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Edexcel Chemsitry > Topic 9: Separate Chemistry 2 > Flashcards

Topic 9: Separate Chemistry 2 Flashcards

1
Q

describe how to carry out the flame test for identifying metal ions

A
  • first clean a nichrome wire loop by dipping it into hydrochloric acid and then rinsing it in distilled water
  • then dip the wire loop into a sample of the metal compound and put the loop in the clear blue part of a bunsen flame
  • record what colour the flame goes
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2
Q

what colour change does the flame undergo when burning lithium

A

lithium ions give crimson red flame

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3
Q

what colour change does the flame undergo when burning sodium

A

sodium ions give yellow flame

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4
Q

what colour change does the flame undergo when burning potassium

A

potassium ions give lilac flame

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5
Q

what colour change does the flame undergo when burning calcium

A

calcium ions give orange-red flame

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6
Q

what colour change does the flame undergo when burning copper

A

copper ions give a blue-green flame

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7
Q

describe the precipiate test for metal ions (using NaOH)

A
  • add a few drops of sodium hydroxide solution to a solution of your mystery compound
  • if a hydroxde precipitate forms, you can use it’s colour to tell which metal ion was in the compound
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8
Q

when testing metal ions with precipitate rection using NaOH, what is the colour of precipiate and provide an ionic equation for aluminium ions

A

colour of precipitate = white at first, then redissolves in excess NaOH to form colourless solution

ionic equation (see pic)

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9
Q

when testing metal ions with precipitate rection using NaOH, what is the colour of precipiate and provide an ionic equation for calcium ions

A

colour of precipitate = white

ionic equation (see pic)

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10
Q

when testing metal ions with precipitate rection using NaOH, what is the colour of precipiate and provide an ionic equation for copper ions

A

colour of precipitate = blue

ionic equation (see pic)

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11
Q

when testing metal ions with precipitate rection using NaOH, what is the colour of precipiate and provide an ionic equation for iron 2+ ions

A

colour of precipitate = green

ionic equation (see pic)

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12
Q

when testing metal ions with precipitate rection using NaOH, what is the colour of precipiate and provide an ionic equation for iron 3+ ions

A

colour of precipitate = brown

ionic equation (see pic)

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13
Q

describe the protocol for testing if a substance contains ammonium ions (NH4 ^+)

A
  • add some sodium hydroxide solution to a solution of mystery substance and gently heat it.
  • if ammonia gas is given off, there are ammonium ions present in mystery solution
  • to test for ammonia gas, hold a piece of damp red litmus paper over it. If ammonia is present then litmus papeer will turn blue
  • ammonia gas also has a srong smell but dont sniff the gas to figure out what it is as at high concentrations, ammonia is an irritant and can be toxic
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14
Q

describe the protocol for testing halide ions (chloride, bromide, iodide) using silver nitrate solution using ionic equations

A
  • to test for hallide ions, add some dilute nitric acid (HNO₃), followed by a few drops of silver nitrate solution (AgNO3)
  • a chloride gives a white precipiate of silver chloride
    Ag+ (aq) + Cl- (aq) -> AgCl (s)
  • a bromide gives a cream precipiate of silver bromide
    Ag+(aq) + Br- (aq) -> AgBr (s)
  • an iodide gives a yellow precipitate of silver iodide
    Ag+ (aq) + I- (aq) -> AgI (s)
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15
Q

when testing halide ions (chloride, bromide, iodide) using silver nitrate solution why is nitric acid added first

A

to get rid of any carbonate ions as they produce a pale precipitate with silver nitrate too , which would confuse results

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16
Q

when testing for hallide ions (chloride, bromide, iodide) using silver nitrate solution, why can’t you use hydrochloric acid

A

you would be adding chloride ions to the solution which would react

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17
Q

describe the test for carbonate ions (CO₃²⁻) using dilute acid, using an ionic equation

A
  • to test for carbonate ions (CO₃²⁻), in solution, add some dilute acid
  • if there are carbonate ions present, effervescence occurs as the carbonate will react with the acid to produce carbon dioxide gas

ionic equation (see pic)

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18
Q

how can you test for carbon dioxide gas

A

bubble gas through timewater and if carbon dioxide is present then limewater turns milky

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19
Q

describe the test for sulfate ions using barium chloride solution and include an ionic equation

A
  • to test for sulfate ions in solution, first add some dilute hydrochloric acid to the test sample - this stops any precipitation reactions not involving sulfate ions from taking place
  • then add some barium chloride solution. if there are sulfate ions present, a white precipitate of barium sulfate will form
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20
Q

what is flame photometry

A

an intrumental method that allows you to identify ions in a dilute solution

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21
Q

methof for finding concentration from a flame photometry experiment

A
  • find the intensity on the why axis
  • travl along horizontally from this point, unitl you reach the curve
  • draw a straight line down to the x-axis and read of concentration
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22
Q

how does flame photometry work for mixtures

A
  • a solution containing different ions might give a certain spectrum
  • you can then compare this spectrum against reference spectra
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23
Q

what is the benefit of using flame photometry instead of flame tests

A

flame tests only work for substances that contain a single metal ion whereas flame ohotometry can be used to identify metal ions in mixtures

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24
Q

what are the advantages of using machines for intrumental analysis

A
  • very sensitive: they can detect even the tiniest amounts of substances
  • very fast: and tests can be automated
  • very accurate: thye don’t involve human error, like manual analysis does
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25
Q

define homolgous series

A

a group of chemicals that have simialr chemical structures and differ by CH2 and have the same functional group

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26
Q

what are alkanes

A

a homologous series of hydrocarbons

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27
Q

define a hydrocarbon

A

they contain hydrogen and carbon atoms only

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28
Q

what is the general formula for alkanes

A
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29
Q

displayed formula for methane

A
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30
Q

displayed formula for ethane

A
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31
Q

displayed fomrula for propane

A
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32
Q

displayed formula for butane

A
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33
Q

what word is used to describe alkanes and why

A

saturated molecules because all the bonds are formed from the carbon molecules

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34
Q

describe alkenes

A

a homologous serioes of hydrocarbons with one C=C functional group

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35
Q

general formula for alkenes

A
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36
Q

what word can describe alkenes and why

A

unsaturated as the double bond between carbon atoms can be broken and more bonds can form

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37
Q

displayed formula for ethene

A
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38
Q

displayed formula for propene

A
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39
Q

displayed formula for but-1-ene

A
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40
Q

displayed formula for but-2-ene

A
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41
Q

explain how can you test for an alkene using bromine water

A
  • when an alkene and bromine water is shaken together, the alkene will decolourise the bromine water, turning it from orange to colourless.
  • this is because an addition reaction takes place where bromine is added across the alkene double bond
42
Q

what can alkenes also react with in an addition reaction

A

steam

43
Q

show equation for adding bromine water to an alkene

A

you need to be able to demonstrate this with multiple alkenes, wherever the double bonds are, bromine atoms bind

44
Q

show how the complete combustion of an alkane produces carbon dioxide and water

A
45
Q

show how the complete combustion of an alkene produces carbon dioxide and water

A
46
Q

what is a polymer

A

a substance of high average relative
molecular mass made up of small repeating units

47
Q

Describe how ethene molecules can combine together in a
polymerisation reaction to produce poly(ethene)

A

Ethene molecules combine together in a polymerisation reaction and the addition polymer formed is called poly(ethene).

48
Q

how to name a polymer

A

put brackets around the type of monomer it’s made from and put ‘poly’ in front of it

49
Q

how to find the formula of a polymer

A

put formula of the monomer in brackets and put a little ‘n’ after it

50
Q

how to draw the repeat unit of a polymer

A

join carbons together in a row with no double bonds between then, stick a pair of brackets around the repeating bit, and oout and ‘n’ after it to show theres lots of monomers
- also draw a bond from each of the 2 carbons in the chain that pass through the brackets to show the chain continues

51
Q

how to get the diplayed formula of a polymer to the displayed formula of the monomer

A

draw the repeating unit of the polymer, get rid of the 2 bonds going out through the brackets and put a double bond between the carbons

52
Q

what are the properties and uses of poly(ethene)

A

properties: flexible, electrical insulator, cheap

uses: plastic bags, bottles, wire insulation

53
Q

what are the properties and uses of poly(propene)

A

properties: flexibel, strong, tough, mouldable

uses: crates, furniture, ropes

54
Q

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

A

properties: touch, cheap

uses: window frames, water pipes

55
Q

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

A

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

56
Q

explain why are polyesters condensation polymers

A

As each time an ester link is formed, a water molecule is lost.

57
Q

explain how a polyester is formed when a monomer molecule containing two carboxylic acid groups is reacted with a monomer molecule containing two alcohol groups

A

When a (dicarboxylic acid) monomer with two carboxylic acid groups combines with a (diol) monomer with two alcohol groups, a polyester is formed.

58
Q

explain how a molecule of water is formed each time an ester link is formed.

A

A molecule of water is former when a -OO functional group from the carboxylic acid monomer combines with a H molecule lost from the alcohol monomer.

59
Q

describe condensation polymerisation

A
  • involves 2 different types of monomers
  • the monomers react together and bond form between them, making polymer chains
  • each monomer has to contain at least 2 functional groups, one on each of the molecule
  • each functional group can react with the functional group of another monomer, crating long chains of alternating monomers. for each new bond that from, a small molecule (usually water) is lost
60
Q

how are polyesters formed

A

dicarboxylic acid monomers and diol monomers react together

61
Q

describe how polyesters are formed

A
  • the dicarboxylic acid monomers contain 2 carboxylic acid (-COOH) groups and the diol monomers contail 2 alcohol (-OH) groups
  • when the carboxylic acid group reacts with the alcohol group, it forms an ester link
  • each time an ester link is formed, a molecule of water is lost
62
Q

describe DNA as a naturally occuring polynmer

A
  • DNA is a complex molecule that contains genetic information
  • it contains 2 strands and each stand is made up of nucleotide monomers that bond together in a polymerisation reaction
  • DNA is made from four different monomers called nucleotide
63
Q

describe amino acids as naturally occuring polymers

A
  • amino acid monomers for polymers known as protein via condesation polymerisation
  • proteins have many important uses in the human body e.g. enzymes
64
Q

describe how carbohydrates are naturally occuring polymers

A
  • 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
65
Q

describe disposal of polymers in landfill sites

A
  • a lot of plastics get dumped in landfill sites. This is usually when different polymers are too difficult or expensive to separate and recycle
  • lot’s of valuble land is quickly getting used up for use as landfill sites
  • most polymers are non-biodegradable - they’re not broken down by micororganisms. This means that they will sit in landfill for years and years…
66
Q

describe disposal of polymers by combustion

A
  • burning plastic producs a lot of energy and this cab 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 - this has to be removed
  • carbon dioxide is also produced and this contributes to global warming
67
Q

advantages of recycling polymers

A
  • reduces amount of non-biodegradable waste filling up landfill sites
  • reduces emissions of greenhouse and toxic gases which can be released from burning polymers
  • recycling generally uses less water and energy resources than when making new plastics
  • redcues the amount of crude oil need to produce more plastics
  • recycling generally saves money and creates jobs
68
Q

disadvantages of recycling polymers

A
  • polymers must be separated by type before they can be melted and reformed into a new product - this 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 plants and animals
69
Q

what is the functional group of alcohol

A

-OH group

alcohols end in -ol

70
Q

general formula for alcohols

A
71
Q

Recall the formulae of molecules of the alcohols, methanol, ethanol, propanol (propan-1-ol only) and butanol (butan-1-ol
only), and draw the structures of these molecules, showing all
covalent bonds

A
72
Q

what happens to alcohols to make them carboxylic acids

A

they are oxidised

73
Q

naming system for carboxylic acids

A

ends in ‘-oic acid’

74
Q

general formula for carboxylic acid

A
75
Q

functional group for carboxylic acids

A

-COOH

76
Q

why do members of a given homologous series have similar reactions

A

their molecules contain the same functional group

77
Q

Recall the formulae of molecules of the carboxylic acids, methanoic, ethanoic, propanoic and butanoic acids, and draw the structures of these molecules, showing all covalent bonds

A
78
Q

describe how ethanol can be produced by fermentation

A

-suagr can come from any source
- yeast cells contain an enzyme
- mix yeast and a solution of a carbohydrate ina. clean container. Seal the container and leave in a warm place.
- keep the mixture between 30 and 40 degrees celcius - fermentation happens fastest between these temps. At lower temps the reaction slows down. If its too hot the enzyme in yeast will denature and the reaction would stop
- its important to keep mixture in anaerobic conditions. Oxygen converts the ethanol to ethanoil acid
- when the concentration of alcohol reaches about 10-20% the fermentation reaction stops, because the yeast gets killed off by the alcohol
- the yeast will fall to the bottom of the container - you can collect ethanol solution from the top
- the fermented mixture can be distilled to produce more concentrated alcohol

79
Q

what is fermentation

A

the process of using yeast to convert sugars into alcohol

80
Q

Explain how to obtain a concentrated solution of ethanol by fractional distillation of the fermentation mixture

A

1) A dilute solution of ethanol is produced by fermentation.
2) To make a concentration of ethanol above 20%, ethanol must be concentrated by fractional distillation of the fermentation mixture.
Fractional distillation separates mixtures by heating them.
3) Ethanol has a lower boiling point than water. This means that when
the fermentation mixture is heated, ethanol evaporates and the vapour rises up the fractionating column, while the water stays as a liquid.
4) A Liebig condenser is used to condense the ethanol vapour by cooling it. The concentrated ethanol can then be collected in a separate flask.

81
Q

why can alcohols be used as fuels

A

when they are burned they release energy

82
Q

describe practical for burning alcohol to heat up water

A

1) Put some alcoholinto a spirt burner and measure the mas of the burner and fuel using a mes balece
Alcohols are hazardous to humans — e.g. methanol is toxic and propanol is an irritant - so you should make sure you’re wearing gloves and safety glasses.
2) Meesure 100 cm distiled water into a coppper calorimeter (use the sare container for each experiment)
3) Insulate the calorimeter by using a draught excluder, then cover with an insulating lid after placing a thermometer inside. This helps to make sure that minimal energy is lost to the surroundings.
4) Take the initial temperature of the water then put the burner under the calorimeter and light the wick. Alcohol is highly flammable so direct contact with the flame should be avoided - just light the wick.
5) Stir the water throughout using the thermometer. When the heat from the burner has made the temperature of the water rise by 20 °C, blow out the spirit burner. The apparatus will get hot during the experiment, so you should allow it to cool before touching it, or use tongs.
6. immediately reweigh the burner and fuel
7) repeat the experiment using other alcohols but make sure that you keep all other variables the same for each exoeriment, including mass/ volume of water, height of container abover the wick, length or wick/ height of flame, number of moles of alcohol

83
Q

how can you use results from experiment of alcohol heating up water to compare the efficiency of alcohols as fuels

A
  • less alcohol burned means a better fuel
84
Q

Compare the size of nanoparticles with the sizes of atoms and molecules

A

● Nanoparticles are 1-100 nanometers across. ● They contain a few hundred atoms.
● Nanoparticles, are smaller than fine particles, which have diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m).

85
Q

Describe how the properties of nanoparticulate materials are related to their uses

A
  • They have a huge surface area to volume ratio, so they can make good catalysts. This is because reactions take place on the surface of catalysts, so the bigger the surface area, the more collisions there will be and so the faster the rate of reaction.
  • New cosmetics, e.g. sunscreens, have been made using nanoparticles.
    The small particles provide better protection but don’t leave white marks on the skin.
  • Nanomedicine is a hot topic. The idea is that tiny fullerenes are absorbed more easily by the body than most particles. This means they could deliver drugs right into the cells where they’re needed.
  • New lubricant coatings using fullerenes could be used in, e.g. artificial joints and gears.
  • Nanotubes conduct electricity, so they can be used in tiny electric circuits for computer chips.
  • Nanoparticles are added to plastics in sports equipment, e.g. tennis rackets, golf clubs and golf balls. They make the plastic much stronger and more durable, without adding much mass (hardly any at all).
  • Silver nanoparticles are added to the polymer fibres used to make surgical masks and wound dressings. This gives the fibres antibacterial properties
86
Q

Explain the possible risks associated with some
nanoparticulate materials

A
  • don’t know what the side effects or long-term impacts on health could be.
  • some nanoparticles used in medicine dont break down easilt so they could start to build up in cells which could also cause problems such as lung inflammation if they are breathed in
87
Q

what are strong rigid polymers used for

A

to make water pipes

88
Q

what are light stretchy polymers used for

A

plastic bags and squeezy bottle

89
Q

what is polystrene foam used for

A

package to protect breakable things and as a thermal insulator

90
Q

what are heat resistant polymers used for

A

make plastic kettles

91
Q

what properties do ceramic have

A

brittle and stiff

92
Q

describe clay as a ceramic material

A
  • a mineral found from weathered and decomposed rock. It’s soft when it’s dug up out of the ground, which makes it easy to mould into different shapes required for pottery or bricks
  • it can be hardened bu firing at very high temps. this makes it ideal as a building meaterial - clay bricks can withstand the weight of lots more bricks on top of them
93
Q

describe glass a ceramic

A
  • glass in generally transparent and strong, can be moulded when hot and can be brittle when thin
  • the majority of glass made is soda-lime glass which is made by heating limestone, sand and sodium carbonate until they melt. When this mixture xools it comes out as glass
94
Q

describe metals as a material

A

Metals are malleable and ductile, so they can be bent into shape or made into wires without shattering. Unlike glass and clay ceramics, metals are good electrical
conductors.

95
Q

compare melting point, appearence, malleability, and conductivity of glass clay and metals

A
96
Q

describe polmers as a material

A

Polymers are poor conductors of electricity and heat, but their other properties vary depending upon the particular polymer. For example, they can be transparent or opaque. They are often tough and flexible, but some are hard and brittle.

97
Q

how are polymers suited to their jobs

A

Polymers are really adaptable - e.g. they are often flexible so can be bent without breaking and can be easily moulded into almost any shape.
- they are often cheaper than most other materials and tend to be less sense than most metals or ceramic so often used when deigning products that need to have a low mass.
- they are also thermal and electrical insulators.
- polymers can degrade and break down over time, so polymer products dont always last as long as those made from other materials

98
Q

describe how ceramic are suited to their job

A
  • insulators of heat and electricity
  • more brittle and stiff than most other materials but are also strong and hard wearing
  • they dont degrade or corrode like other materials can so last longer - why glass windows are used and not plastic
99
Q

describe how metals are suited to their job

A
  • good conductors of heat and electricity
  • are malleable so can be formed into a variety of shapes
  • some materials corrode easily but products made from corrosion resistant materials can last for a very long time
  • metals are usually less brittle than either ceramic or polymers so they are likely to deform but stay in one piece where other materials may shatter
100
Q

describe how compostis are suited for their different jobs

A
  • have different properties depending on the mature/ binder and the reinforcement.
  • the combination of component materials used can be altered so composites can be designed to have specific properties for a specific purpose
  • the main disadvantage of composites is that they tend to be much mroe expensive to produce than other materials

Edexcel Chemsitry (9 decks)

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