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CHEMISTRY A LEVEL > CHAPTER 14 - ALCOHOLS > Flashcards

CHAPTER 14 - ALCOHOLS Flashcards

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1
Q

What do alcohols contain?

A

-OH functional group - Hydroxyl group

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2
Q

What is the formula for methanol

A

CH3OH

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3
Q

What is methanol used for

A

High performance fuel (efficient combustion)
Chemical feedstock
Converted into polymers, paints, solvents, insulation, adhesives etc…

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4
Q

What is Ethanol used for

A

Alcoholic drinks
Solvent
Fuel
Feedstock

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5
Q

What is the suffix used for an alcohol

A

-ol (diol, triol etc..)

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6
Q

What are the physical properties of alcohols compared to the Alkanes with the same amount of carbons (eg methane and methanol)

A

Alcohols are:
Less volatile
Higher MP/BP (pg 223 for diagram)
Greater water solubility
(Differences become smaller as chain length increases)

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7
Q

Why do alcohols act differently to alkanes?

A

The alkane have non-polar bonds
Very Weak London Forces (LDF)
Alcohols are polar
Strong H bonds, Very weak LDF

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8
Q

Why are Alcohols soluble in water

A

Form Hydrogen bonds in water
Polar groups -OH

(Increase in carbon chain, decrease in solubility)

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9
Q

What does Ethylene Glycol (ethane 1,2 diol) do and how does it work?

A

De-Icer
Water freezes at 0 and ethane diol at -13, but when combined, freezing point can be as low as -40, which means that the frozen waster changes state

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10
Q

How can alcohols be classified?

A

Primary, Secondary, Tertiary

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11
Q

What is a primary alcohol?

A

When the carbon which the -OH group is attached to is attached to 2/3 other Hydrogens (no or one alkyl group) (eg. Ethanol, Methanol)

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12
Q

What is a secondary alcohol?

A

When the carbon which the -OH Group is attached to is only attached to 1 Hydrogen or 2 carbon (or 2 alkyl groups) (eg Pentan-3-ol)

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13
Q

What is a tertiary alcohol?

A

When the carbon which the -OH Group is attached to no Hydrogens or 3 carbons (or 3 alkyl groups) (eg 2-methylpropan-2-ol)

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14
Q

What is the word equation for the combustion of alcohols

A

Alcohol + Oxygen = Carbon dioxide and water

Eg. C2H5OH + 3 O2 = 2 CO2 + 3 H2O

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15
Q

What type of reaction is the combustion of alcohols

A

Exothermic, releases large quantity of energy from heat

Increase in carbon chain increase in heat released per mole

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16
Q

What colour change does the oxidation of alcohols undergo?

A

Orange - Green

Dichromate (VI) ions - Chromium (III) ions

17
Q

What is added to the alcohols for them to be oxidised?

A

acidified K2Cr2O7 and dilute H2SO4

18
Q

What do Primary alcohols oxidise to?

A

Aldehydes, then further to Carboxylic acid

19
Q

How is an Aldehyde prepared?

A

Heating of a primary alcohol with acidified potassium dichromate and dilute sulfuric acid

Distilled off - to prevent further oxidation

20
Q

How is a carboxylic acid prepared

A

Heating of a primary alcohol with acidified potassium dichromate and dilute sulfuric acid under reflux conditions

21
Q

What is produced in the oxidation of a secondary alcohol?

A

Ketone

22
Q

How is a Ketone prepared

A

Heating of a secondary alcohol with acidified potassium dichromate and dilute sulfuric acid
Under reflux conditions
Change from orange to green

23
Q

What happens when a tertiary alcohol is oxidised?

A

Nothing - they do not oxidise
Solution remains orange

24
Q

What is formed when an alcohol is dehydrated?

A

Alkene and water

25
Q

What is needed as reagents for the dehydration of alcohol?

A

Acid catalyst eg. conc Phosphoric acid or conc sulfuric acid

Reflux conditions

26
Q

What type of reaction is Dehydration?

A

Elimination reaction

27
Q

What is formed when alcohols react with hydrogen halides

A

Haloalkanes and water

28
Q

How is a Haloalkane prepared?

A

Alcohol in reflux conditions with added sulfuric acid and a sodium halide (eg HBr)

(page 228 for diagram)

CHEMISTRY A LEVEL (14 decks)

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