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Chemistry Cook Y12 > Alcohols Unit 4 > Flashcards

Alcohols Unit 4 Flashcards

1
Q

Define an alcohol

A

Compounds in which one or more hydrogen atoms in an alkene have been replaced by a hydroxyl Group

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2
Q

Why does the boiling point of alcohols increase with increasing chain length

A

The attractions get stronger as the molecules get longer and have more electrons- increase size of temporary dipoles

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3
Q

What is complete oxidation called

A

Combustion

C2H5OH + O2 –> CO2 + H2O

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4
Q

How to oxidise alcohols

A

Add acidified potassium dichromate

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5
Q

What colour changes happens when you oxidise Butan-1-ol

A

Orange to green

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6
Q

Balanced equation for the oxidation of Butan-1-ol to a carboxylic acid

A

C4H9OH + 2[O] —> C3H7COOH + H2O

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7
Q

What conditions are need for the dehydration of an alcohol?

A

An acid catalyst phosphoric or sulphuric acid

And heat

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8
Q

What does the dehydration of an alcohol form

A

An alkene and a molecule of water

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9
Q

Which alcohol reacts the fastest with concentrated hcl

A

Tertiary

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10
Q

What are primary alcohols oxidised to and what does it require?

A

Aldehydes

Distillation

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11
Q

What happens to an aldehyde if heated further with excess acidified potassium dichromate and under reflux?

A

Carboxylic acid

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12
Q

What are secondary alcohols oxidised to and what does it require?

A

Ketones

Reflux

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13
Q

Colour changed of the three types of alcohols

A

Primary- green
Secondary- green
Tertiary- orange (no change)

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14
Q

Why can’t tertiary alcohols be oxidised

A

They don’t have a hydrogen atom attached to that carbon

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15
Q

Physical properties of haloalkanes

A

Immiscible with water

Boiling point depends on size and number of halogens

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16
Q

Define a nucleophile

A

An electron pair donor

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17
Q

What is nucleophillic substitution and what does it require

A

Hydrolysis reaction that requires aqueous NaOH

Must be under reflux

18
Q

How does the nucleophillic substitution bond break

A

Heterolytic fission

19
Q

How is heterolytic fission facilitated

A

By a negatively charged substance reacting with the positively charged carbon atom in a haloalkane

20
Q

Why is dilute nitric acid added to haloalkane with ethanol

A

Prevents unreacted hydroxide ions reacting with the silver ions

21
Q

Colour of Cl- precipitate

A

White precipitate

22
Q

Colour of Br- precipitate

A

Very pale cream precipitate

23
Q

Colour of I- precipitate

A

Very pale yellow precipitate

24
Q

What happens to the precipitate when ammonia solution is added to AgCl

A

Precipitate dissolves to give a colourless solution

25
Q

What happens to the precipitate when ammonia solution is added to AgBr

A

Precipitate is almost unchanged using dilute ammonia solution, but dissolves in concentrated ammonia solution to give a colourless solution

26
Q

What happens to the precipitate when ammonia solution is added to AgI

A

Precipitate is insoluble in ammonia solution of any concentration

27
Q

Hydrolysis rates of primary, secondary and tertiary alcohols

A

Tertiary halide produces a precipitate almost instantly
The secondary halide gives a slight precipitate after a few seconds. The precipitate thickens up with time
The primary halide May take considerably longer to produce a precipitate

28
Q

Reagents and conditions needed to mix 2 alcohols

A

Acid catalyst
Steam
High temp

29
Q

Why are some solutions more soluble than others

A

Weak intermolecular forces
OH- Group is polar as is water
OH- group can hydrogen bond with water

30
Q

Who concluded that CFCs remain stable until they reach the stratosphere

A

Rowland and Molina

31
Q

How do CFCs deplete the ozone layer

A

UV radiation breaks C-Cl bonds by homolytic fission

32
Q

What is it called when radiation initiates the breakdown

A

Photodissociation

33
Q

What was the global agreement called to protect the ozone layer

A

Montreal protocol

34
Q

Alternatives to CFCs

A

Coolants- hydrocarbons, ammonia, CO2

HCFCs and HFCs

35
Q

in carboxylic acids, how do you count the chain

A

count from the carbon atom in the -COOH group as being number 1

36
Q

symbol equation for the oxidation of ethanol to ethanoic acid under reflux

A

CH3CH2OH + [O]–> CH3CHO + H2O
CH3CHO + [O] –> CH3COOH
CH3CH2OH + 2[O] –> CH3COOH + H2O

37
Q

why is ethanol added to a haloalkane to determine it

A

it dissolves the haloalkane

38
Q

general equation for radicals affecting the ozone

A

R. + O3 –> RO. + O2
RO. + O –> R + O2

O3 + O –> 2O2

39
Q

what is ozonolysis

A

breaks open a C=C bond

40
Q

what is the purpose of adding sodium carbonate solution to the round bottomed flask

A

neutralises excess acid

41
Q

what is the purpose of adding anhydrous magnesium sulfate

A

acts as a drying agent

Chemistry Cook Y12 (7 decks)

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