Topic 9 Flashcards
(44 cards)
1
Q
what do you use the flame test to identify
A
metal ions
2
Q
what colour do the metal ions go in the flame test
A
lithium - red sodium - yellow potassium - lilac calcium - red-orange copper - blue-green
3
Q
how do you carry out flame test
A
clean a nichrome wire loop by dipping it into hydrochloric acid and rinsing it in distilled water
dip wire loop into metal compound and put in clear blue part of flame
4
Q
what is the test for metal hydroxides other than flame
A
add sodium hydroxide to metal compound and a precipitate will form because some metal hydroxides are insoluble aluminium - white colourless in excess calcium white copper blue iron 2 green iron 3 brown
5
Q
what is the test for ammonia
A
add sodium hydroxide
gently heat
damp red litmus blue
6
Q
what is the test for halide ions
A
dliute nitric acid and silver nitrate
chlorine white
bromine cream
iodine yellow
nitric acid added first to get rid of any carbonate ions - they produce a pale precipitate with silver nitrate too which would confuse the results
you cant use HCl because you would be adding chloride ions
7
Q
what is the test for carbonates
A
add dilute hydrochloric acid
mixture fizz because carbonate react with acid to form CO2
gas produced bubble through lime water and turn cloudy
8
Q
what is the test for sulfate ions
A
add dilute HCl to stop ant precipitate reactions not involving sulfate ions from taking place and barium chloride
white precipitate will form of barium sulfate
9
Q
what is flame photometry
A
- accurately identify different metal ions in a solution and their concentration
- instrumental method allowing you to identify ions in a solution
- each ion produces a unique line spectrum
- the intensity of the measured wavelength indicated the concentration of that ion in solution
- work out conc from a calibration curve
- it can be used to identify different ions in mixtures making it more useful than flame tests which only work for substances that contain a single metal ion
10
Q
what are the advantages of using instrumental analysis like flame photometry
A
- very sensitive and can detect even the tiniest amounts of substances
- n very fast and tests can be automated
- very accurate as it removes human error
11
Q
what are alkanes
A
- homologous series of hydrocarbons
- formula CnH2n+2
- saturates
- orange in bromine water
12
Q
what are alkenes
A
- homologus series of hydrocarbons with one C=C functional group
- formula CnH2n
- unsaturated as can make more bonds as the double bond can open up
- colourless in bromine water as addition reaction takes place where bromine is added across the alkene double bond
13
Q
what happens to hydrocarbons in combustion reactions
A
- they are oxidised
- alkanes and alkenes burn in oxygen in combustion reactions
- during complete combustion they’re oxidised to form carbon dioxide and water
ethane + oxygen -> carbon dioxide and water
ethene + oxygen -> carbon dioxide and water
14
Q
what is addition polymerisation
A
- polymers are substances of high average relative molecular mass made by joining small repeating units called monomers together
- the monomers that make up addition polymers have a double covalent bond
- lots of unsaturated monomer molecules (alkenes) can open up their double bonds and join together to form polymer chains. this is called addition polymerisation
15
Q
what are the uses of polymers
A
poly(ethene):
plastic bags, bottles, wire insulation
poly(propene):
crates, garden furniture, ropes
poly(chloroethene) (PVC):
window frames and water pipes
poly(tetrafluroethene) (PTFE):
nonstick pans and waterproof clothing
16
Q
why are the properties of polymers
A
poly(ethene)
flexible, cheap, electrical insulator
poly(propene)
flexible, strong, trough and mouldable
poly(chloroethene)
tough and cheap
poly(tetrofluroethene)
unreactive, tough and nonstick
17
Q
what is condensation polymerisation
A
- usually involves two different types of monomer
- the monomers react together and bonds form between them making polymer chains
- each monomer has at least two functional groups one on each end of the molecule
- each functional group can react with the functional group of another monomer creating a long chain of alternating monomers
- for each new bond that forms a small molecule (water) is lost
18
Q
what are polyesters
A
- polyesters form when diacarboxylic acid monomers and diol monomers react together
- the diacarboxylic monomers contain two COOH groups (carboxylic acid groups)
- the diol monomers contain two alcohol (OH) groups
- when the carboxylic acid group reacts with the alcohol group it forms an ester link
- polyesters and condensation polymers
- each time an ester link is formed a small molecule of water is lost
19
Q
what are three naturally occurring polymers
A
DNA:
- contains two strands and each strand is made up of nucleotide monomers that bond together in a polymerisation reaction
- bases are different 4 nucleotide monomers
Proteins:
- made from amino acid monomers via condensation polymerisation
Starch and Cellulose:
- Carbohydrates are molecules containing carbon, oxygen and hydrogen used by living things to produce energy
- starch and cellulose are large, complex carbohydrates which are made up of many smaller units of carbohydrates known as sugars joined together in a long chain
20
Q
what are polymers
A
p- plastics are a type of polymer made from crude oil
- crude oil is finite
- the more we use crude oil the more expensive it will become increasing the price of crude oil products
- crude oil is needed for petrol and heating are homes
- one way to fight this problem is recycling
21
Q
discuss the problem of disposal of polymers
A
landfills:
- when polymers are too difficult or expensive to separate and recycle
- lots of valuable land used up quickly
- most polymers are non-biodegradable (not broken down by microorganisms) meaning they will sit in landfills for years
combustion:
- burning plastics produces a lot of energy which can be used to generate electricity
- if not carefully controlled toxic gases can be released from the combustion of plastics. For example when polymers that contain chlorine such as PVC are burned they produce HCl which has to be removed
- carbon dioxide produced contributing to global warming
22
Q
what are the advantages of recycling polymers
A
- reduces the amount of non-biodegradable waste filling up landfills
- avoid environmental impact of burning/landfills
- limit the amount of crude oil we are using
- reduces emissions of greenhouse and toxic gases which can be released from burning polymers
- recycling generally uses up less water and energy resources than when making new plastics
- recycling generally saves money and creates jobs
23
Q
what are the disadvantages of recycling polymers
A
- must be separated by type before they can be melted and reformed into a new product which can be difficult and expensive
- if polymers are mixed together the quality of the final recycled polymer product could be reduced
- polymers can only be recycled a finite number of times
- over time the strength of the polymer can decrease
- melting down polymers can release dangerous gases into the atmosphere
- these are harmful to plants and animals
24
Q
what are the properties of alcohols
A
- general formula CnH2n+1OH
- can be oxidised to form carboxylic acids
- OH functional group
25
discuss alcohols be oxidised to form carboxylic acids
- you need an oxidising agent
- general formula Cn-1H2n-1COOH
- COOH functional group
26
discuss making ethanol by fermentation of yeast
- using yeast to convert sugar into alcohol
C6H12O6 -> 2C2H5OH + 2CO2
glucose -> ethanol + carbon dioxide
- sugar cane and sugar beet plants used
- yeast cells contain an enzyme to speed up reaction as biological catalyst
- mix yeast and glucose solution in clean container
- seal the container and leave in warm place
- keep mixture between 30-40 degrees as enzyme controlled reaction
- keep mixture in anaerobic conditions with no oxygen because otherwise the oxygen oxidises the ethanol to ethanoic acid which tastes vinegary
- when conc of alcohol reaches about 20% the fermentation reaction stops because the yeast is killed off by the alcohol
- yeast will fall to the bottom of the container and you can collect the ethanol solution from the top
- the fermented mixture can be distilled to produce a more concentrated alcohol
27
what is used to concentrate ethanol
fractional distillation
- a dilute solution of ethanol is produced by fermentation
- to make a conc above 20% ethanol must be concentrated by fractional distillation of the fermenting mixture
- fractional distillation separates mixtures by heating them
- ethanol has a lower boiling point than water so when the fermentation mixture is heated ethanol evaporates and vapour rises up the fractionating column while the water stays as a liquid
- a liebig condenser is used to condense the ethanol vapour by cooling it and the concentrated ethanol can then be collected in a separate flask
28
discuss alcohols been used as fuels
- alcohols can be used for fuel because when they are burned they release energy
- some countries that have littler or no oil deposits but plenty of land and sunshine grow loads of sugar cane which they ferment to ethanol and this ethanol is then used to help fuel cars
29
discuss the experiment to see which alcohol is the most efficient
- put 20ml of alcohol in a spirit burner and measure the mass of burner and fuel using a mass balance
- measure 100cm cubed distilled water into copper calorimeter
- insulate calorimater using a draught excluder then cover with an insulating lid after placing a thermometer inside to help reduce energy loss to the surroundings
- take the initial temperature of the water then put the burner under the calorimeter and light the wick
- stir the water throughout using the thermometer. When the heat from the burner has made the temperature of the water rise by 20 degrees blow out the spirit burner
- immediately reweigh the burner and fuel
- repeat the experiment using different alcohols but keep mass/volume of water, height of container above wick, length of wick/ height of flame and number of moles of alcohol the same
30
what means a better fuel
less alcohol burned
an alcohol will be more efficient as a fuel compared to another alcohol if less fuel is needed to raise the temperature of the water by a given amount
longer the carbon chain the more efficient the fuel will be
31
what are nanoparticles
- tiny
- x 10 to the -9
- 1nm - 100nm is one nanoparticle
- contain a few hundred atoms so are bigger than atoms and simple molecules but smaller than everything else
- they have a high surface area to volume ratio allowing them to interact with anything they come into contact with
- as particles decrease in size the size of their surface area in relation to their volume increases
32
what are the uses of nanoparticles
- huge surface area to volume ratio so they make good catalysts because the bigger the surface for reactions to take place, the more collisions there will be and so the faster the rate of reaction
- sunscreens because they absorb radiation and don't leave marks on the skin
- nanomedicine is the idea that tiny fullerenes are absorbed more easily by the body than most particles so could deliver drugs right to the cells where they are needed
- lubricant coatings using fullerenes
- nanotubes conduct electricity so can be used in tiny electric circuits for computer chips
- nanoparticles added to sports equipment so make plastic stronger and more durable without adding much mass
- silver nanoparticles are added to the polymer fibres used to make surgical masks and wound dressings giving the fibres antibacterial properties
33
what are the effects of nanoparticles on health
- we don't know the effects on human health
- some nanoparticles used in medicine don't break down easily so they could start to build up in cells
- could cause lung inflammation if breathed in
34
what are the physical properties of some types of polymers
high density polyethene
- strong and rigid
low density polyethene
- light and stretchy
polystyrene
- foam used in packaging for protection and as a thermal insulator
heat resistant polymers like melamine resin and polypropene are used to make plastic kettles
35
what are cermaics
stiff but brittle
| made by baking substances like clay
36
discuss clay
- mineral formed by weathered and decomposed rock
- its soft when its dug up out of the ground which makes it easy to mould into different shapes required for pottery or bricks
- can be hardened by firing at very high temperatures
- this makes it ideal as building material as clay bricks can withstand the weight of lots more bricks on top of them
37
discuss glass
- generally transparent and strong
- can be moulded when hot and can be brittle when thin
- majority of glass is soda lime glass which is made by heating limestone, sand and sodium carbonate until they melt. When the mixture cools it comes out as glass
38
what are composites
- fibreglass and concrete
- made of one material (the reinforcement) embedded in another (the matrix/binder)
- the properties of a composite depend on the properties of the materials it is made from
39
what are some examples of composites
carbon fibre composites have been made using carbon atoms bonded together to make carbon fibres or carbon nanotubes held together in a polymer resin matrix. These polymers are expensive to make but are very strong and light making them ideal for use in aerospace and sports car manufacturing
- fibreglass
- concrete
- carbon fibre
40
what are metals good conductors of
- of heat and electrcity
- high density and mallebale
- mix to from alloys
41
discuss polymers
- flexible so can be bent without breaking and easily moulded into almost any shape
- often cheaper than most other materials
- less dense than most metals or ceramics so often used when designing products that need to be a low mass
- thermal and electrical insulators
- polymers can degrade over time so don't always last as long as things made from other materials
42
discuss ceramics
- insulators of heat and electricity
- more brittle and stiff than most other materials
- strong and hard wearing
- don't degrade or corrode so last a lot longer therefore we still use glass in windows instead of clear plastic
43
discuss metals
- good conductors of heat and electricity
- malleable
- some metals corrode easily but products made from corrosion resistant metals can last for a very long time
- usually less brittle than ceramics and polymers
- likely to deform but stay in one piece whereas other materials shatter
44
discuss composites
- different properties depending on matrix/binder and reinforcement
- combination of component materials used can be altered to have specific properties for specific purpose
- more expensive than other materials
