using resources excl water Flashcards
clay ceramics:
1) how made
2) 2 examples
+ what are ceramics
ceramics are non metal solids, high melt points no carbon
1) made by digging up soft, wet clay. this is easily moulded. fired in a furnace at high temperatures, hardens to form clay ceramic.
2) POTTERY AND BRICKS
glass (ceramic):
2 types
how each made
common?
difference
use
soda-lime glass; heating limestone, sand, and sodium carbonate until it melts. cools and forms glass. glassware- cups
borosilicate glass: heat a mixture of sand and boron trioxide until it melts. cools and forms glass. less common. higher melting point. test tubes
general physical properties of ceramics
glass AND clay:
1) insulators of heat and electricity
2) brittle (hard but not flexible and break easily)
3) stiff
composites:
how made
what are they
what do properties depend on
1) made when fibres or fragments of a material (reinforcement) are surrounded by a material known as a matrix acting as a binder. one material embedded
2) materials made up of two materials
3) Their properties depend on the properties of the reinforcement and matrix/binder. properties vary
4 examples of composite, reinforcement & matrix, properties, use
- Fibreglass- composed of fibres of glass embedded in a polymer matrix. low density (plastic), strong (glass) . surfboards
- carbon fibre- reinforcement is long carbon chains bonded together or carbon nanotubes embedded in a polymer matrix. strong and light so used in racing cars. high strength to weight to ratio
- concrete- reinforcement of an aggregate (sand or gravel usually) and matrix is cement. strong so used in building material. skate parks
- wood- natural composite of cellulose fibres as reinforcement surrounded by an organic polymer matrix
what do the properties of the polymer depend on + general properties
properties depend on the monomer that they are made from and how they are made.
generally: insulators of heat and electricity, can be flexible and easily moulded
many applications
how are low density poly(ethene) LDPE and high density poly(ethene) made.
arrangement of both and melting point
LDPE made from ethene monomers at high pressures, moderate temp and low availability of o2. bags
HDPE from ethene monomers at a lower temperature and pressure + catalyst. hard hats, crates
both thermosoftening
LDPE is flexible, polymer chains are separated therefore intermolecular forces are low so less energy to overcome these, low melting point.
HDPE is rigid as polymer chains are tangled closely together. greater intermolecular forces so more energy to overcome which means it has a higher melting point
thermosetting vs thermosoftening polymers
thermosetting: monomers that form cross links between individual polymer chains, holding the polymer in a solid structure. don’t soften and don’t melt when heated, burn. held together by strong covalent bonds (cross links)
thermosoftening: individual polymer chains entwined with other chains, weak intermolecular forces between chains. no cross links just tangled chains. when heated, soften and melt and remould.
alloys: explain what happens
mixture of 2 or more metals, one of which is a pure metal
different size metal atoms disrupt metallic lattice, harder for layers to slide over.
harder
most metals in everyday use are alloys
3 types of steel: name, properties, uses
iron + carbon
low carbon steel (0.1-0.3%)- easily shaped- car bodies
high carbon steel (0.2-2.5%)- hard, strong, brittle- blades in cutting tools
stainless steel (chromium and nickel added)- corrosion resistant and cutlery, containers
alloys:
bronze
brass
gold alloys + carat system
aluminium alloys
metals used, uses
bronze- copper and tin; hard- medals, ornaments and statues
brass- copper and zinc. malleable, taps, instruments
gold alloys- gold + (copper,zinc,silver) hardens. jewellery. 24 carat pure gold. find out % of gold by carat no/24 * 100. 18 carat is 75% gold 18/24 *100.
aluminium alloys- alloyed to harden. aircraft manufacture. aluminium low density which is good for aircraft
corrosion:
1) what is it
2) what is rusting and what is needed
3) equation
1) destruction of metals/materials through chemical reactions with their environment. surface of material that is exposed
2) rusting is an example of corrosion. iron only. need air and water.
3) iron + oxygen + water -> hydrated iron oxide
rusting in iron vs corrosion in aluminium
when iron rusts, pieces of iron on surface flake away and more iron exposed. all iron eventually corrodes away
aluminium corrodes to form an oxide layer over it. this acts as a protective layer and stops any further corrosion so aluminium remains intact.
experiment for rusting + mass change of rusty nail
put an iron nail in a boiling tube. in one boiling tube put boiled water (remove o2) and oil (prevents oxygen coming in), in another test tube add calcium chloride (which will absorb any water from air) and in the final one add water and air.
leave for a week
one with water and air will rust, other 2 will not. mass of rusty nail will increase
what is barrier method and 3 ways- corrosion
prevents rusting as iron is coated to keep out h20 and o2.
painting/plastic coat.
electroplating- use electrolysis to reduce metal ions of a different metal that wont be corroded which coats iron.
oiling/greasing- reduce friction on moving parts.
what is sacrificial method
placing a more reactive metal such as zinc to galvanise iron. water and oxygen then react with the more reactive metal instead of iron
how do humans use Earth’s resources
what do natural resources supplemented by agriculture provide examples
where do finite resources come from and what do they provide examples
natural products that are supplemented or
replaced by agricultural and synthetic products
for warmth, shelter, food, transport
food, timber, clothing, fuels. come from air, sea and earth - cotton. timber, food
come from ocean and atmosphere and provide energy and materials . ores, nuclear fuels (uranium and plutonium) and fossil fuels (coal, oil and gas)
rubber from tree sap replaced by rubber made from polymers (tyre), fertiliser supplements agriculture as higher crop yields.
what is sustainable development and how can chemistry help (3)
sustainable
development, which is development that meets the needs of current
generations without compromising the ability of future generations
to meet their own needs.
chemistry can improve agricultural and industrial processes to provide new products like fertilisers developing catalysts which reduce energy input in a chemical reaction + try to reduce waste (biodegradable)
earths levels of metal and copper ores
how can copper ores be extracted sustainably
criticism
Earth level of metal ores and copper ores are becoming more scarce
sustainable methods move away from mining and can be done in 2 ways, extract from low grade ore
phytomining: growing plants in soil which contains copper. plants take up copper but don’t use it so copper builds up in leaves. harvested, dried and burned in furnace. ash contain soluble copper compounds, extracted by electrolysis or a displacement reaction with scrap iron/ more reactive metal
bioleaching: bacteria convert copper compounds into leachate solution that contains soluble copper ions, extracted by electrolysis or a displacement reaction with scrap iron/ more reactive metal
slow process
ALSO USED FOR OTHER METALS
what is an LCA and 4 stages
Life cycle assessments (LCAs) are carried out to assess the
environmental impact of products in each of these stages:
* extracting and processing raw materials- processed with enerfy
* manufacturing and packaging- transport to centres
* use and operation during its lifetime- poollution released (air, water)- reused?
* disposal at the end of its useful life, including transport and
distribution at each stage (landfill)
LCA for paper and plastic bag
**Plastic carrier bags **
**Raw materials **Crude oil is a finite resource;
Manufacture fractional distillation, cracking and polymerisation all require a lot of energy. Cheaper to make large quantities of bags from plastic.
Use Lower impact on the environment because plastic bags are usually stronger so they can be reused many times.
**Disposal **Can sometimes be collected and recycled; if disposed of as litter, they do not biodegrade; in landfill, may take decades or centuries to degrade. pollute land
Paper carrier bags
Raw materials- Can be made from recycled paper, or from trees. Making paper from trees requires more energy than recycling paper, but much less than making plastics. renewable. but deforestation and co2
manufacture- More expensive to make bags from paper because the handles must be glued on. and processing timber = lots of waste
Use- Relatively short lifetime; can only be reused a limited number of times.
**Disposal- ** Can be recycled easily; if disposed of in landfill, they biodegrade quickly. non-toxic
plastic take less energy and have a longer lifespan so may be less harmful to environment
issues with LCAs (3)
- some can be easily quantified with data and numbers like water / waste, but others like pollution can’t
- LCA subjective as opinioon of assessor is taken into account - not objective
- selective LCA only show some ipmacts- used to deliberately support a company/organisation
what does the reduce, reuse, recycle scheme do
why important
reduces the use of limited resources, use of energy sources, waste
and environmental impacts
metals, glass, clay ceramiccs, polymers and composites and building materials come from limited raw materials from earth. obbtaining these by mining or quarrying causes damage. recyling is less energy intensive as manufacture and conserves resource.
how is glass sustainably used
can be re used without reshaping
can be recycled: crushed and melted and reformed to make glass or something else
how are metals recycled + scrap steel specific rule
by melting and recasting. the amount of separation required depends on materials and properties of final product
scrap steel can be added into a blast furnace to reduce the amount of iron ore required
HABER PROCESS:
purpose
reaction
where reactants sourced from
produce ammonia and ammonia based fertiliser.
N2 + 3H2 ⭇ 2NH3
N2 sourced from air (fractional distillation)
H2 sourced from reacting methane and steam (steam cracking of methane) to form h2 and co2
reaction diagram explained for haber
h2 and n2 in
pass over trays of iron catalyst
gas condensed
liquid ammonia collected
unused h2 and n2 are recycled
reaction condition for haber link to dynamic equilibrium
- 450c temp - forward reaction exothermic, so high temp = low yield (equilibrium moves to endothermic direction so more n2 and h2) but high temp = fast ror so compromise at 450.
- conc of n2 and h2 high as liquid ammonia collected continually and reactants always pumped in
- 200 atm pressure- high pressure = fast ror and high yield (moves to side with fewest gas molecules NH3) but high pressure dangerous and expensive (need high pressure tank)
- iron catalyst- alternate pathway lower ea. means lower temp can be used which increase yield. also increase ror
what are NPK fertilisers made from and why good
Compounds of nitrogen (protein) , phosphorus (root growth) and potassium are used as fertilisers to improve agricultural productivity. replaces nutrients that have been taken up by previous crop.
better than manure
how to produce nitratets for NPK + industrial and lab process
ammonia (haber) + nitric acid -> ammonium nitrate
nh3 + hno3 -> nh4no3
industrial = large vats, high concentration. exothermic reaction. heat released evaporates water from mixture to make ammonium nitrate. ammonia + water + oxygen -> nitric acid. nitric acid + ammonia -> ammonium nitrate.
lab = titration (nh3 and hno3) and crystallisation. lower concentration so safer
how are phosphate ions and potassium ions for NPK obtained.what is wrong with source of phosphates
potassium chloride/sulphate mined as a source of potassium ions
phosphate rock (contains phosphorous and calcium) mined- but this is insoluble so plants can’t use them, react with acids to make soluble phosphates.
products when phosphate rock reacted with nitric acid, sulfuric acid and phosphoric acid
nitric acid + phosphate rock -> phosphoric acid + calcium nitrate
sulfuric acid + phosphate rock -> calcium sulphate and calcium phosphate single superphosphate
phosphoric acid + phosphate rock -> calcium phosphate- triple spuerphosphate - Ca3(PO4)2
