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AS Chemistry - Unit 2 > Unit 3.2.10 - Alcohols > Flashcards

Unit 3.2.10 - Alcohols Flashcards

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1
Q

What functional group do alcohols have?

A

-OH

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2
Q

What is the general formula for an alcohol?

A

CnH(2n+1)OH

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3
Q

How do you name an alcohol?

A

Add the suffix -ol at the end instead of the -e, along with the number of the carbon atom it comes off

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4
Q

Draw propan-1,2-doil?

A

See flash card 5

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5
Q

If you have two or three OH groups on an alcohol which suffix would you use?

A
  • diol

- triol

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6
Q

Which two organic compounds share the functional group =O?

A

Aldehydes and ketones

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7
Q

What is the functional group of an aldehyde?

A

=O

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8
Q

What is the functional group of a ketone?

A

=O

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9
Q

What is the general formula for an aldehyde or ketone?

A

CnH2nO

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10
Q

What is the difference between an aldehyde and ketone in terms of structure?

A

In an aldehyde the =O functional group comes at the end of the chain where as in ketones the =O functional group comes within the chain

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11
Q

How do you name an aldehyde?

A

Add the suffix -al

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12
Q

How do you name ketones?

A

Add the suffix -one, along with the number of the carbon atom it comes of

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13
Q

Where in the chain does the functional group =O come for an aldehyde?

A

At the beginning or end

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14
Q

Where in the chain does the functional group =O come for a ketone?

A

Within the chain

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15
Q

Draw propanal?

A

See flash card 6

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16
Q

Draw propanone?

A

See flash card 7

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17
Q

What functional group do carboxylic acids have?

A

-COOH

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18
Q

What is the general formula for a carboxylic acid?

A

CnH(2n+1)COOH

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19
Q

How do you name carboxylic acids?

A

Add the suffix -oic acid

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20
Q

Draw propanoic acid?

A

See flash card 8

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21
Q

What two processes can you use to make ethanol?

A

Fermentation of sugars and hydration of ethane with steam

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22
Q

Describe what happens when ethanol is made by fermenting sugars?

A

Glucose is fermented by yeast and turned into ethanol and carbon dioxide

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23
Q

What is the optimum temperature for when you are fermenting glucose into ethanol and why?

A

30-40, too hot and enzymes would become denatured and too cold the reaction would happen too slowly

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24
Q

Why is the ethanol distilled off by fractional distillation when it is made by fermenting glucose?

A

When the concentration of ethanol get to 15% the yeast dies, so by tapping it off it stops this happening

25
Q

What is the equation for producing ethanol by fermentation?

A

C6H12O6 ———-> 2C2H5OH + 2CO2

26
Q

State the advantages and disadvantages of producing ethanol by hydrating ethene?

A

Advantages: Very fast, very pure, low labour costs
Disadvantages: the ethene comes from oil (finite resource), expensive equipment

27
Q

State the advantages and disadvantages of producing ethanol by fermenting glucose?

A

Advantages: glucose is extracted from plants and so is a renewable resource, cheaper equipment
Disadvantages: very slow, impure so needs purifying, high labour costs

28
Q

What is the difference in the type of process between producing ethanol by hydrating ethene and producing ethanol by fermenting sugars?

A

Hydrating ethene - continuous

Fermenting sugars - batch

29
Q

What is a biofuel?

A

A fuel that is made from biological material that has recently died

30
Q

Why ethanol produced by fermenting sugar carbon neutral?

A

The CO2 released when the fuel is burnt was removed by the crop as it grew

31
Q

What does carbon neutral mean?

A

An activity that has no net annual carbon emissions to the atmosphere

32
Q

What three groups can you divide alcohols up into?

A

Primary, secondary and tertiary

33
Q

What is a primary alcohol?

A

An alcohol where the carbon atom that the -OH is attached to is attached to 1 other carbon atom

34
Q

What is a secondary alcohol?

A

An alcohol where the carbon atom that the -OH is attached to is attached to 2 other carbon atoms

35
Q

What is a tertiary alcohol?

A

An alcohol where the carbon atom that the -OH is attached to is attached to 3 other carbon atoms

36
Q

Which alcohols cant be oxidised and why?

A

Tertiary because they don’t have any H atoms to give up

37
Q

Name an oxidising agent used when oxidising alcohols?

A

Potassium dichromate

38
Q

What can you represent an oxidising agent with?

A

[O]

39
Q

What is a primary alcohol first oxidised into?

A

An aldehyde

40
Q

Once a primary alcohol has been oxidised into an aldehyde what can it be further oxidised too?

A

A carboxylic acid

41
Q

What can a secondary alcohol be oxidised into?

A

A ketone

42
Q

What conditions do you use to try and get an aldehyde when oxidising a primary alcohol?

A

Warm it with the potassium dichromate and sulphuric acid doing a distillation reaction so that the aldehyde can be distilled off to stop it further reacting

43
Q

If you want to oxidise a primary alcohol to a carboxylic acid what do you do?

A

Heat it under reflux with potassium dichromate and sulphuric acid and oxidise it vigorously

44
Q

Why would you heat things under reflux when oxidising alcohols?

A

So that you don’t lose any reactants or products, it means any vaporised compounds cool and return back to the reaction mixture

45
Q

If you want to oxidise a secondary alcohol into a ketone what do you do?

A

Heat it under reflux with sulphuric acid and potassium dichromate

46
Q

What two test can you do to distinguish between aldehydes and ketones?

A

Tollen’s reagent and Fehling’s solution

47
Q

If you mixed Tollen’s reagent with an aldehyde and ketone and warmed it what results would you expect?

A

Aldehyde - silver mirror

Ketone - no visible change

48
Q

If you mixed Fehling’s solution with an aldehyde and ketone and warmed it what results would you expect?

A

Aldehyde - brick red precipitate

Ketone - solution stays blue

49
Q

What test can you do to distinguish between primary, secondary and tertiary?

A

When you heat them with potassium dichromate under distillation:
Primary and secondary the mixture will turn green
Tertiary the solution will remain orange

50
Q

What colour is potassium dichromate?

A

Orange

51
Q

What test can you do to distinguish between primary and secondary alcohols?

A

After oxidising them with potassium dichromate you can add either warm them with Tollen’s reagent or Fehling’s solution. If it was a primary alcohol there will be an aldehyde present so you will get a positive result for both tests. If it was a secondary alcohol there will be a ketone present so you won’t see any change from either of the tests.

52
Q

What type of reaction can alcohols go under to give alkenes?

A

Elimination

53
Q

Why is important that ethanol can under elimination to make ethene?

A

It means they can be made from renewable resources and be used to make polymers. This is because glucose is fermented to make ethanol, and then ethanol can undergo elimination to make ethene

54
Q

What conditions are used to make ethene from ethanol?

A

You heat ethanol under reflux with concentrated sulphuric aicd

55
Q

What are the two equations for making ethene from ethanol?

A

C2H5OH + H2SO4 ———-> C2H5OSO2OH + H2O

C2H5OSO2OH ———-> CH2=CH2 + H2SO4

56
Q

Draw the equation (using displayed formula) for when ethanol is oxidised into a aldehyde?

A

See flash card 9

57
Q

Draw the equation (using displayed formula) for when ethanol is oxidised into carboxylic acid?

A

See flash card 10

58
Q

Draw the equation (using displayed formula) for when propan-2-ol is oxidised into a ketone?

A

See flash card 11

59
Q

What does hydration mean in terms of hydrating ethanol?

A

Addition of steam

AS Chemistry - Unit 2 (11 decks)

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