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A level chemistry > 4.2 Alcohols, haloalkanes and analysis > Flashcards

4.2 Alcohols, haloalkanes and analysis Flashcards

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1
Q

What is the definition of a primary alcohol

A

Where the functional group is attached to a carbon atom with o more than one alkyl group q

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2
Q

What is the definition of a secondary alcohol

A

Where the functional group is attached to a carbon with 2 alkyl groups

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3
Q

What is the definition of a tertiary alcohol

A

Where the functional group is attached to a carbon with 3 alkyl groups

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4
Q

How do the boiling points of alcohols and their corresponding alkanes differ

A

Hydrogen bonds between the alcohol molecules require more energy to overcome

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5
Q

Describe the volatility of alcohols

A

Alcohols aren’t as volatile as alkenes as they have higher boiling points and volatility decreases as boiling point increases

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6
Q

Describe the solubility of alcohols as you go down the homologous series

A

Alcohol group is polar so methanol, ethanol and propanol are soluble in water

A carbon chain increases the solubility decreases because the aliphatic chain cannot form hydrogen bonds at it makes up most of the molecule

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7
Q

What is the product when you oxidise a primary alcohol

A

1° alcohol (distillation) —> Aldehyde
1° alcohol (reflux) —> carboxylic acid

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8
Q

What is the product when you oxidise a secondary alcohol

A

2° alcohol (reflux) —> ketone

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9
Q

What is the product when you oxides a 3° alcohol

A

Nothing

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10
Q

Give examples of oxidising agents

A

acidified potassium dichromate - orange to dark green
Tollens reagent - silver mirror (aldehyde –> carboxylic acid)

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11
Q

Describe a dehydration reaction and its conditions

A

1° or 2° alcohols —> alkene + H2O

170°C and acid catalyst e.g. H2SO4

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12
Q

How do you make an ester

A

alcohol + carboxylic acid —> ester (-oate) + water
50°C and H2SO4 catalyst

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13
Q

How do you draw an ester from its name

A

Identify parent acid and alcohol

Draw displayed acid first then alcohol (opposite to name )

Take OH from acid and H from alcohol

                                O
                                 II Draw new structure R-C-O
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14
Q

What are the two ways to make ethanol

A

Fermentation
Hydration

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15
Q

Describe how we make ethanol via fermentation

A

Conditions :
35°C 1atm Zymase catalyst (yeast)

glucose —> ethanol + carbon dioxide

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16
Q

Describe how we make ethanol via hydration

A

Conditions
300°C 70atm concentrated phosphoric acid catalyst

alkene + water (steam) —> ethanol

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17
Q

what type of process is fermentation

A

batch

18
Q

what type of process is ethene reaction with steam

A

continuous

19
Q

What is the reaction rate and purity of ethanol in fermentation

A

slow
impure

20
Q

What is the reaction rate and purity of ethanol during the ethene reaction with steam

A

fast
pure

21
Q

what is the definition of a primary haloalkane

A

the halogen is on the end of the alkyl chain

22
Q

what is the definition of a nucleophile

A

an electron pair donor

23
Q

what affects the reactivity of haloalkanes

A

the electronegativity of the halogen can make the molecule more polar

the higher the mean bond enthalpy the less likely the halide will react in a nucleophilic substitution reaction

24
Q

what is the definition of nucleophilic substitution

A

a reaction where an atom or a group of atoms is exchanged for a nucleophile

25
Q

what kind of fission does water undergo during hydrolysis of haloalkanes

A

heterolytic fission to produce the nucleophile OH-

26
Q

how do we measure hydrolysis

A

add the haloalkane and ethanol AgNO3 and water to a test tube and heat in a water bath.
Start the timer and note down when a precipitate is formed
AgCl- white
AgBr- cream
AgI - yellow

27
Q

how do we perform hydrolysis using aqueous alkali

A

e.g. NaOH and heat
it will dissociate into OH- and Na+
this is also a nucleophilic substitution reaction

28
Q

what happens to the bonds in cfcs in the atmosphere

A

the C-Cl bond in C2F2Cl2 undergoes homolytic fission due to the UV radiation

C2F2Cl2 —> C2F2Cl• + Cl•

29
Q

why is the ozone layer beneficial to us

A

it absorbs all of the UV - C radiation and most of the UV-B radiation protecting us from genetic damage and skin cancer

30
Q

why are CFCs bas for the atmosphere

A

the chlorine radicals catalyse the breakdown of ozone to diatomic oxygen molecules and 1 CFC molecule can destroy 100,000 ozone molecules

31
Q

What is the equation that shows the breakdown of ozone molecules

A

Cl•+ O3–> O2+ClO•
ClO•+O3–>Cl•+2O2

32
Q

How can other radicals affect the ozone

A

nitrogen oxides (made from the high temperatures in exhaust engines and lighting) can also catalyse the breakdown of ozone to diatomic oxygen

33
Q

Gove the equation that depicts the breakdown of ozone caused by other radicals

A

NO•+O3–> NO2•+O2
NO2•+O—> O2+NO•

34
Q

give examples of drying agents

A

magnesium sulfate MgSO4
calcium chloride CaCl2

35
Q

What is the test for alkenes

A

bromine water
orange to colourless

36
Q

What is the test for a haloalkane

A

add silver nitrate, water and ethanol and a precipitate will form

37
Q

how do you test for a carbonyl

A

ketones have no changes with all of the tests below but aldehydes do

acidified potassium dichromate orange to dark green

tollens reagent silver mirror

fehlings solution dark red precipitate

38
Q

How do you test for a carboxylic acid

A

add universal indicator bc its slightly acidic

add a reactive metal and there will be effervescence

39
Q

How do you test for and alcohol

A

Warm with a carboxylic acid and some H2SO4 and there will be a sweet smelling ester produced

40
Q

give two examples of organic compounds with more that one functional group

A

aspirin — has a carboxylic acid and aromatic ring

niacin— has a carboxylic acid and pyridine group

A level chemistry (14 decks)

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