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chemistry A1 organic > 3.3.5 Alcohols > Flashcards

3.3.5 Alcohols Flashcards

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1
Q

why do alcohols have high boiling points

A

they can form hydrogen bonds with other molecules

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2
Q

what are the key points when naming alchols

A

drop the e with the prefix

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3
Q

what are the different ways to classify alcohols

A

primary
secondary
tertiary

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4
Q

what are primary alcohols

A

1 carbon is joined to the oxygen

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5
Q

what are secondary alcohols

A

the carbon joined with the oxygen is bonded to two other carbons

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6
Q

what are teritary alcohols

A

the carbon bonded to oxygen is joined to bonded to 3 carbons

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7
Q

what is the bonding present in alcohols

A

hydrogen bonding
van Deer Waal
dipole-dipole forces

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8
Q

what type of molecules are alcohols

A

polar molecules

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9
Q

are short chained alcohols soluble in water

A

yes

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9
Q

why does the solubility decrease to the longer carbon chain

A

greater region of non-polar molecules
which is highly insoluble

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10
Q

what can primary alcohols be oxidised into

A

aldehydes

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11
Q

what can aldehydes be oxidised into

A

carboxylic acids

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12
Q

what can secondary alcohols be oxidised into

A

ketones

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13
Q

what can tertiary alcohols be oxidised into

A

it cant be oxidised

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14
Q

why can primary and secondary alcohols be oxidised

A

the carbon-hydrogen bond breaks

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15
Q

what reagent oxidises primary and secondary alcohols

A

acidified potassium dichromate

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16
Q

what is the molecular formula for postassium dichromate

A

K2Cr2O7

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17
Q

what is the positive result for the oxidation of alcohols

A

orange to green

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18
Q

what acid acidifes potassium dichromate

A

sulfuric acid

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19
Q

what do alcohols lose **

A

2 hydrogens

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20
Q

what is thee half equation for chromium

A

Cr2O7^2- + 6e- + 14H+ –> 2Cr^3+ +7H2O

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21
Q

how can the oxidising agent be rrepresented as

A

[O]

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22
Q

what causes the green colour change

A

the chromium ion
Cr 3+

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23
Q

where is the water in on the fractional distillation column

A

the water in is always at the bottom

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24
Q

what are the conditions of the oxidation of primary alcohols

A

acidifed potassium dichromate
under reflux

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25
Q

what is reflux

A

where the vapour condenses back into the liquid

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26
Q

what is the function of the condenser?

A

prevents organic vapour from escaping by condensing them back to liquids

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27
Q

why should you never seal the condenser

A

there will be a build up of pressure
and it will explode

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28
Q

what is a description of the condenser

A

the long thing with the water in and water out bit

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29
Q

why is water in at the bottom

A

to prevent the backflow of water

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30
Q

why are electric heaters used

A

organic chemicals are highly flammable

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31
Q

what is thee purpose of anti-bumping granules

A

to prevent vigorous, uneven boiling
by making small bubbles form instead of largee bubbles

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32
Q

how do anti-bumping granules work

A

they form small bubbles instead of large bubbles

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33
Q

what are the reagents for the oxidation of alcohols

A

acidified potassium dichromate

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34
Q

what are the conditions for the oxidation of secondary alcohols

A

heat under reflux

35
Q

why cant tertiary alcohols be oxidised

A

there is no hydrogen atom bonded to the carbon with the -OH group

36
Q

what is produced under reflux

A

carboxylic acid and ketone

37
Q

how can we extract ketones

A

using distillation

38
Q

how can we produce aldehydes

A

distillation

39
Q

what things shouldn’t you include in a fractional column

A
  • no gap between condenser and flask
  • dont draw lines between flask and condenser
    -dont forget the water in and water out section
40
Q

what reagent is used to test for aldehydes andd ketones

A

Tollens’ Reagent

41
Q

what is the results for the Tollen’s Reagent test

A

aldehydes- silver mirror
ketones- no colour change

42
Q

what is the positive result for aldehydes with the Tollens Reagent

A

silver mirror percipitate

43
Q

what is the result for ketones when Tollens reagent is added

A

no colour change

44
Q

what are the conditions for the Tollen’s Reagent test

A

heated gently

45
Q

what is another reagent used for the testing of aldehydes and ketones

A

Fehlings Solution

46
Q

what are the results when aldehydes and ketones are tested by Fehling’s solution

A

aldehydes: blue to brick red percipitate
ketones: blu, no colour change

47
Q

what is the positive results for the test using Fehling’s solution

A

aldehydes: blue to brick red

48
Q

how can we test for carboxylic acids

A

sodium hydrogencarbonate

49
Q

what is observed when we test for carboxylic acids

A

fizzing and effervescent
CO2 is produced

50
Q

what is meant by a dehydration reaction

A

when a water molecule is removed

51
Q

what is the type of reaction is a dehydration reaction

A

elimination reaction

52
Q

what reagent is used in the elimination/dehydration reaction

A

concentrated acid catalyst

53
Q

what type of acid catalyst is usd in the elimination reaction

A

concentrated sulfuric acid

54
Q

how are alchols converted to alkenes

A

by an elimination reacttion

55
Q

what is the general formula of the elimination reaction

A

alcohol -> alkene + water
<-

56
Q

what type of reaction is an elimination reaction

A

reversible reaction

57
Q

what does producing alkenes from alcohols provide

A

a route to polymers

58
Q

what is the hydration of alkenes involve

A

an acid catalyst
and steam

59
Q

why is the hydration of alkenes considered as electrophilic addition

A

cause sulfuric acid can act as an electrophile

60
Q

what are the conditions for feermentation

A

yeast
no oxygen
temperarure: 25-40 degrees

61
Q

what should the temperature be for fermentation

A

between 25 and 40 degrees

62
Q

why shouldnt we use low temperatures for fermentation

A

the reaction would be too slow

63
Q

what is thee purpose of yeast in fermenation

A

it has an enzyme which catalyses the process

64
Q

what is the process of fermentation

A

add warm water to sugar
then add yeast
aking sure theres no O2

65
Q

why shouldnt we carry out fermentation at high temperatures

A

the enxymes denature

66
Q

why is fermentation done in the absence of air

A

air can oxidise ethanol into ethanoic acid (vinegar)

67
Q

what is the balanced equation for the formation of ethanol from fermentation

A

2glucose–> 2ethanol + 2carbon dioxde

68
Q

what are the disadvantages of fermentation of ethanol

A
  • batch process which is slower
  • ethanol is not pure and is purified by fractional distillation
  • depletes lands for crops
69
Q

how is ethanol separated from fermentation

A

fractional distillation

70
Q

what are the advantages of the fermentation of ethanol

A
  • sugar is a renewable source
  • cheaper
  • lower energy
71
Q

where does the reagent from the industrial formation of ethene come from

A

ethene comes from cracking of crude oil

72
Q

what is the reraction calledd for the industral formation of ethanol

A

hydration/elimination

73
Q

what are the conditions in the industrial formation of ethene

A
  • high temps 300 degrees
  • high pressure 6000kpa
  • acid catalst: H3PO4
74
Q

what is the temperature when ethanol is made industrially

A

300 degrees

75
Q

what is the pressure when ethanol is made industrially

A

6000 kPa

76
Q

what catalyst is used when ethanol is made industrially

A

concentrated phosphoric acid

77
Q

what are the advantages when ethanol is made industrially

A
  • faster reaction
  • high percentage atom economy
  • purer product
78
Q

with the hydration of alkenes what does the ouble bond attack

A

the delta positive H on the acid

79
Q

what are the disadvantages when ethanol is made industrially

A

ethene is non-renewable
high energy costs
expensive

80
Q

what attacks after the double bond attacks the hydrogen

A

the water

81
Q

what is biofuel

A

a fuel made from plants

82
Q

what is meant by the term carbon neutral

A

an activity that has no net carbon dioxide to the atmosphere

83
Q

why is the prodution of ethanol considered as carbon neural

A

cause of the removal of 6CO2 in photosynthesis
the production of 6CO2 from fermentation&combustion

6CO2 absorbed 6CO2 emitted

84
Q

however, why isnt the formation of ethanol fully carbon neutral

A

CO2 is produced in transportation
machinery and fertticlicers for plants

85
Q
A

chemistry A1 organic (5 decks)

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