C6.1 Flashcards
What are the three essential elements for plants
Nitrogen, Phosphorus and potassium
Sign of each deficiency
Nitrogen - poor growth, yellow leaves
Phosphorus - poor root growth, discoloured leaves
Potassium - poor fruit growth, discoloured leaves
What do fertilisers do
They replace the elements used by plants as they grow.
What is the haber process equation
N2 + 3H2 −⇀ 2NH3
Where are the raw materials for the Haber process got from
Nitrogen from the fractional distillation or liquefaction or air
Hydrogen from the reacting of natural gas with steam
How can potassium sulphate and ammonium sulphate be made in the laboratory
H2SO4 + KOH you can perform a titration and add activated charcoal to remove phenolphthalein indicator
NH3 + H2SO4 you can perform a titration on it again and add phenolphthalein again and use charcoal to remove it
What colour is phenolphthalein in acid
colourless
Difference between a batch process and continuous process
batch process - small amount made
Continuous process - make large amounts and go on all the time
Chosen conditions for the Haber process
20 MPa
Temperature of 450 degrees
Iron catalyst
Why are these conditions chosen
Hazardous and expensive to choose a very high pressure. High equilibrium yield would not justify additional costs and pressure is chosen as a compromise.
Temperature chosen as it’s low enough to achieve reasonable rate of reaction and a reasonable equilibrium yield and iron catalyst work more efficiently at > 400 degrees.
What three materials are needed to make sulfuric acid
Sulfur, air and water
What is stage 1 to make sulfuric acid?
Sulfur burns in air producing sulfur dioxide
S + O2 -> SO2
What is stage 2 to make sulfuric acid?
Sulfur dioxide burns in air producing sulfur trioxide
2SO2 + O2 <-> 2SO3
Conditions chosen for stage 2
It’s a reversible reactions so a pressure of 200 kPA is chosen, a temp of 450 degrees and a vanadium oxide catalyst is chosen. 96% yield in these conditions
What is stage 3 to make sulfur trioxide
SO3 + H2O -> H2SO4
What is the precaution taken in step 3 and why
The precaution is that the reaction is extremely exothermic and produces a hazardous mist so is done in two steps.
H2SO4 + SO3 -> H2S2O7 (oleum)
H2S2O7 +H2O -> 2H2SO4
What are the two ways ethanol can be produced
Ethanol can be produced through fermentation or hydration of ethene
Chemical equation of fermentation and conditions chosen
C6H12O6 -> 2CO2 + 2C2H5OH
yeast cells become denatured at high temps and rate of the reaction is low at low temps so 35 degrees is chosen
Is hydration of ethene renewable or non renewable
It is non-renewable as ethene is involved
Chemical equation of hydration of ethene and conditions chosen
C2H4 + H20 <-> C2H5OH
needs a temperature of 300 degrees, a pressure of 60,000 KPa and a phosphoric acid catalyst
What is an ore
An ore is a rock or mineral that contains enough metal to make it economical to extract the metal - value of metal is more than cost of extracting it
What does the method to extract a metal depend on
The position of the metal in the reactivity series
How are copper and iron extracted
Copper and iron are extracted by the heating of it with carbon or with carbon monoxide
How can copper be extracted from copper sulphide
2Cus + 3O2 -> 2CuO +2SO2
2CuO + C -> 2Cu + CO2
Copper oxide is reduced, carbon is oxidised
How is iron extracted from is ore
Using a blast furnace
How does a blast furnace work
Raw materials are added to the top of the blast furnace:
Iron ore such as haematite contains iron (III) oxide
Coke
Limestone which is used to purify the iron
Processes that happen in a blast furnace
carbon reduces iron (III) oxide to iron.
Step 1: coke burns in hot air making CO2.
C + O2 -> CO2
Step 2: more coke reduces the CO2 making CO
C + CO2 -> 2CO
Step 3: Carbon monoxide reduces iron oxide to iron at 1500 degrees celsius
3CO + Fe2O3 -> 3CO2 + 2Fe
what happens to the products of the blast furnace
molten iron trickles down the blast furnace where its impurities are removed using calcium carbonate
Processes that occur to purify the iron
Calcium carbonate decomposes at high temperatures
CaCO3 -> CaO + CO2
Calcium oxide forms which reacts with silica from sandy impurities to form calcium silicate.
CaO + SiO2 -> CaSiO3
The calcium silicate is then collected as slag which floats on top of the molten iron.
How does aluminium exist naturally as
Aluminium exists naturally as aluminium oxide Al2O3. It’s found in an ore called Bauxite. It’s more reactive than carbon so it has to be extracted through electrolysis.
Why is aluminium oxide dissolved in molten cryolite
To reduce the boiling point of aluminium oxide and allowing electrolysis to happen as it’s a liquid.
What is the anode and cathode and what are the reactions that occur there
The graphite lining acts as the cathode and a series of large graphite blocks as the anode.
Aluminium is produced at the cathode
Oxygen is produced at the anode
Al 3+ + 3e- -> Al - cathode
2O2- -> 2O2 + 4e-
what is bio-leaching
When bacteria oxidises iron (II) and sulphide ions using the energy transferred. The sulphuric acid produced breaks down copper sulphide ores and other minerals releasing copper (II) ions and other metal ions
Advantages and disadvantages of bioleaching
It’s cheaper than traditional mining and processing. It allows metals to be extracted from ores that contain too little metal for traditional methods to be profitable. The bacteria occur naturally and don’t release harmful substances.
However, sulphuric acid is produced which is a negative.
What is phyto-extraction
Phyto-extraction is when plants absorb dissolved ions through their roots. A crop is planted on soil with low grade ore. A complexing agent may be added so plants can absorb metal ions more easily. The plants are harvested and then burnt to produce ash with a high concentration of metal which is then extracted.
Advantages and disadvantages of phyto-extraction
Is cheaper than traditional mining and processing. It produces less waste and involves smaller energy transfers. It may need replanting and harvesting for several years before available metal is removed from the soil. However, it’s carbon neutral and sustainable.
What is an alloy
An alloy is a mixture of two or more elements at least one of which is a metal.
Different alloys, what they are made from and typical uses
Steel - iron, buildings, bridges, cars
Solder - tin and copper, joining electrical components and copper poles
Brass - copper and zinc, musical instruments and coins
Bronze - copper and tin, bells and propellors for ships
What is solder and why is it useful
Melting point of 227 degrees. Makes it useful for joining electrical components without damaging them. Hot solder in the liquid state flows into faps between and solidifies quickly. Metals are good conductors.
What is bronze and why are they useful
Alloys are stronger and harder than individual metals they contain. Brass is like this. Copper and zinc atoms are of different sizes and it makes it more difficult for copper atoms to slide over each other.
What is brass and why are they useful
Brass resists corrosion, it doesn’t conduct electricity very well, making it suitable for pins of electric plugs
What is corrosion
Corrosion is the reaction of a metal with substances in its surroundings like air and water.
How does silver get corroded
Silver doesn’t react with the oxygen in the air but does erode in the presence of hydrogen sulphide. It reacts with silver producing a layer of black silver sulphide.
What is rusting
Rusting is a redox reaction. Iron is oxidised to hydrated iron (III) oxide when it reacts with oxygen and water.
iron + water -> hydrated iron (III) oxide
Rusting can continue until the material has been fully eroded.
How to prove rusting
One nail in a test tube with boiled water (water + no air)
One nail in a test tube with anhydrous calcium chloride (no water + air)
One nail in a test tube with water and air (rusting present)
How to reduce corrosion
Many of the methods of rust prevention rely on stopping air and water reaching the surface of the metal:
.Painting .Coating with oil, grease or plastic .Plating with zinc .Plating with tin
What is sacrificial protection
Sacrificial protection involves a metal that is more reactive than iron, such as magnesium or zinc. As long as the iron or steel object is in contact with it, the more reactive metal corrodes first. This method is useful where painting is difficult.
What is metal plating
A layer of metal is placed onto an iron or steel object preventing air and water reaching the steel or iron below.
What is galvanising
Galvanising involves the dipping of the metal object in molten zinc. After it has cooled and solidified the layer of zinc does two things:
1) Stops air and water reaching the iron or steel below
2) Acts as a sacrificial metal so that the object is protected even if the zinc layer is damaged
What is tin plating
The metal is dipped into molten tin, covering it and protecting it from contact with air and water however it’s less reactive so doesn’t prevent rusting.
What are ceramics
Ceramics are hard non metallic materials. Brick, china, porcelain and glass are all ceramic materials. Ceramic materials are non metals combined to form giant ionic lattices or giant covalent structures. Properties of ceramics:
. High melting points
. Hard and stiff but brittle
. Poor conductors of electricity and heat
. Unreactive
What is used for overhead cables and why
Aluminium is used for overhead cables for it as it has a high tensile strength, the lowest density and a good conductivity
What is used as electrical insulators
Porcelain is the most suitable insulator as it has a good electrical resistance, a good tensile strength and a medium compressive strength.
What are composite materials
Composite materials are made from two or more materials combined together each with different properties of the materials it contains. For example it may be stronger, less dense or cheaper.
What do many composite materials consist of
they consist of fibres embedded in polymer resin. The fibres have a low density and tensile strength but are brittle whereas resin is hardwearing but isn’t strong. The composite material is lightweight, strong and hard.
What does concrete consist of and properties
Concrete is a composite material that consists of aggregate (small stones), sand and cement. When water is added chemical reactions happen binding the ingredients together. Concrete has a high compressive strength useful for foundations. Low tensile strength so beams crack. By embedding steel rods in concrete you get steel reinforced concrete with a high compressive and tensile strength
What does plywood consist of and it’s properties
Plywood is made up of wood glued together it’s resistant to 90 degree bends and is useful for floors and walls
What is a life cycle assessment
A life cycle assessment is the impact of making, using and disposing of a manufactured product that should be considered when choosing materials. It includes data about
.Sustainability including the use of raw materials and energy
.Environmental impact, including waste products and pollution
.The lifespan of the product and whether it can be recycled
.Disposal, including how easily materials decompose
What happens if objects can’t be recycled
Unless they can be recycled most materials and products end up in landfill sites as waste. This is not an efficient use of resources,
Reasons to recycles
Conserving limited raw materials and energy resources
Reducing the release of harmful substances into the environment
Reducing waste
Whether are material should be recycled depends on what factors
How costly the waste can be collected and sorted
The amount and type of any by products released by recycling
The cost of recycling compared to landfill or incineration
The amount of energy involved in each stage
How does recycling occur
Waste materials and products must be collected and transported to a recycling plant. These materials have been previously sorted, but further sorting is done at the plant. It is important to ensure that materials aren’t contaminated by other materials. The waste is then shredded or cut into small pieces ready for processing.
How does recycling occur during processing
Metals are melted by heating and molten metals are poured into moulds to produce new blocks called ingots
Paper is mixed with water, cleaner and rolled and heated to make new paper
Glass is melted by heating and moulded into new glass objects
Polymers like pol (ethene), PE4 and poly (propene) are melted and formed into new objects
