in a lab?
Release of toxic fumes
Exposure to corrosive chemicals
What is the contact process?
An industrial process used to make sulfuric acid
What materials are needed for the contact process?
Sulfur
Oxygen
Water
What is stage 1 of the contact process?
And include chemical formula
Sulfur burns in oxygen forming sulfur dioxide
S (s) + O2 (g) —> SO2 (g)
Is the contact process exothermic or endothermic?
Exothermic
What is stage 2 of the contact process?
And include chemical formula
Sulfur dioxide reacts with oxygen to form sulfur trioxide
2SO2 (g) + O2 (g) <==> 2SO3 (g)
What are the conditions for stage 2 of the contact process?
450 degrees C
2 atm
Vanadium pentoxide catalyst
What is the yield of stage 2 of the contact process?
About 96%
What is stage 3 of the contact process?
And include chemical formula
Sulfur trioxide is converted into sulfuric acid
H2O (l) + SO3 (g) —> H2SO4 (aq)
Why is a temp of 450 degrees C used in the contact process?
High temp increase the rate of reaction
High temps expensive and decrease the yield as forward reaction is exothermic
The catalyst only works at a temp above 380 degrees C
Why is a pressure of 2 atm used during the contact process?
High pressure inc rate of reaction
High pressure is expensive
Compromise
Why is vanadium oxide used as a catalyst in the contact process?
Used to inc rate of reaction
No effect on yield
What is an ore?
A rock that contains a metal that is enough to be economically viable enough to extract
What are the extraction methods of metals?
Electrolysis
Heat with carbon
How do we know which method of extraction to use?
Depends on reactivity series
Carbon only works when metals less reactive than carbon
What happens to ores after extracting?
Extracted by mining
Processed to separate the metal
Pros of using electrolysis for metal extraction?
Can extract all metals
Cons of using electrolysis for metal extraction?
Expensive
How is copper extracted from its ore? What type of reaction
Redox reaction
Roasted in air to produce copper oxide and sulfur dioxide
Copper oxide heated with carbon to produce carbon dioxide and copper
What is a blast furnace?
Used to extract iron from its ore at a high temp using carbon
How is iron extracted from its ore?
Blast furnace
Raw materials: iron ore from haematite, coke, limestone for purifying
What is stage 1 of producing liquid iron from haematite?
Coke burns in hot air making carbon dioxide
C (s) + O2 (g) —> CO2 (g)
What is stage 2 of producing liquid iron from haematite?
Coke reduces the carbon dioxide making carbon monoxide
C (s) + CO2 (g) —> 2CO (g)
What is stage 3 of producing liquid iron from haematite?
Carbon monoxide reduces Iron (III) oxide to iron at around 1500 degrees C
Liquid iron is formed but there are a lot of impurities which need to be removed
What is stage 1 of removing impurities from liquid iron using limestone?
Calcium carbonate decomposes in high temps
CaCO3 (s) —> CaO (s) + CO2 (g)
What is stage 2 of removing impurities from liquid iron using limestone?
Calcium oxide reacts with silica to form calcium silicate
Called a slag
What is a slag?
Calcium silicate
Why is a slag important for removing impurities?
Floating on top of melted metal and makes a layer
Slag can be scooped off and makes metal clean
What is the limestone formula?
CaCO3
What is coke?
Purified coal used as fuel
Formula: C (s)
What is the aluminium ore called?
Bauxite
By which method is aluminium extracted?
Electrolysis - costly
Aluminium oxide has a melting point of 2072 degrees but thats too expensive to heat. How do we get around it?
Molten cryolite is dissolved with aluminium oxdiee which allows electrolysis to happen at 950 degrees C
What is used as the cathode in extracting aluminium electrolysis?
Graphite lining
What is used as the anode in extracting aluminium electrolysis?
Large graphite blocks
Where is the molten mixture of aluminium oxide and cryolite contained in during the electrolysis of aluminium extraction?
A huge electrolysis cell that is made from steel and lined with graphite
What is produced at the cathode when extracting aluminium?
Aluminium
What is produced at the anode when extracting aluminium?
Oxygem
Reacts with graphite anodes
Making carbon dioxide
Why do the graphite blocks need to be replaced in extracting aluminium electrolysis?
The carbon dioxide formed at the anode wears tem away overtime
What half equation occurs at the cathode in extracting aluminium electrolysis?
Al3+ + 3e- —> Al
What half equation occurs at the anode in extracting aluminium electrolysis?
2O2- —> O2 + 4e-
What is bioleaching?
Using bacteria to extract copper by wearing the rock away
What is phytoextraction?
Growing plants in soil with metal compounds, to be extracted from the plant later
Pros of bioleaching
Low grade copper ore can be used
Cheap
Cons of bioleaching
Slow
Toxic substances
Pros of phytoextraction
Cheaper
Less waste
Carbon neutral activity
Cons of phytoextraction
Slow
Crops need replanting and harvesting for years
What is the process of phytoextraction?
Plants are given a complexing agent to help them absorb mineral ions better
Plants grow, harvested, burned
Ash has a high conc of metal
Metal extracted from ash
What is an alloy?
A mixture of 2 or more elements, where at least 1 is a metal
What is tensile strength?
The resistance of a material to breaking under tension
What is ductility?
Ability to be drawn into wires
Why is an alloy stronger than a pure metal?
Alloys have different sized atoms so when they mix, the smaller atoms distort the layers and make it difficult for them to slide over each other - making them stronger
What are steel alloys made from and what are their properties?
Iron, carbon and other metals
High strength
Ductile
What does it mean when something is corrosive?
Tending to cause corrosion, wearing away, eroding
What are solder alloys made from? Properties?
Tin and lead
Strong
Low melting point
Electrical/thermal conductivity
What are brass alloys made from and what are their properties?
Made of copper and zinc
Resists corrosion
Strength
High electrical/thermal conductivity
Good malleability and ductility
What are bronze alloys made from? Properties?
Copper and tin
Hardness
Ductility
Flexibility
What are duralumin alloys made from? Properties?
Consists of aluminium, containing 4% copper
Soft
Ductile
Light weight
What can solder alloys be used for?
Joining copper pipes and electrical components
What can steel alloys be used for?
Pipelines
Building beams
What can bronze alloys be used for?
Propellers for ships
Bells
What can duralumin alloys be used for?
Aircraft parts
What can brass alloys be used for?
Coins
Musical instrument
What makes a metal strong?
If the layers are hard to slide over each other, the stronger the metal
Why is steel good for making car body parts?
Because it is easily pressed into shape, malleable
What is corrosion?
The destruction of materials by chemical reactions with substances in the environment
What is the word equation for rusting?
Iron + oxygen + water -> hydrated iron (III) oxide
What is the balanced symbol equation for rusting?
4Fe + 3O2 + 6H2O —> 2Fe2O3 . 3H2O (s)
Which physical barriers can be used to prevent oxygen and water needed for rust?
Painting
Oiling and greasing
Coating with plastic
How can electroplating be used to prevent rust?
Putting a thin layer of metal on the object
What is at the anode when electroplating an object?
The plating metal
What is at the cathode when electroplating an object?
Iron or steel object
What is the electrolyte when electroplating an object?
Contains ions of the plating metal
How can sacrificial protection be used to prevent rust?
A corrosion prevention where a more reactive metal is attached to a less reactive metal to prevent the less reactive metal from corroding as the more reactive metal corrodes in its place
How can galvanising be used to prevent rust?
Zinc layer stops oxygen and water reaching the iron
Zinc is more reactive than iron so it acts as a sacrifice
This works even if the zinc is scratched
What is the appearance like of glass ceramics?
Transparent
What is the appearance like of clay ceramics?
Opaque
What is the appearance like of metals?
Shiny
What is the melting point like of glass ceramics?
High
What is the melting point like of clay ceramics?
High
What is the melting point like of metals?
High
Malleable or brittle of glass ceramics?
Brittle
Malleable or brittle of clay ceramics?
Brittle
Malleable or brittle of metals?
Malleable
How is the ability to conduct electricity and heat of glass ceramics?
Poor
How is the ability to conduct electricity and heat of clay ceramics?
Poor
How is the ability to conduct electricity and heat of metals?
Good
How are glass ceramics made?
Made by melting sand and allowing the molten to cool and solidify
How are clay ceramics made?
Brick, china, porcelain
Heating clay to high temps which causes crystals to form and join together. Often coated with a glaze
What is the conductivity like of polymers?
Poor
What is the properties of polymers?
Tough
Flexible
BUT SOMETIMES
Hard
Flexible
Properties of poly(ethene)
Flexible
Cheap
Can be made into thin films
Properties of poly(propene)
Flexible
Strong
Resists shattering
Properties of poly(chloroethene)
Tough
Electrical insulator
Can be made hard or flexible
Properties of poly(tetrafluoroethene)
Slippery
Chemically unreactive
Uses of poly(ethene)
Carrier bags
Shmpoo bottles
Food wrap
Uses of poly(propene)
Buckets
Bowls
Crates
Ropes
Carpets
Uses of poly(chloroethene)
Insulation for electrical wires
Windows
Gutters
Pipes
Uses of poly(tetrafluoroethene)
Non stick coatings for pans
Containers for laboratory substances
What is a composite material?
Made from 2 or more diferent materials combined to improve properties
What are the 2 components of most composite materials?
Reinforcement
Matrix
What is the role of reinforcement in composite materials?
Gives strength to the composite material
What is the role of the matrix in composite materials?
Holds the reinforcement together and binds it
