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AQA Chemistry > Organic Chemistry > Flashcards

Organic Chemistry Flashcards

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1
Q

what is crude oil?

A
  • remains of plankton that was buried in mud and compressed over time
  • a mixture of a very large number of compounds which are mainly hydrocarbons
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2
Q

what is a hydrocarbon?

A

molecules made up of hydrogen and carbon atoms only

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3
Q

what are alkanes?

A
  • simplest form of hydrocarbons
  • homologous series (all react similarly)
  • all end in -ane
  • CnH2n+2 (general formula)
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4
Q

types of alkanes

A

methane - CH4
ethane - C2H6
propane - C3H8
butane - C4H10

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5
Q

how is crude oil separated?

A

fractional distillation

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6
Q

how are hydrocarbons in crude oil used?

A
  • processed to produce fuels and feedstock for the petrochemical industry
  • fuels eg. petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases (dependent on these due to our modern lifestyle)
  • useful materials are produced
    by the petrochemical industry eg. solvents, lubricants,
    polymers, detergents (dependent on these due to our modern lifestyle)
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7
Q

how do the different fractions of crude oil happen?

A

due to the ability of carbon atoms to form families of similar
compounds=wide variety of natural and synthetic carbon compounds

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8
Q

properties of hydrocarbons

A

shorter hydrocarbons:
- less viscous
- low b.p=more volatile
- more flammable
these all affect how they’re used as fuels, short chain hydrocarbons with low b.p are used as bottled gases (LPGs)
- saturated due to C-C single bond

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9
Q

complete combustion of hydrocarbons

A

hydrocarbon+oxygen –> carbon dioxide+water (+energy)
- both the caron and hydrogen are oxidised

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10
Q

what is cracking?

A

breaking down long chain hydrocarbons into smaller hydrocarbons which are more useful as fuels

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11
Q

types of cracking

A

catalytic - using a catalyst
steam - using steam

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12
Q

how does cracking work?

A

in a cracker, heavier fractions are heated to high temp to vaporize hydrocarbons
- vapour can be either passed over a hot catalyst or mixed with steam and heated to extremely high temp

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13
Q

products of cracking

A

shorter alkane
alkene

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14
Q

why is cracking useful?

A

allows us to meet the high demand of fuels with shorter hydrocarbons

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15
Q

properties of alkenes

A
  • more reactive then alkanes due to being unsaturated (C=C double bond)
  • used to make polymers and as starting materials to make other products
  • react with bromine water (test of hydrocarbons)
  • homologous series
  • CnH2n (general formula)
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16
Q

bromine water test

A

orange bromine water turns colourless when an alkene is added, forming a dibromo-compound

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17
Q

types of alkenes

A

ethene - C2H4
propene - C3H6
butene - C4H8
pentene - C5H10

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18
Q

(incomplete) combustion of alkenes

A

alkene+oxygen –> carbon+carbon monoxide+carbon dioxide+water (+energy)

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19
Q

how do alkenes react?

A

via addition reactions
most of them react similarly due to having the same functional group C=C

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20
Q

how do alkenes react with water/steam?

A
  • when alkenes react steam, water is added across double bond=alcohol formed
    eg. ethene+steam then passing over a catalyst=ethanol
  • done industrially
  • after the reaction occurs, reaction mixture is passed from reactor to a condenser because ethanol and water both have higher b.p than ethene so they both condense and any unreacted ethene is recycled back to the reactor
  • alcohol is then purified through fractional distillation
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21
Q

how do alkenes react with hydrogen?

A
  • called hydrogenation
  • hydrogen opens up double bonded carbons to form a saturated alkane
  • reacts in the presence of a catalyst
22
Q

how do alkenes react with halogens?

A
  • C=C double bond opens up and forms a saturated molecule as each carbon from the double bond bonds with a halogen atom
23
Q

how do alkenes react with oxygen?

A

in combustion reactions but they tend to burn in air with smoky flames because of incomplete combustion

24
Q

features of alcohols

A
  • functional group -OH
  • general formula CnH2n+1OH
  • homologous series
25
Q

types of alcohol

A

methanol CH3OH
ethanol C2H5OH
propanol C3H7OH
butanol C4H9OH

26
Q

how does alcohol react in air

A
  • undergo complete combustion
27
Q

how does alcohol react when added to water?

A
  • soluble in water
  • give a solution with a neutral pH
28
Q

how does alcohol react with sodium?

A
  • produce hydrogen and a salt
    eg. sodium + methanol → sodium methoxide + hydrogen
29
Q

how does alcohol react with an oxidising agent?

A

form carboxylic acids

30
Q

uses of alcohols

A
  • methanol and ethanol are used as solvents in the industry because they can dissolve anything water dissolves and other substances water can’t dissolve eg. hydrocarbons, oils and fats
  • fuels eg ethanol is used as a fuel in spirit burners - burn fairly cleanly and non-smelly
  • ethanol is used in alcoholic drinks eg. wine+beer
31
Q

how can ethanol be made naturally?

A

fermentation

32
Q

how does fermentation happen?

A
  • sugar or starch is dissolved in water and yeast is added
  • the mixture is then fermented between 15 and 35°C with the absence of oxygen for a few days
  • works fastest at 37 C, in a slightly acidic solution, with no oxygen
  • yeast contains enzymes that break down sugar to glucose
  • yeast are killed off once the concentration of alcohol reaches around 15%, hence the reaction vessel is emptied and the process is started again
  • reason why ethanol production by fermentation is a batch process
33
Q

(anaerobic) fermentation reaction

A

C6H12O6 + Enzymes → 2CO2 + 2C2H5OH

34
Q

features of carboxylic acids

A
  • functional group -COOH
  • homologous series
  • general formula CnH2n+1COOH
35
Q

types of carboxylic acids

A

methanoic acid - HCOOH
ethanoic acid - CH3COOH
propanoic acid - C2H5COOH
butanoic acid - C3H7COOH

36
Q

how do carboxylic acids react with carbonates?

A

like any other acid but the salts formed in -anoate
eg. ethanoic acid+sodium carbonate –> sodium ethanoate+water+carbon dioxide

37
Q

how do carboxylic acids react with alcohols?

A
  • form esters which have the functional group -COO-
  • acid catalyst usually used eg. concentrated sulfuric acid
38
Q

ester formula

A

alcohol+carboxylic acid -acid catalyst-> ester+water
eg. ethanoic acid+ethanol –> ethyl ethanoate+water

39
Q

how do carboxylic acids dissolve in water?

A

when they dissolve, they ionise and release H+ ions=acidic solution but they partially ionise=weak acidic solutions
- so they a higher pH then aqueous solutions of strong acids with the same concentration

40
Q

why are carboxylic acids weak?

A

they dont fully ionise/dissociate into their H+ ions

41
Q

what is addition polymerisation?

A

many small molecules
(monomers) join together to form very large molecules (polymers)

42
Q

features of addition polymers

A
  • In addition polymers the repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction
43
Q

what are alkenes used to make?

A

polymers such as poly(ethene) and poly(propene) by addition polymerisation

44
Q

what is condensation polymerisation?

A
  • involves monomers with two
    functional groups
  • when these types of monomers react they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions.
  • simplest polymers are made from two different monomers with two of the same functional groups
    eg. ethanediol and hexanedioic acid polymerise to make a polyester
45
Q

addition vs condensation polymerisation

A

addition
- only one monomer with a C=C double bond
- only one product formed
- only one functional group on a monomer (C=C)

condensation
- two monomers with the same functional group eg. ethanol and propanol
- two types of product formed, a polymer and a small molecule ge. water
- two functional group on a monomer

46
Q

features of amino acids

A
  • 2 functional groups NH2 + COOH eg. glycine (smallest amino acid)
47
Q

how do amino acids react?

A

by condensation polymerisation to produce polypeptides

48
Q

how do different amino acids react?

A

they combine is the same chain to form proteins (long chain/s of polypeptides)

49
Q

what is DNA?

A
  • large molecule essential for life
  • encodes genetic material
    Most DNA molecules are two polymer chains, made from four
    different monomers called nucleotides, in the form of a double helix.
    Other naturally occurring polymers important for life include
    proteins, starch and cellulose.
50
Q

structure of DNA

A

two polymer chains, made from four different monomers called nucleotides, in the form of a double helix

51
Q

other naturally occuring polymers

A

starch and cellulose which are made from sugars which are small molecules that contain carbon, oxygen and hydrogen
- sugars react together through polymerisation to form larger carbohydrate polymers

AQA Chemistry (10 decks)

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