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Chemistry A level > Alcohols > Flashcards

Alcohols Flashcards

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1
Q

How to specifically name an alcohol?

A

The ending of the name will be “ol”

For positioning put the C number where it occurs in-between the longest C chain ie Butan and the ol ending

If there’s more than one alcohol put di or tri in front of ol

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2
Q

As you increase the C chain in alcohols what happens to the boiling points?

A

The boiling points increase

Due to the molecules becoming bigger, so have more electrons

Fluctuations in their electron clouds become more likely and the strength of London forces increase.

More energy is required to separate the molecules

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3
Q

Why do alcohols have a higher boiling points than alkanes?

A

Alcohols can hydrogen bond, with other alcohol molecules

Hydrogen bonding is stronger than London forces

So more energy required to break them

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4
Q

What’s the maximum amount of water molecules a molecule of ethanol can bond to?

A

3, 2 hydrogens with the oxygen, and 1 oxygen with the hydrogen

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5
Q

Why does water solubility of the alcohols decrease as the chain length increases?

A

The OH group is the only part that interacts with the water.

As the chain length increases the effect of the OH group decreases, and that of the non polar (water insoluble) carbon chain becomes more important

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6
Q

Solvent a large alcohol would be able to dissolve in?

A

Any non polar solvent eg hexane

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7
Q

What does the combustion of an alcohol produce?

A

CO2 and H2O

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8
Q

Advantages of using ethanol as a fuel?

A

Much cleaner, undergoes more complete combustion

Has reduced amounts of greenhouse gases produced

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9
Q

Conditions required for dehydration of alcohols?

A

Heat under reflux

Catalyst of conc sulfuric acid or conc phosphoric acid

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10
Q

What does elimination mean?

A

Removal of atoms or groups from neighbouring C atoms to form an alkene, releasing a small molecule

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11
Q

How do you recognise an elimination reaction?

A

Goes from 1 molecule to 2 molecules

Increase in number of double bonds

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12
Q

Why can the elimination of alcohols also been known as a dehydration reaction?

A

Because the small molecule that is released is water

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13
Q

Example of a dehydration reaction?

A

CH3CH2OH = H2O + CH2=CH2

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14
Q

What are the 2 chemicals required to make an oxidising agent for alcohols?

A

Sodium dichromate solution or potassium dichromate solution

And dilute sulphuric acid

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15
Q

What’s the observation if a successful oxidising agent is created?

A

Reaction turns from orange to green

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16
Q

What determines what happens when an alcohol is oxidised?

A

The conditions employed

And whether the alcohol is primary, secondary or tertiary

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17
Q

What does reflux mean?

A

The continuous boiling and condensing of a reaction mixture, to prevent the loss of volatile components

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18
Q

What are the 3 possible products of oxidising an alcohol?

A

Aldehydye, ketone or carboxylic acid

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19
Q

What’s a primary alcohol?

A

When you remove the OH group, if the carbon it was bonded to is only bonded to one other Carbon

20
Q

What conditions are required to create an aldehyde from a primary alcohol?

A

Add oxidising agent, and gentle heating with distillation

21
Q

What process is used to separate out the aldehyde from the reaction mixture?

A

Distillation

22
Q

When an aldehyde is formed, what do you put at the very end of the name?

A

“al”

23
Q

Equation for ethanol oxidising to ethanol?

A

CH3CHOH + [O] = H2O + CH3CHO

24
Q

Aldehyde structure?

A

Carbon double bonded to an oxygen and single bonded to a hydrogen it’s the bonded to a carbon chain

25
Q

How do you prepare a carboxylic acid from a primary alcohol?

A

excess oxidising agent, and heat under reflux

26
Q

What do put at the end of the name when it’s at carboxylic acid?

A

“oic acid”

27
Q

Structure of a carboxylic acid?

A

Carbon double bonded to an oxygen, then single bonded to an OH group, then bonded to a Carbon chain

28
Q

Ethanol to ethanoic acid?

A

CH3CH2OH + 2[O]= CH3COOH + H2O

29
Q

Why is there a 2 in front of the oxidising agent when creating a carboxylic acid from a primary alcohol?

A

Had to oxidise it twice, from alcohol to aldehyde, then aldehyde to carboxylic acid

30
Q

Conditions required to oxidise secondary alcohols?

A

Heat under reflux, add excess oxidising agent

31
Q

What type of functional group is produced when a secondary alcohol is oxidised?

A

A ketone

32
Q

What do you put at the end of the name if an ketone is produced?

A

“one”

33
Q

Structure of a ketone?

A

Which ever Carbon the OH group was bonded to loses the OH group and it’s H, and stays bonded to each C chain next to it

34
Q

Propan-2-ol to propanone?

A

CH3CH(OH)CH3 + [O} = CH3COCH3 + H2O

35
Q

Can tertiary alcohols be oxidised?

A

No

36
Q

What’s the observation if attempting to oxidise tertiary alcohol?

A

Solution stays orange

37
Q

So colour changes for oxidising primary, secondary and tertiary alcohols?

A

Primary and secondary= Orange to Green

Tertiary = stays orange

38
Q

What’s the reaction with alcohols and hydrogen halides called?

A

Nucleophillic substitution

39
Q

What’s nucleophilic substitution?

A

Nucleophile is an atom or group of atoms which is attracted to an electron deficient carbon atom, where it can donate an electron pair forming a new covalent bond

Substitution is where one atom or group of atoms is replaced by a different atom or group of atoms

40
Q

Conditions for nucleophilic substitution of alcohols?

A

Heat under reflux

Create hydrogen bromide, by reacting NaBr + H2SO4

41
Q

Nucleophillic substitution equation for Ethanol + sulphuric acid + sodium bromide?

A

C2H5OH + NaBr + H2SO4 = C2H5Br + H2O + NaHSO4

42
Q

What’s the process of esterification?

A

Carboxylic acid + alcohol = Ester + water

43
Q

What conditions are required for esterification?

A

Conc sulphuric acid catalyst

Heat under reflux

44
Q

How do you name an ester?

A

first word ends in “yl”
second word ends in “oate”

Longest alcohol chain determines what goes in front of “yl”, and longest C chain in carboxylic acid determines what goes in front of “oate”

Eg. Methanol + Ethanoic acid = methyl ethanoate + water

45
Q

How to determine the name of an ester by looking at it’s structure?

A

Find the C double bonded to an oxygen, and also single bonded to another oxygen

Find the longest C chain next to the single bonded oxygen to determine what’s in front of the “yl” and therefore what the alcohol is

Then to find the carboxylic acid count the longest C chain the other direction, including the C double bonded to the Oxygen, to find out what’s in front of the “oate” and therefore the carboxylic acid

Chemistry A level (16 decks)

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