Topic 9- separate chemistry 2

Question 1

what colour flame does lithium give

Answer 1

crimson (red)

Question 2

what colour flame does sodium give

Answer 2

yellow

Question 3

what colour flame does potassium give

Answer 3

lilac

Question 4

what colour flame does calcium give

Answer 4

orange-red

Question 5

what colour flame does copper give

Answer 5

blue-green

Question 6

how do you carry the flame test out

Answer 6

-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

Question 7

how do you carry out the test that uses hydroxide precipitates to tell which metal ion was in a compound

Answer 7

add a few drops of sodium hydroxide to the mystery compound, if hydroxide precipitate forms look at the colour

Question 8

what colour precipitate does aluminium Al3+ give

Answer 8

white at first and then redissolves in excess NaOH to form colourless solution

Question 9

what colour precipitate does calcium Ca2+ give

Answer 9

white

Question 10

what colour precipitate does Copper Cu2+ give

Answer 10

Blue

Question 11

what colour precipitate does Iron(ll) Fe2+ give

Answer 11

green

Question 12

what colour precipitate does Iron(lll) Fe3+ give

Answer 12

Brown

Question 13

how do work out if a substance contains ammonium ions

Answer 13

add sodium hydroxide solution and gently heat, if ammonia gas is given off it contains ammonium ions

Question 14

how do you test for ammonia gas

Answer 14

hold a piece of damp red litmus paper over it, it gas is ammonia it will turn blue

Question 15

how do you test for halide ions

Answer 15

add some dilute nitric acid (to get rid of carbonate atoms) followed by a few drops of silver nitrate solution

Question 16

what colour precipiatate does chloride give

Answer 16

white, silver chloride

Question 17

what colour precipitate does bromide give

Answer 17

cream, silver bromide

Question 18

what colour precipitate does iodide give

Answer 18

yellow, silver iodide

Question 19

how to test for carbonate atoms

Answer 19

add some dilute acid, if mixture fizzes there are carbonate atoms present because the carbonate will react to the acid to produce CO2

Question 20

how to test for CO2

Answer 20

bubble gas through limewater, if it goes milky carbon dioxide is present

Question 21

how to test for sulfate ions

Answer 21

-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

Question 22

what are the advantages of using machines to analyse unknown substances

Answer 22

• 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

Question 23

what general formula do alkanes have

Answer 23

CnH2n+2

Question 24

are alkanes saturated or unsaturated

Answer 24

saturated, all the atoms have formed bonds with as many other atoms as they can

Question 25

what is the general formula of alkenes

Answer 25

CnH2n

Question 26

are alkenes unsaturated or saturated

Answer 26

unsaturated, because they can make more bonds, the double bonds can open up, allowing two the two carbon atoms to bond with other atoms

Question 27

how can you test for alkenes

Answer 27

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

Question 28

what happens to hydrocarbons in combustion reactions

Answer 28

they're oxidised to form carbon dioxide and water

Question 29

how are polymers made

Answer 29

by joining up lots of small repeating units called monomers

Question 30

what is addition polymerisation

Answer 30

when alkenes open up their double bonds and join together to form polymer chains

Question 31

how do you draw the displayed formula of an addition polymer from the displayed formula of its monomer

Answer 31

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

Question 32

what are the properties and uses of Poly(ethene)

Answer 32

uses: plastic bags, bottles, wire insulator properties: flexible, electrical insulator, cheap

Question 33

what are the properties and uses of Poly(propene)

Answer 33

uses: crates, furniture, ropes properties: flexible, strong, tough, mouldable

Question 34

what are the properties and uses of Poly(chloroethene) (PVC)

Answer 34

uses: window frames, water pipes properties: tough, cheap

Question 35

what are the properties and uses of poly(tetrafluoroethene) (PTFE)

Answer 35

uses: non-stick pans, waterproof clothing properties: unreactive, tough, non-stick

Question 36

what is condensation polymerisation

Answer 36

when two different types of monomers react together and bonds form between them, making polymer chains

Question 37

what re the negatives of disposing of polymers by landfill

Answer 37

valuable land is used up and polymers are non-biodegradable so wont be broken down by microorganisms

Question 38

what are the negatives of disposing of polymers by combustion

Answer 38

toxic gases are produced as well as CO2 which is bad for the environment

Question 39

advantages of recycling polymers

Answer 39

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

Question 40

disadvantages of polymers

Answer 40

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

Question 41

what is the formula of alcohols

Answer 41

CnH2n+1OH

Question 42

what are the first four alcohols in the homologous series

Answer 42

methanol, ethanol, propanol, butanol

Question 43

what is a dehydration reaction

Answer 43

when a mixture oof alcohol and an acid catalyst are heated, and an alkene and water are formed

Question 44

i dont have the strength left in me to do the rest of this

Answer 44

sorry :(