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A-Level Chemistry > Alcohols > Flashcards

Alcohols Flashcards

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1
Q

What is the functional group in alcohols?

A

Hydroxyl group

-OH

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2
Q

What is the general formula for alcohols?

A

CnH2n+1OH

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3
Q

What are the different types of alcohols?

A

Primary
Secondary
Tertiary

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4
Q

What is a primary alcohol?

A

An alcohol where the carbon attached to the hydroxyl group is attached to 1 other alkyl group

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5
Q

What is a secondary alcohol?

A

An alcohol where the carbon attached to the hydroxyl group is attached to 2 other alkyl groups

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6
Q

What is a tertiary alcohol?

A

An alcohol where the carbon attached to the hydroxyl group is attached to 3 other alkyl groups

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7
Q

What are the properties of alcohols?

A

Low volatility

High boiling points

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8
Q

Why do alcohols have high boiling points?

A

They have hydrogen bonding

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9
Q

How can alkenes be made using alcohols?

A

Alkenes can be mad by eliminating water in alcohols in a dehydration reaction

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10
Q

What is the general formula for dehydration of alcohols?

A

CnH2n+1OH → CnH2n + H2O

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11
Q

What does this reaction allow to happen?

A

It allows for alkenes to be produced from renewable resources.
Therefore, polymers can be made without the need for oil.

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12
Q

What is one of the main industrial uses for alkenes?

A

It is used as a starting material for polymers

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13
Q

What is the equation for the dehydration of ethanol?

A

C2H5OH → C2H4 + H2O

concentrated sulfuric acid and phosphoric acid are used as catalyts for this reaction

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14
Q

How can alcohols be produced from alkenes?

A

Alcohos can be produced by the hydration of alkenes in the presence of an acid catalyst.

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15
Q

How can ethanol be produced?

A

Ethanol can be produced by the hydration of ethene

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16
Q

What is the equation for the hydration of ethene

A

C2H4 + H2O → C2H5OH

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17
Q

What are the conditions for the hydration of ethene?

A

concentrated phosphoric acid
300 degrees
60 atm

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18
Q

What are the advantages of producing ethanol by hydration of ethene?

A

Faster reaction
Continuous process
Lower labour costs
Ethanol produced is 99.9% pure

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19
Q

What are the disadvantages of producing ethanol by hydration of ethene?

A

Non-renewable source of ethene
Expensive initial costs
Higher temperatures and pressures

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20
Q

How can ethanol be produced?

A

Ethanol can be produced by fermentation of glucose

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21
Q

What is the equation for fermentation of glucose?

A

C6H12O6(aq) → 2C2H5OH(aq) + 2CO2(g)

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22
Q

What are the conditions for fermentation of glucose?

A 
zymase(yeast)
anaerobic
warm
aqueous
30-40 degrees
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23
Q

What are the advantages of fermentation to produce ethanol?

A

Sugar is renewable
Cheap
Lower temperatures and pressures

24
Q

What are the disadvantages of fermentation to produce ethanol?

A 
Slow
Batch process
Ethanol produced is impure
Purification by distillation needed
Higher labour costs
Land could be used to grow food crops
25
Q

Ethanol produced using the fermentation method is considered a biofuel.
What is a biofuel?

A

A biofuel is a fuel that’s made from a biological material that’s recently died

26
Q

Why can the fermentation method be considered carbon neutral?

A

The carbon dioxide produced is equal to the carbon dioxide absorbed during photosynthesis

27
Q

What are the equations that show that there is no net contribution to CO2?

A

Photosynthesis: 6CO2+ 6H20 → C6H12O6 + 6O2

Fermentation : C6H12O6 → 2C2H5OH + 2CO2
Combstion: 2C2H5OH + 6O2→ 4CO2 + 6H2O

28
Q

Why is ethanol production by fermentation of glucose, not carbon neutral?

A

The ethanol produced has to be fractionally distilled
Powering of machinery
Transportation of the ethanol

29
Q

What affects how much an alcohol can be oxidised?

A

The structure of the alcohol

30
Q

What is the oxidising agent used to oxidise alcohols?

A

Acidifed potassium dichromate(VI)

K2Cr2O7

31
Q

What can be observed when the acidified potassium dichromate oxidises the alcohols?

A

The orange dichromate(VI) ion(Cr2O7^2-) is reduced to the green chromium ion(Cr^3+)

32
Q

What are primary alcohols oxidised to?

A

Aldehydes and then carboxylic acids

33
Q

What are secondary alcohols oxidised to?

A

Ketones

34
Q

What are tertiary alcohols oxidised to?

A

They can’t be oxidised

35
Q

What is an aldehyde?

A

It is a carbonyl group with a hydrogen and one alkyl group attached to the carbonyl carbon atom

36
Q

What is a ketone?

A

It is a carbonyl group with two alkyl groups attached to the carbonyl carbon atom

37
Q

What is the functional group of aldehydes and ketones?

A

C=O

38
Q

What is the general formula of aldehydes and ketones?

A

CnH2nO

39
Q

What is the suffix for aldehydes?

A

-al

40
Q

What is the suffix for ketones?

A

-one

41
Q

What is the functional group of carboxylic acids?

A

COOH

42
Q

What is the general formula of carboxylic acids?

A

CnH2n+1COOH

43
Q

What is the suffix for carboxylic acids?

A

-oic acid

44
Q

What are the conditions for oxidising primary alcohols to aldehydes?

A

Excess alcohol
Warm gently
Distillation

45
Q

What is the general formula for the partial oxidation of primary alcohols?

A

Primary alcohol + [O] → Aldehyde + water

46
Q

What are the conditions for the oxidation of aldehydes to carboxylic acids?

A

Excess acidified potassium dichromate

Heat under reflux

47
Q

What is the general formula for the oxidation of aldehydes to carboxylic acids?

A

Aldehyde + [O] → Carboxylic acid

48
Q

What are the conditions for oxidising secondary alcohols into ketones?

A

Heat under reflux

Excess acidified potassium dichromate

49
Q

What is the general formula for the oxidation of secondary alcohols?

A

Secondary alcohol + [O] → Ketone + water

50
Q

How can we distinguish between ketones and aldehydes?

A

We can use:
Tollen’s reagent
Fehling’s/Benedicts’s solution

51
Q

What is Tollen’s reagent

A

Ammoniacal silver nitrate

52
Q

What is Fehling’s/Benedict’s solution?

A

Solutions of deep blue Cu2+ ions

53
Q

What would happen if we used Tollen’s reagent to distinguish between ketones and aldehydes?

A

Aldehydes would form a silver mirror (the silver ions have been reduced to silver atoms)

Ketones would show no visible change

54
Q

What would happen if we used Fehling’s/Benedict’s solution to distinguish between ketones and aldehydes?

A

Aldehydes would form a brick-red precipitate of Cu2O(copper ions have been reduced to copper(I) oxide

55
Q

What would be the equation for the reaction between ethanal and Tollen’s reagent?

A

CH3CHO + 2Ag+ + H2O → CH3COOH + 2Ag + 2H+

56
Q

What would be the equation for the reaction between ethanal and Fehling’s/Benedict’s solution?

A

CH3CHO + 2Cu^2+ + 2H2O → CH3COOH + Cu2O + 4H+

A-Level Chemistry (30 decks)

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