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AQA Chemistry > Organic Chemistry > Flashcards

Organic Chemistry Flashcards

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
types of alcohol
methanol CH3OH ethanol C2H5OH propanol C3H7OH butanol C4H9OH
26
how does alcohol react in air
- undergo complete combustion
27
how does alcohol react when added to water?
- soluble in water - give a solution with a neutral pH
28
how does alcohol react with sodium?
- produce hydrogen and a salt eg. sodium + methanol → sodium methoxide + hydrogen
29
how does alcohol react with an oxidising agent?
form carboxylic acids
30
uses of alcohols
- 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
how can ethanol be made naturally?
fermentation
32
how does fermentation happen?
- 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
(anaerobic) fermentation reaction
C6H12O6 + Enzymes → 2CO2 + 2C2H5OH
34
features of carboxylic acids
- functional group -COOH - homologous series - general formula CnH2n+1COOH
35
types of carboxylic acids
methanoic acid - HCOOH ethanoic acid - CH3COOH propanoic acid - C2H5COOH butanoic acid - C3H7COOH
36
how do carboxylic acids react with carbonates?
like any other acid but the salts formed in -anoate eg. ethanoic acid+sodium carbonate --> sodium ethanoate+water+carbon dioxide
37
how do carboxylic acids react with alcohols?
- form esters which have the functional group -COO- - acid catalyst usually used eg. concentrated sulfuric acid
38
ester formula
alcohol+carboxylic acid -acid catalyst-> ester+water eg. ethanoic acid+ethanol --> ethyl ethanoate+water
39
how do carboxylic acids dissolve in water?
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
why are carboxylic acids weak?
they dont fully ionise/dissociate into their H+ ions
41
what is addition polymerisation?
many small molecules (monomers) join together to form very large molecules (polymers)
42
features of addition polymers
- In addition polymers the repeating unit has the same atoms as the monomer because no other molecule is formed in the reaction
43
what are alkenes used to make?
polymers such as poly(ethene) and poly(propene) by addition polymerisation
44
what is condensation polymerisation?
- 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
addition vs condensation polymerisation
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
features of amino acids
- 2 functional groups NH2 + COOH eg. glycine (smallest amino acid)
47
how do amino acids react?
by condensation polymerisation to produce polypeptides
48
how do different amino acids react?
they combine is the same chain to form proteins (long chain/s of polypeptides)
49
what is DNA?
- 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
structure of DNA
two polymer chains, made from four different monomers called nucleotides, in the form of a double helix
51
other naturally occuring polymers
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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