C6-10 Spec Chemistry Flashcards
what 4 things do humans use the earth’s resources for
warmth, shelter, food, transport
what 4 things do natural resources provide
food, timber, clothing fuels
what 2 things are finite resources from the earth, oceans and atmosphere processed to do
provide energy and materials
what is the role of chemistry for helping sustainable development
improving agricultural and industrial processes
to provide new products and promote sustainable development
what is the definition of sustainable development
meeting the needs of current generations without compromising the ability of future generations to meet their own needs
give 2 example of a synthetic product which supplements/replaces a natural one in agriculture
manure - natural fertiliser
replaced by haber process nitrogen fertiliser
rubber can be made naturally from sap but also can be produced synthetically
drinking water needs sufficiently low levels of what 2 things
dissolved salts
microbes
what is water safe to drink called
potable water
is potable water pure chemically
no - it contains dissolved substances
what 2 things can affect the method used to produce potable water
supplies of water
local conditions
what 3 places does rainwater collect?
ground, lakes, rivers
rain water is ____water
fresh
give the method of collecting the majority of potable water in the UK - 3 steps
choose appropriate freshwater source
pass water through filter beds
sterilising
give 3 examples of sterilising agents for potable water
chlorine
ozone
ultraviolet light
if supplies of freshwater are limited then what do you need to do
desalination of salty water or sea water
give 2 methods of desalination
distillation
processes using membranes such as reverse osmosis
why is water passed through filter beds
to remove insoluble particles
why is water sterilised
to kill microbes
how does reverse osmosis work
force water through a membrane which allows water through but prevents most ions travelling through
desalination requires lots of ____
energy
what colour is universal indicator if pH is 7
green
how do you test a substance has dissolved solids
weigh evaporating basin
use evaporating basin over gauze and tripod and bunsen burner
let the basin cool and then reweigh it
calculate the change in mass
explain how to purify a water sample by distillation
heat water gently using a bunsen burner, tripod, gauze and conical flask until it boils
connect the conical flask using a bung and tube to a test tube held in a clamp and in a beaker of ice and water
do alkanes have a double bond
nope - as A is single atm
what does saturation mean
max amount of hydrogens bonded to each carbon
what is crude oil made of
remains of ancient biomass consisting of mainly plankton that was buried in the mud
define hydrocarbon
compound with ONLY hydrogen and carbon atoms
crude oil hydrocarbons are mostly ___
alkanes
what is the homologous series for alkanes and what is the formula
Cn H2n+2
the family - alkanes
what are the first 4 alkanes
methane
ethane
propane
butane
there are many differernt hydrocarbons in crude oil which can be separated into what
fractions
each fraction contains a similar number of ___
carbon atoms
name 5 fuels from crude oil
heavy fuel oil
petroleum gases
kerosene
petrol
diesel
the petrochemical industry produces lots of useful materials for modern life such as what
solvents
lubricants
polymers
detergents
a vast array of natural and synthetic —- atoms occur due to the ability of — atoms to form similar compounds
CARBON
CARBON
describe how fractional distillation works - can do (can skip kind of)
fractionating column
with a temperature gradient
so the top is cooler than the bottom
vaporised crude oil enters the bottom
rises
longest chain hydrocarbons condense near the bottom as they have the highest boiling points
hydrocarbons condense at their boiling points further up
gases which still haven’t condensed at the top of the column leave as a waste product
how can hydrocarbons be broken down to produce smaller more useful molecules
cracking
what are the two ways of doing cracking
steam cracking
catalytic cracking
what are the general conditions for catalytic cracking
vaporise the hydrocarbon
pass it over an aluminium oxide catalyst
cracking breaks ___into ___ (although the products could still be ___
alkane
alkene
alkane
what type of reaction is cracking
thermal decomposition
what are the conditions for steam cracking
vaporise
mix with steam
heat to high pressures
what is more reactive - alkene or alkane
alkene
alkenes can react with ____ which is used to test for alkenes - what is the colour change?
bromine water
orange to colourless
why is cracking useful
there is a high demand for fuels with small molecules and so some of the products of cracking are useful as fuels
alkenes are used to produce what - (as starting materials for the production of many other chemicals)
polymers
properties of long chain hydrocarbons
not flammable
very viscous
high boiling points
burns with a smoky flame
properties of short chain hydrocarbons
flammable
runny - low viscosity
low boil points
burns without smoky flame
what 2 reasons are there for us producing lots of waste water that needs ___before being released into the environment
urban lifestyles
industrial processes
what needs removing from sewage and agricultural waste
organic matter
harmful microbes
what needs removing from industrial waste
organic matter and
harmful chemicals
give the 4 stages of sewage treatment
screening and grit removal
sedimentation to produce sewage sludge and effluent
anaerobic digestion of sewage sludge
aerobic biological treatment of effluent
what is the effluent in sewage treatment
the liquid that remains on top
how is sewage sludge digested
anaerobically
how is effluent digested
aerobically
what 2 things does sedimentation produce
sewage sludge and effluent
the earth’s metal ore stores are ___
limited
what ores are becoming scarce
copper ores
give 2 ways of extracting copper from low grade ores
phytomining
bioleaching
what are traditional mining methods of mining copper ore
digging
moving
and disposing of large amounts of rock
what is phyotmining - don’t describe process
using plants to absorb metal compounds
P = plant
what is the process of phytomining
plants harvested
burned to produce ash that contains metal compounds
what is bioleaching
using bacteria to produce leachate solutions that contain metal compounds
give 2 ways copper can be obtained from a copper compound
displacement using scrap iron
electrolysis
what 4 stages to life cycle assessments take into account in measuring environmental impact
extracting and processing raw materials
manufacturing and packaging
use and operation during lifetime
disposal at end of useful life
transport and distribution at each stage
why is life cycle assessment quantifying not purely objective
allocating numerical values to pollutant effects requires value judgements
HOWEVER
water, resources, energy sources and waste production can be fairly easily quantified
give an example of how selective or abbreviated LCAs can be devised to evaluate a product and misused to reach pre-determined conclusions
advertising purposes
give the LCA for a plastic bag
crude oil is finite + fractional distillation and cracking and polymerisation requires lots of energy
can be reused as stronger
can be recycled
don’t biodegrade
landfill - centuries there
give LCA for a paper bag
can be made from recycled paper
less energy to make a paper bag
more expensive to make bags from paper as handles have to be glued on
short lifetime
can be recycled easily
biodegrade quickly
give an example of a product that can be reused
glass bottles
what can glass bottles be reused for
crushed and melted to make different glass products
give 5 materials produced from limited raw materials
metals
glas
building material s
clay ceramics
most plastics
how are metals recycled
melting
recasting or reforming into different products
what doe the amount of separation required for recycling depend on
material and properties required of the final product
give an example of a form of recycling to reduce the amount of iron that needs to be extracted from iron ore
add iron to scrap steel in a blast furnace
what is corrosion
destruction of materials by chemical reactions with substances in the environment
give an example of corrosion
rusting
what 2 things are necessary for iron to rust
air and water
give 4 ways of preventing corrosion
coating that acts as a barrier
such as greasing, painting or electroplating
give an example of a metal that has a protective coating
aluminium has an oxide coating that protects the metal from further corrosion
what is sacrificial protection
some coatings contain a more reactive metal to provide sacrificial protection
give an example of using sacrificial protection
zinc is used to galvanise iron
most metals in everyday use are___
alloys
what is bronze an alloy of
copper and tin
b = c + t
what is brass an alloy of
copper and zinc
s = z
gold used in jewellery is usually an allow with what
silver, copper, zinc
what is the proportion of gold in the alloy measured in
carats
what is 18 carat gold
75%
what are steels alloys of
iron - with specific amounts of carbon and other metal
what are the 2 properties of high carbon steel
strong but brittle
what are two properties of low carbon steel
softer and more easily shaped
are do stainless steels contain
chromium and nickel
CNS
give 2 properties of stainless steel
hard
resistant to corrosion
give a property of aluminium alloys
low density
give a use for high carbon steels
construction
give a use for low carbon steels
car body panels - as malleable
give a use of stainless steel
cutlery as doesn’t rust
give a use of bronze
statues, bells, coins
give a use of brass
musical instrument making, taps and door knobs
what is most of the glass we use
soda lime glass
how is soda lime glass made
heating a mixture of sand, sodium carbonate, and limestone
what is borosilicate glass made of
sand and boron trioxide
borosilicate glass melts at ___temperatures than soda lime glass
higher
how are clay ceramics made
shaping wet clay
and then heating in a furnace
give 2 examples of clay ceramics
pottery and bricks
what 2 things do the properties of polymers depend on
what monomers made from
conditions under which they are made
what do thermosoftening polymers do when heated
melt
what do thermosetting polymers do when heated
don’t melt
most composites are made of what 2 things
a matrix or diner
binding together fibres or fragments of the other material - the reinforcement
give 3 examples of composites
reinforced concrete
fibreglass
chipboard
what is the matrix for reinforced concrete and what is the reinforcement
matrix = concrete
reinforcement = steel
what is matrix and reinforcement for fibreglass
reinforcement - glass fibres
matrix = polymer resin
matrix and reinforcement for chipboard
matrix - resin glue
reinforcement - wood chips
describe the difference between thermosetting and thermosoftening polymers in terms of structures
thermosoftening - no cross links (covalent bonds between between molecule layers) so molecules can move over each other when heated and therefore melt
thermosetting - cross links (strong covalent bonds between molecule layers - can’t melt when heated)
how is low density poly(ethene) made
moderate temp
high pressure
with a catalyst
how is high density poly ethene made
lower temp and pressure
different catalyst
compared to low density
what is the haber process used for
manufacturing ammonia
what can ammonia be used for
producing nitrogen based fertilisers
what is nitrogen extracted from
the air
what is hydrogen extracted from
natural gas
what temp is haber process at
450 degrees celsius
what pressure is the haber process done at
200 atmospheres
the reaction in the haber process is ____and so some of the ammonia breaks down into ___and ___
reversible
nitrogen and hydrogen
describe the process of the haber process
purified gases passed over an iron catalyst at high temp and pressure (450, 200)
cooled and ammonia is liquefied and removed
nitrogen and hydrogen remaining recycled
what type of catalyst is used in haber process
iron
how is ammonia removed from haber process
liquified
what does equilibrium position on the right mean
there is more of the stuff on the right present in the mixture (as the rate of reaction on the left is higher)
why is 200 atmospheres used in haber process
high pressure to increase ammonia yield - as equilibrium on side with least moles (ammonia side)
but not too high as maintaining that high pressure is expensive
N2(g) + 3H2(g) ⇌ 2NH3(g)
why is the haber process completed at 450 degrees
increase rate of reaction
but trade off between yield and rate
as the forwards reaction is exothermic
so increasing temperature moves equilibrium to the side which is produced by an endothermic reaction (more of the reactants are produced)
decreasing yield of ammonia
N2(g) + 3H2(g) ⇌ 2NH3(g)
how can the reaction being exothermic help reduce costs
excess heat can heat other parts of the process
and can generate electricity
how can recycling hydrogen and nitrogen reduce cost
cost of obtaining raw materials reduced as less needed
how does the catalyst affect reaction
increases rate - of both forward and backward reactions equally
what are the 3 compounds in NPK fertilisers
nitrogen
potassium
phosphorus
NPK fertilisers are formulations of ___
salts
what can ammonia be used for
ammonium salts
nitric acid
give 2 compounds of potassium that are obtained by mining
potassium chloride
potassium sulfate
how is phosphate obtained
phosphate rock is mined - but it can’t be used directly as a fertiliser
how is phosphate made to produce soluble salts that can be used as fertilisers
reacted with nitric acid and sulphuric acid
what is reaction of phosphate rock plus nitric acid
calcium nitrate + phosphoric acid
what is reaction of phosphoric acid and sulphuric acid
single superphosphate (mix of calcium phosphate and calcium sulphate)
what is reaction f phosphoric acid and phosphoric acid
triple superphosphate - (calcium phosphate )
give 2 ions from ammonia and how you can get them
ammonium - neutralisation
and nitrate - oxidation of ammonia
