Topic 9- separate chemistry 2 Flashcards
what colour flame does lithium give
crimson (red)
what colour flame does sodium give
yellow
what colour flame does potassium give
lilac
what colour flame does calcium give
orange-red
what colour flame does copper give
blue-green
how do you carry the flame test out
-clean a nichrome wire loop by dipping it in hydrochloric acid and then rinsing in distilled water
-then dip wire loop in sample of the metal compound and put loop in clear blue part of flame of bunsen flame
-record the colour
how do you carry out the test that uses hydroxide precipitates to tell which metal ion was in a compound
add a few drops of sodium hydroxide to the mystery compound, if hydroxide precipitate forms look at the colour
what colour precipitate does aluminium Al3+ give
white at first and then redissolves in excess NaOH to form colourless solution
what colour precipitate does calcium Ca2+ give
white
what colour precipitate does Copper Cu2+ give
Blue
what colour precipitate does Iron(ll) Fe2+ give
green
what colour precipitate does Iron(lll) Fe3+ give
Brown
how do work out if a substance contains ammonium ions
add sodium hydroxide solution and gently heat, if ammonia gas is given off it contains ammonium ions
how do you test for ammonia gas
hold a piece of damp red litmus paper over it, it gas is ammonia it will turn blue
how do you test for halide ions
add some dilute nitric acid (to get rid of carbonate atoms) followed by a few drops of silver nitrate solution
what colour precipiatate does chloride give
white, silver chloride
what colour precipitate does bromide give
cream, silver bromide
what colour precipitate does iodide give
yellow, silver iodide
how to test for carbonate atoms
add some dilute acid, if mixture fizzes there are carbonate atoms present because the carbonate will react to the acid to produce CO2
how to test for CO2
bubble gas through limewater, if it goes milky carbon dioxide is present
how to test for sulfate ions
-add dilute HCl, stops any precipitation reactions not involving sulfate ions from taking place
- add barium chloride solution, if there are sulfate ions in the solution a white precipitate of barium sulfate will form
what are the advantages of using machines to analyse unknown substances
- very sensitive- can detect even the tiniest amounts of substances
-very fast and test can be automated
-very accurate- they dont invlove human error, like manual analysis does
what general formula do alkanes have
CnH2n+2
are alkanes saturated or unsaturated
saturated, all the atoms have formed bonds with as many other atoms as they can
what is the general formula of alkenes
CnH2n
are alkenes unsaturated or saturated
unsaturated, because they can make more bonds, the double bonds can open up, allowing two the two carbon atoms to bond with other atoms
how can you test for alkenes
use bromine water, when shaken together, an alkene will decolourise bromine water, turning it from orange to colourless because an addition reaction takes place where bromine is added across the alkene double bond
what happens to hydrocarbons in combustion reactions
they’re oxidised to form carbon dioxide and water
how are polymers made
by joining up lots of small repeating units called monomers
what is addition polymerisation
when alkenes open up their double bonds and join together to form polymer chains
how do you draw the displayed formula of an addition polymer from the displayed formula of its monomer
join carbons in a row with no double bonds, stick a pair of brackets around the repeating bit and put an ‘n’ after it, also put a bond from each of the two carbons in the chain to show the chain continues
what are the properties and uses of Poly(ethene)
uses: plastic bags, bottles, wire insulator
properties: flexible, electrical insulator, cheap
what are the properties and uses of Poly(propene)
uses: crates, furniture, ropes
properties: flexible, strong, tough, mouldable
what are the properties and uses of Poly(chloroethene) (PVC)
uses: window frames, water pipes
properties: tough, cheap
what are the properties and uses of poly(tetrafluoroethene) (PTFE)
uses: non-stick pans, waterproof clothing
properties: unreactive, tough, non-stick
what is condensation polymerisation
when two different types of monomers react together and bonds form between them, making polymer chains
what re the negatives of disposing of polymers by landfill
valuable land is used up and polymers are non-biodegradable so wont be broken down by microorganisms
what are the negatives of disposing of polymers by combustion
toxic gases are produced as well as CO2 which is bad for the environment
advantages of recycling polymers
reduces waste and emissions of bad gases, uses up less water and energy resources than making new polymers, saves money, makes jobs, less crude oil is used up
disadvantages of polymers
must be separated which is expensive and annoying, if the polymers are mixed the quality is worse, polymers can only be recycled a finite number of times, melting of polymers releases toxic gases
what is the formula of alcohols
CnH2n+1OH
what are the first four alcohols in the homologous series
methanol, ethanol, propanol, butanol
what is a dehydration reaction
when a mixture oof alcohol and an acid catalyst are heated, and an alkene and water are formed
i dont have the strength left in me to do the rest of this
sorry :(
