Using Resources Flashcards
What are ceramics?
Ceramics are non-metal solids with high melting points.
What are 3 examples of ceramics?
- Some ceramics are made from clay
- An example is soda-lime glass
- An example is borosilicate glass
What is clay?
- Clay is a soft material when it’s dug up and can be moulded into different shapes
- When it’s fired at high temperatures, it hardens to form clay ceramics
- It’s ability to be moulded when wet and then hardened makes clay ideal for making pottery and bricks
What is soda-lime glass?
- Soda-lime glass is made by heating a mixture of limestone, sand and sodium carbonate until it melts
- When mixture cools it comes out as glass
What is borosilicate glass?
- Borosilicate glass has a higher melting point than soda-lime glass
- Borosilicate glass is made by heating a mixture of boron trioxide and sand until it melts
- When mixture cools it comes out as glass
What are composites?
- Composites are made of one material embedded in another
- A reinforcement (e.g. fibres, fragments) is surrounded by a matrix acting as a binder
What are four composites?
- Fibreglass
- Carbon fibre
- Concrete
- Wood
What is fibreglass?
What are the properties of fibreglass?
What is fibreglass used for?
*Fibreglass consists of fibres of glass embedded in a matrix made of a polymer (plastic)
* It has low density (like plastic) but is very strong (like glass)
* It is used to make things like: skis, boats, surfboards
What is carbon fibre?
What are the properties of carbon fibre?
What is carbon fibre used for?
- Carbon fibre has a polymer matrix and the reinforcement is made from either long chains of carbon atoms bonded together or from carbon nanotubes
- These composites are very strong and light
- They are used in aerospace and sports car manufacturing
What is concrete?
What are the properties of concrete?
What is it used as?
- Concrete is made from aggregate (a mixture of a sand and gravel) embedded in cement
- It’s very strong
- This is used as a building material e.g. skate parks
What is wood?
Wood is a natural composite of cellulose fibres held together by an organic polymer matrix.
What are two things that can influence that properties of a polymer?
- How it’s made
- What it’s made from
How do different densities change the properties in poly(ethene)?
- Low density (LD) poly(ethene) is made from ethene at a moderate temperature under a high pressure - it’s flexible and is used for bags and bottles
- High density (HD) poly(ethene) is also made from ethene but at a lower temperature and pressure with a catalyst - it’s more rigid and is used for water tanks and drainpipes
What determines the types of bonds that form between polymer chains?
The monomers that a polymer is made from determine the types of bonds that form between the polymer chains. These weak bonds between the different molecule chains determines the properties of the polymer.
What are thermosoftening polymers?
Thermosoftening polymers contain individual polymer chains entwined together with weak forces between the chains - you can melt these plastics and remould them.
(Look how to draw them.)
What are thermosetting polymers?
Thermosetting polymers contain monomers that can form cross-links between the polymer chains, holding the chains together in a solid structure. These polymers don’t soften when they are heated because they are strong and hard and rigid.
(Look how to draw them)
What are the 4 different materials used for?
- Ceramics (including clay and glass) are insulators of heat and electricity, brittle and stiff
- Polymers are insulators of heat and electricity, they can be flexible and are easily moulded
- Composites depend on the matrix/binder and the reinforcement used to make them, therefore, they have many different uses
- Metals are malleable, good conductors of heat and electricity, ductile and have many uses including electrical wires, car body-work and cutlery
How are alloys made?
Alloys are made by adding another element to the metal. This disrupts the structure of the metal making alloys harder than pure metals.
What are 5 different types of alloy?
- Steel - combination of iron and carbon
- Bronze - combination of copper and tin
- Brass - combination of copper and zinc
- Gold alloys - combination of gold and metals such as copper, zinc, silver
- Aluminium alloys - combination of aluminium and other metals
What are the 5 different types of alloy used for?
- Steel - car bodies, bridges, etc.
- Bronze - medals, statues, decorative ornaments (bronze is harder than copper)
- Brass - water taps and door fittings (brass is malleable)
- Gold alloys - used instead of pure gold because pure gold is very soft
- Aluminium alloys - are used to make aircrafts (pure aluminium is too soft)
What is corrosion?
Corrosion is where metals react with substances in their environment and are gradually destroyed. Corrosion only happens at the surface of a metal where it’s exposed to the air.
What metal rusts?
Equation for the rusting?
- Iron corrodes easily and we call this rusting
- Rust is a soft crumbly solid that soon flakes off to leave more iron exposed to rust again
- This eventually means that all the iron in an object corrodes away even if it wasn’t initially at the surface
- Iron + water + oxygen –> hydrated iron(III) oxide
What’s a metal that corrodes but doesn’t get completely destroyed?
Aluminium corrodes when it’s exposed to the air forming aluminium oxide but doesn’t flake away. This forms a protective layer that sticks firmly to the aluminium and stops any further reaction taking place.
What experiment can show that both oxygen and water are needed for iron to rust?
- By putting an iron nail in a boiling tube with just water, it won’t rust (water is boiled to remove oxygen and oil is used to stop air getting in)
- By putting an iron nail in a boiling tube with just air, it won’t rust (calcium chloride can be used to absorb any water from the air)
- By putting an iron nail in a boiling tube with air and water, it will rust
What are 3 barrier methods to prevent iron from rusting?
- Painting/coating with plastic - it is ideal for big and small structures and can be decorative
- Electroplating - this uses electrolysis to reduce metal ions onto an iron electrode, and can be used to coat the iron with a layer of a different metal that won’t be corroded away
- Oiling/greasing - this is used for moving parts (e.g. a bicycle chain)
What is a sacrificial method to to prevent iron from rusting?
- This involves placing a more reactive metal such as zinc or magnesium with the iron
- This means that water and oxygen will react with the sacrificial metal instead of the iron
What is a protection technique to prevent iron rusting including barrier and sacrificial methods?
An object can be galvanised by spraying it with a coating of zinc. The zinc layer is firstly protective but if it’s scratched, the zinc around the site of scratch works as a sacrificial metal.
How do natural resources form?
- Without human input
- Anything that comes from the earth, sea or air
How can these natural products be replaced or improved?
Some of these natural products can be replaced by a synthetic product or improved upon by man-made processes.
What provides conditions where natural resources can be enhanced for our needs?
Agriculture provides conditions where natural resources can be enhanced for our needs. For example the development of fertilisers have meant we can produce a high yield of crops.
What is the difference between finite and renewable resources?
- Renewable resources reform at a similar rate to (or faster than) we use them - for example, timber is a renewable resource as trees can be planted and only take a few years to grow
- Finite resources aren’t formed quick enough to be considered replaceable - finite resources include fossil fuels and nuclear fuels
What are the risks of extracting finite resources?
Mining ores is bad for the environment as it uses loads of energy, scars the landscape, produces lots of waste and destroys habitats.
What are the opportunities of extracting finite resources?
- Many modern materials are made from raw, finite resources
- It is a good as it produces useful products
- Provides local people with jobs and brings money into the area
What is sustainable development?
Sustainable development is an approach to development that takes account of the needs of present society whilst not damaging the lives of future generations.
What is one way of reducing the use of finite resources?
One way of reducing the use of finite resources is for people to use less. This not only reduces the use of the resource but also anything needed to produce it.
What can chemists do to reduce the usage of finite resources to become more sustainable?
Chemists can develop and adapt processes that use lower amounts of finite resources and reduce damage to the environment. For example, chemists have developed catalysts that reduce amount of energy required for certain industrial processes.
What are on way to improve the sustainability of extracting copper?
What are the two ways of doing this?
- A way to improve the sustainability of extracting copper is by extracting it from low-grade ores
- Bioleaching
- Phytomining
- These methods have a much smaller impact however are slow
What is bioleaching?
- Bioleaching is bacteria used to convert copper compounds in the ore into soluble copper compounds, separating out the cooper from the ore in the process
- The leachate (the solution produced by the process) contains copper ions, which can be extracted (e.g. by electolysis) or displaced by a more reactive metal (e.g. scrap iron)
What is phytomining?
- Phytomining involves growing plants in soil that contains copper
- Plants can’t use or get rid of the copper so it gradually build up in the leaves
- The plants then can be harvested, dried and burned in a furnace
- The ash contains soluble copper compounds from which copper can be extracted by electrolysis or displaced using scrap iron
How can we conserve the finite amount of each metal?
- We can conserve the finite amount of each metal by recycling metals
- This uses much less energy
- This cuts down on the amount of waste getting sent to landfill
- This changes the amount of separation required for recyclable metals
How are metals recycled?
Metals are usually recycled by melting them and casting them into the shape of the new product.
How can glass recycling help sustainability?
*Glass recycling can help sustainability by reducing the amount of energy needed to make new glass products and also the amount of waste created when glass is thrown away
* Glass bottles can be reused without reshaping
* Other forms of glass can’t be reused so they are recycled instead (usually the glass is separated by colour and chemical composition before being recycled)
* The glass is crushed and then melted to be reshaped for use in glass products (e.g. bottles, jars, insulating glass wool)
What is a life cycle assessment?
A life cycle assessment looks at every stage of a product’s life to assess the impact it would have on the environment.
What are the 4 stages of the life cycle assessment?
- Getting the raw materials
- extracting raw materials needed for a product can damage the local environment
- extraction can also result in pollution due to the amount of energy needed
- raw materials often need to be processed to extract the desired materials and this often needs large amounts of energy
- Manufacture and Packaging
- manufacturing products and their packaging can use a lot of energy resources and can also cause a lot of pollution
- you also need to think about waste products and how to dispose them
- the chemical reactions used to make compounds from their raw materials can produce waste products
- some waste can be turned into other useful chemicals , reducing the amount that ends up polluting the environment
- Using the product
- the use of a product can damage the environment (e.g. fertilisers can leach into streams and rivers causing damage to ecosystems)
- how long a product is used for or how many uses it gets
- products that require lots of energy to produce but are used for ages means less waste in the long run
- Product disposal
- products often disposed in landfill sites this takes up space and pollutes land and water
- energy is used to transport waste to landfill which causes pollutants to be released into atmosphere
- products might be incinerated (burnt) which causes air pollution
What is a problem with a life cycle assessment?
- The use of energy, some natural resources and the amount of certain types of waste produced by a product over it’s lifetime can be easily quantified but the effect of some pollutants is harder to give numerical values
- A life cycle assessment is not an objective method as it takes into account the values of the person carrying out the assessment meaning the life cycle assessments can be biased
- Selective life cycle assessments only show some of the impacts of a product on the environment can also be biased as they can be written to deliberately support the claims of a company in order to give them positive advertising
What is potable water?
Potable water is water that’s been treated or is naturally safe for human’s to drink. It’s essential for life.
Is potable water pure and why?
Potable water is not pure as it contains lots of dissolved substances other than H2O molecules.
What are 2 things that make potable water drinkable?
- The pH is between 6.5 and 8.5
- There isn’t any other microbes swimming in it
What is a type of fresh water?
Rainwater is a type of fresh water.
What type of water is fresh water?
Fresh water is water that doesn’t have much dissolved in it.
How can water collect when it rains?
When it rains, water can either collect as surface water or as groundwater.
What are some examples of surface water?
- Lakes
- Rivers
- Reservoirs
What are is an example of groundwater?
Rocks called aquifers that trap water underground.
In the UK, what does the source of freshwater depend on?
The source of freshwater depends on the location.
How is fresh water treated?
- Filtration - a wire mesh screens out large twigs etc, and then gravel and sand beds filter out any other (smaller) solid bits
- Sterilisation - the water is sterilised to kill any harmful bacteria or microbes and can be done by bubbling chlorine gas through it or using ozone or ultraviolet light
In dry countries, what is their source of water?
In dry countries (e.g. Kuwait), they use sea water.
What is the name of the process to treat sea water?
Desalination is the name of the process to treat sea water.
How is sea water desalinated by distillation?
- First, test the pH of the water using a pH meter and neutralise it to required pH - you can neutralise it with a titration
- Second, test the water for the presence of sodium chloride (main salt in seawater)
- To test for sodium ions by doing a flame test on a small sample and if sodium ions are present the flame turns yellow
- To test for chloride ions you take another sample and add a few drops of dilute nitric acid followed by a few drops of silver nitrate solution and if chloride ions are present a white precipitate will form
- Third, to distil water, pour salty solution into a distillation apparatus and heat flask from below, the water will boil forming steam leaving any dissolved salts in the flask as the steam condenses back to liquid water in the condenser and can be collected
- Forth, retest the distilled water for sodium chloride to check it has been removed and also retest the pH to check it’s neutral (pH of 7)
When checking the neutralised pH of sea water why should we use a meter instead of an indicator?
We use meters rather than indicators as this won’t contaminate the water.
How is sea water desalinated by membranes?
The sea water is passed through membrane that only allows water molecules to pass through. Ions and larger molecules are trapped by the membrane and are separated from the water.
What are the disadvantages of having to desalinate water?
Desalinating water requires loads of energy. This means that it is really expensive and not practical for producing large quantities of fresh water.
What happens when water is flushed down a drain?
When water is flushed down a drain, it goes into the sewers and towards the sewage treatment plants.
What waste water comes from agricultural systems?
Agricultural systems produce a lot of waste water including nutrient run-off from fields and slurry from animal farms.
Why does sewage from domestic or agricultural sources have to be treated before being put back into freshwater sources?
Sewage from domestic or agricultural sources have to be treated to remove any organic matter and harmful microbes before it can be put back into freshwater sources.
If sewage from domestic or agricultural sources isn’t treated and put back into freshwater sources, what would happen?
It would make freshwater sources very polluted and would pose health risks.
What is an example of an industrial process that produces a lot of waste water that needs to be collected and treated?
An example of an industrial process that produces a lot of waste water that needs to be collected and treated is the Haber Process.
Why does industrial waste water need to undergo additional stages of treatment as well as organic matter?
Industrial waste water need to undergo additional stages of treatment because it contains harmful chemicals.
How do we treat sewage?
- First, the sewage is screened to remove any large bits of material like twigs, plastic bags and grit
- Second, it’s then allowed to stand in a settlement tank and undergoes sedimentation - the heavier suspended solids sink to the bottom to produce sludge while the lighter effluent floats on top
- The effluent in the settlement tank is removed and treated by biological aerobic digestion - this is when air is pumped through the water to encourage aerobic bacteria to break down any organic matter including other microbes in the water
- The sludge from the bottom of the settlement tank is also removed and transferred into large tanks - here it gets broken down by bacteria in the process anaerobic digestion
- Anaerobic digestion breaks down the organic matter in the sludge, releasing methane gas in the process - the methane gas can be used as an energy source and the remaining digested waste can be used as a fertiliser
- For waste water containing toxic substances, additional stages of treatment may involve adding chemicals, UV radiation or using membranes
What is the Haber process used for?
What is the equation for this process?
- The Haber process is used to make ammonia from hydrogen and nitrogen
- N2(g) + 3H2(g) ⇌ 2NH3(g) (+ heat)
Why is the Haber process well suited for an industrial scale?
The Haber process is well suited for an industrial scale as the reactants aren’t too difficult or expensive to obtain.
How does the Haber process work?
- The nitrogen is obtained easily from the air, which is 78% nitrogen
- The hydrogen mainly comes from reacting methane with steam to form hydrogen and carbon dioxide
- The reactant gases are passed over an iron catalyst - a high temperature of 450°C and a high pressure of 200 atmospheres are used
- Because the reaction is reversible, some of the ammonia produced converts back into hydrogen and nitrogen again and it eventually reaches a dynamic equilibrium
- Ammonia is formed as a gas, but as it cools in the condenser it liquefies and is removed - the unused hydrogen and nitrogen are recycled so nothing is wasted
- The ammonia produced can be used to make ammonium nitrate which is a very nitrogen-rich fertiliser
What factors can affect the position of equilibrium for a reversible reaction?
1) Temperature
2) The concentration of a solution or the pressure of a gas
3) Surface area - this changes depending on the size of the lumps of solid
4) The presence of a catalyst
What happens when the position of equilibrium for reversible reaction is affected?
A trade-off between increasing the rate and maximising the yield of a reaction.
The forward reaction of the Haber Process is?
Exothermic.
What happens when you increase temperatures in the Haber Process? What is the problem of not increasing temperatures?
- This means increasing temperatures will move the equilibrium the wrong way (away from ammonia and towards nitrogen and hydrogen) - so the yield of ammonia would be greater at lower temperatures.
- However, lower temperatures means a slower rate of reaction (this means equilibrium is reached more slowly)
Why is the temperature set to 450°C in the Haber process?
It is a compromise between maximum yield and speed of reaction.
What does higher pressures mean in the Haber Process?
This would move the position of equilibrium towards the products since there are 4 molecules of gas on the left-hand side for every 2 on the right - so increasing pressure maximises the percentage yield and also increases the rate of reaction
Why is the pressure set to 200 atmospheres?
To make pressure as high as possible without making the process too expensive or too dangerous to build and maintain.
How did farmers used to fertilise fields?
With manure.
Why are formulated fertilisers better?
- They are more widely available
- Easier to use
- They don’t smell
- They have just enough of each nutrient so more crops can be grown
What are the 3 main essential elements in fertilisers? What happens if plants don’t get enough of these elements?
1) Nitrogen
2) Phosphorus
3) Potassium
If plants don’t get enough of these elements, their growth and life processes will be affected.
What do fertilisers do?
Replace missing elements in the soil or provide more of them. This helps to increase crop yield as the crops can grow faster and bigger.
What are NPK fertilisers?
They are formulations containing salts of nitrogen, phosphorus and potassium in the right percentages of the elements.
How is nitric acid formed?
When ammonia is reacted with oxygen and water in a series of reactions.
How is ammonium salts formed?
When ammonia is reacted with acids (including nitric acid)
What is ammonium nitrate?
Ammonia and nitric acid reacted together. This is an especially good compound to use in a fertiliser because it has nitrogen from 2 sources.
What is the ammonium nitrate reaction?
NH3 + HNO3 —> NH4NO3
Where is it carried out?
There are 2 ways:
1) In Industry - the reaction is carried out in giant vats at high concentrations resulting in a very exothermic reaction ; the heat released is used to evaporate water from the mixture to make a very concentrated ammonium nitrate product
2) In the Lab - the reaction is carried out on a much smaller scale by titration and crystallisation ; the reactants are at a much lower concentration than in industry so that less heat is produced by the reaction and it’s safer for a person to carry it out ; after the titration, the mixture then needs to be crystallised to give pure ammonium nitrate crystals
Why is crystallisation not used in industry?
Crystallisation isn’t used in industry because it is very slow.
How can potassium chloride and potassium sulphate be gathered and what can they be used for?
Extracted by mining and are used as a source of potassium.
How is phosphate rock gathered and what is the problem with it?
By mining however plants can’t use them as nutrients because the phosphate rocks in them are insoluble.
How can you react phosphate rock with to make phosphates soluble?
1) A reaction with nitric acid produces phosphoric acid and calcium nitrate
2) A reaction with sulphuric acid produces calcium sulphate and calcium phosphate (this mixture is known as single superphosphate)
3) A reaction with phosphoric acid only produces calcium phosphate (the product of this reaction can be called triple superphosphate)
