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Koky chem > SC22 & SC23 & SC24 - Hydrocarbons / Alcohols and Carboxylic Acids / Polymers > Flashcards

SC22 & SC23 & SC24 - Hydrocarbons / Alcohols and Carboxylic Acids / Polymers Flashcards

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1
Q

SC22a - What is a hydrocarbon?

A

A molecular compound containing only hydrogen and carbon atoms

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2
Q

SC22a - What is the functional group of an alkane?

A

Trick question. They have no functional group

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3
Q

SC22a - What is the general formula of an alkane?

A

CnH2n+2

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4
Q

SC22a - What are the first four prefixes for all the homologus serieses?

A
  1. Meth- (Don’t do drugs)
  2. Eth-
  3. Prop-
  4. But-
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5
Q

SC22a - According to the IUPAC, how are hydrocarbons (and many other molecule types) named?

A
  • Prefix showing its number (e.g. Meth- is 1)
  • Suffix showing its homologous series (e.g -ane is alkane)
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6
Q

SC22a - Why is an alkane saturated?

A

It only contains single bonds between carbon atoms meaning it can’t open out and bond to more atoms

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7
Q

SC22a - What are the displayed and molecular formulae of the first four alkanes?

A
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8
Q

SC22a - What is a functional group?

A

The part of a molecule that identifieis it with its specific functional group and is responsible for its chemical properties

(e.g all carboxylic acids have COOH )

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9
Q

SC22a - What is the functional group of an alkene?

A

All alkenes contain one double covalent bond between two carbon atoms

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10
Q

SC22a - What is the general formula of an alkene?

A

CnH2n

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11
Q

SC22a - Why is there no ‘methene’ ?

A

A meth- alkene would have 1 carbon atom but to be an alkene, it would need a double bond between carbons, which can’t happen, unless there are 2+ carbon atoms

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12
Q

SC22a - Why is an alkene unsaturated?

A

It contains a double covalent bond between two carbon atoms, meaning that the bond can be opened out and another atom can bond to it.

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13
Q

SC22a - What are the molecular and displayed formula of the first 3 alkenes (remember there isn’t a ‘methene’)

A
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14
Q

SC22a - What is an isomer?

A

The same molecule with their functional group placed in different places.

e.g. below is but-1-ene (as the group is in it’s first possible position) and but-2-ene (with the group in the second position)

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15
Q

SC22a - Why are there no isomers of ethene and propene?

A
  • Ethene only has 2 carbon atoms and so the double bond can only be in one place
  • Propene has 3 carbon atoms and so the double bonds can be in 2 places however, positioning them in these two places would make reflections of the same molecule
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16
Q

SC22b - How do alkanes and alkenes react in combustion?

A
  • When heated up sufficiently, hydrocarbons will oxidise, and combust, reacting with the oxygen in the air and releasing energy
  • When sufficient oxygen is present, all the hydrocarbon will oxidise (complete combustion)
    • Hydrocarbon + Oxygen → Carbon dioxide + water
  • When there is a lack of oxygen, not all of the hydrocarbon will oxidise (incomplete combustion) Carbon monoxide and/or carbon aswell, instead of just carbon dioxide
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17
Q

SC22b - How can you tell if a chemical is an alkene or an alkane?

A
  • When placed in and mixed with bromine water, an alkane won’t react and no change will be observed
  • However, the double bond in an alkene, will open out and react with the bromine water taking it out of the water and it goes from orange-brown to colourless
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18
Q

SC22b - What colour is bromine water?

A

Orange-brown

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19
Q

SC22b - What is an addition reaction

A

When more than one reactant reacts to form a larger product and no other products

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20
Q

SC22b - What is the word equation for the addition reaction between ethene and bromine water?

A

Ethene + Bromine water → 1,2 dibromoethane

(Don’t know if this is required knowledge)

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21
Q

SC23a - What are the uses of ethanol?

A
  • Alcoholic beverages
  • Fuel for vehicles
  • Material in raw industry
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22
Q

SC23a - What is ethanol made from?

A
  • Sugars. These are small soluble substances that belong to a group called carbohydrates
  • Seeds contain a carb called starch (a long polymer).
  • Germinating seeds allows enzymes to break down the starch into sugars
  • Fermentation uses enzymes in yeast to turn the sugars into ethanol
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23
Q

SC23a - What plants are used to make different alcoholic beverages?

A
  • Beer - Barley seeds
  • Wine - Grapes
  • Whisky - Barley seeds
  • Vodka - Wheat seeds
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24
Q

SC23a - Describe the fermentation process of ethanol

A
  • In fermentation we start with a sugar solution such as glucose and we mix it with yeast (natural catalyst) , the yeast (provides the enzymes needed for fermentation) then converts the sugar solution to a solution of ethanol. Carbon dioxide is also produced.
  • The temperature should be 35-40 degrees Celsius
  • The reaction must take place in anaerobic conditions (without oxygen)
  • Glucose → ethanol + carbon dioxide
  • If air is present, the oxygen causes the ethanol to oxidise to ethanoic acid
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25
Q

SC23a - What is the problem with the fermentation process and how is this overcome?

A

Only alcohol of 15% concentration can be produced (or else the yeast enzymes will be killed). So, fractional distillation is used to obtain high concentrations of alcohol.

Ethanol’s b.p. of 78 C is less than water and so it evapourates first and condenses into a distillate of high conc. ethanol

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26
Q

SC23b - What is an organic compound?

A

A compound with a central framework of carbon atoms but with hydrogen and other atoms attached

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27
Q

SC23b - What is the functional group of the alcohols homologous series?

A

-OH atoms on the end of the compound

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28
Q

SC23b - What is the general formula of alcohols?

A

CnH2n+1

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29
Q

SC22a - What are the first four alkanes?

A
  • Methane
  • Ethane
  • Propane
  • Butane
  • -ane is prefix
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30
Q

SC22a - What are the first three alkenes?

A
  • Ethene
  • Propene
  • Butene
  • -ene is prefix
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31
Q

SC23b - What are the first four alcohols?

A
  • Methanol
  • Ethanol
  • Propanol
  • Butanol
  • -anol is prefix
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32
Q

SC23c - What are the first four carboxylic acids?

A
  • Methanoic acid
  • Ethanoic acid
  • Propanoic acid
  • Butanoic acid
  • -anoic acid is prefix
33
Q

SC23b - What is the displayed and molecular formula of the first four alcohols

A
34
Q

SC23b - What are the chemical properties of the alcohols?

A
  • Produce carbon dioxide + water during complete combustion
  • Can be oxidised to produce carboxylic acids
  • React with reactive metals and produces hydrogen (among other products)
35
Q

SC23b - What is the trend of reactivity for alcohols?

A

The longer the chain, the less vigorously they will react (for example less bubble produced when sodium is added)

36
Q

SC23b - What are some uses of alcohols?

A
  • Medical products
  • Fuels
  • Varnishes
  • Cosmetics
37
Q

SC23b - Describe the trend in energy stored per Litre for alcohols

A

Longer chains store more energy per litre, making them more effective fuels

38
Q

SC23b - What is so advantageous about alcohol fuel?

A

They can be made from renewable sources such as fermenting plant cellulose using bacteria. (Currently methanol and ethanol fuels are being used)

39
Q

SC23c - Why does wine turn into vinegar when left out?

A

The ethanol oxidises and turns into ethanoic acid (a type of vinegar)

40
Q

SC23c - Describe the process of the oxidisation of an alcohol

A
  • The Oxygen molecule from the air collides with the functional group of the alcohol
  • Two hydrogen molecules are ‘knocked off’ and bond with an oxygen to form water
  • Meanwhile the other oxygen bonds to the carbon forming a carboxylic acid
41
Q

SC23c - What is the functional group of a carboxylic acid?

A

-COOH at the end

42
Q

SC23c - What is the displayed and molecular formula of the first four carboxylic acids?

A
43
Q

SC23c - What is the general formula of carboxylic acids?

A

CnH2n+1COOH

[Ok real talk guys. The above general formula is the one you need to know. However, unlike in other general formulas, the ‘n’ value isn’t the number in the series (idk what it is). So if you want a general formula based off number in series, Cn-1H2n-1COOH but if they ever ask in the exam what the general formula, it is the top one as that is the spec one]

44
Q

SC23c - What are oxidising agents and why are they used?

A
  • The natural process of oxidisation of an alcohol is time consuming and uncontrollable.
  • Instead, reacting an alcohol with an compound that contains oxygen is more effective.

e.g Propanol + (hot) copper oxide → Propanoic acid + Water + Copper

45
Q

SC23c - What are the chemical properties of carboxylic acids?

A
  • Form solutions with pH <7 (if soluble)
  • React with metals to from salt and hydrogen
  • React with bases to form salt and water
  • React with carbonates to form salt water and carbon dioxide
46
Q

SC23c - What gives carboxylic acids their acidity?

A

The -COOH group has a H+ ion which makes it acidic

47
Q

SC23c - How can vinegar be used to test for chalk/limestone?

A

Chalk/limestone are carbonates and so when vinegar is added, the ethanoic acid will fizz due the presence of carbon dioxide produced from the reaction

48
Q

SC23c - Describe the trend in acidity of carboxylic acids

A

The longer the chain the less acidic (higher pH)

49
Q

SC24a - What are plastics made from?

A

Polymers

50
Q

SC24a - What is a polymer?

A

A long molecule made up of lots of tiny molecules called monomers

51
Q

SC24a - What is polymerisation?

A

The process by which many monomers are joined together to form a polymer

52
Q

SC24a - What is special about the relative atomic mass of polymers?

A

They can be very large due to having millions of molecules. As they can be any lengths, they are never given

53
Q

SC24a - What is addition polymerisation?

A

When many of the same monomer are added together to form one polymer and no other products

54
Q

SC24a - Describe the addition polymerisation of ethene into poly(ethene)

A
55
Q

SC24a - What is the repeating unit of a polymerisation equation?

A

It shows how the monomer has changed and how it repeats throughout the polymer chain

56
Q

SC24a - What is a synthetic polymer?

A

One manufactured in a lab/factory

57
Q

SC24a - What are some examples of naturally occurring polymers?

A
  • Starch (made of glucose)
  • Protein (made of amino acids)
  • DNA (made from nucelotides)
58
Q

SC24b - How are polymers named?

A

Poly(name of monomer)

59
Q

SC24b - Why can alkenes be used to make polymers?

A

They contain a double carbon bond that can be opened out to bond to more monomers

60
Q

SC24b - What is key to remember when drawing repeating units?

A

Make sure the bond lines go through the brackets to show that it can continue to bond

61
Q

SC24b - Properties and uses of Poly(ethene)

A
  • Common name: Polythene
  • Properties: Flexible, cheap
  • Uses: Plastic bags, cling film
62
Q

SC24b - Properties and uses of Poly(propene)

A
  • Common name: polypropylene (wtf is the common name longer)
  • Properties: Flexible, shatter resistant
  • Uses: Buckets and bowls, ropes
63
Q

SC24b - Properties and uses of Poly(chloroethene)

A
  • Common names: polyvinyl chloride PVC
  • Properties: Tough, good insulator
  • Uses: Pipes, window frames
64
Q

SC24b - Properties and uses of Poly(tetrafluorene)

A
  • Common names: PTFE, Teflontm
  • Properties: Tough, slippery
  • Uses: Burette taps, non-stick coating
65
Q

SC24c - What is a polyester?

A

A synthetic polymer made by condensation polymerisation. It contains many ester links

66
Q

SC24c - What is the functional group of an ester?

A
67
Q

SC24c - How are esters formed?

A
  • When a carboxylic acid is reacted with an alcohol

Carboxylic acid + alcohol → ester + water

68
Q

SC24c - Why is an ester-creating reaction considered a condensation reaction?

A

Water is produced

69
Q

SC24c - How would ethanoic acid and ethanol react to form an ester?

A

The -OH from the ethanoic acid and the H from the ethanol will break off and react to form water. Then, the C on the acid will bond with the O from the alcohol

70
Q

SC24c - What is required to form a polyester?

A

Each monomer has a functional group on BOTH sides

e.g. below is ethanoic acid and ethanol

71
Q

SC24c - What will a polymer equation for the condensation polymerisation of ethanoic acid and ethanol?

A

This process is something that should be practiced as you need to practice drawing it out

72
Q

SC24d - What is the problem with the process to make synthetic polymers?

A

They are obtained from crude oil which is a non-renewable finite resource and will eventually run out

73
Q

SC24d - What does biodegradable mean?

A

It can rot as mircrobes can break it down

74
Q

SC24d - What are the pros and cons of synthetic polymers being non-biodegradable?

A

+ They can be used for a long time

  • They don’t rot when thrown away
75
Q

SC24d - What are the pros and cons of incinerating plastic rubbish?

A

+ Takes up less space

+ Energy released can be used to generate electricity

  • Produces Carbon dioxide (GH gas)
  • Some plastics produce toxic substances when burnt (these can be removed but forms toxic ash which needs to be disposed)
76
Q

SC24d - How can we reduce the amount of waste going to incinerators and landfill sites?

A

Re-using and recycling materials

77
Q

SC24d - Describe the process of recycling polymers

A
  • Collection (kerbside or recycle points)
  • Sorting (can be expensive and time consuming)
  • Disposal of un-recyclable wast to landfill sites
  • Clean polymers and grind to chippings
  • Purify chippings
  • Melt and remould chippings
78
Q

SC24d - How is the sorting process of recycling made easier?

A

Labels for each type of polymer

Koky chem (24 decks)

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