Alcohols

Question 1

What is the bond angle in alcohols?

Answer 1

104.5 degrees

Question 2

What has a higher melting point, alcohols or alkanes?

Answer 2

Alcohols

Question 3

Why do alcohols have a greater melting point than alkanes?

Answer 3

There is hydrogen bonding

Question 4

Are short-chain alcohols soluble in water?

Answer 4

Yes, the hydrogen bonding predominates the non-polar chain.

Question 5

Are long-chain alcohols soluble in water?

Answer 5

No, the non-polar hydrocarbon chain dominates the hydrogen bonding.

Question 6

How do you make ethanol from crude oil?

Answer 6

Ethene is hydrated and a phosphoric acid catalyst is used.

Question 7

How do you make ethanol from fermentation?

Answer 7

• Anaerobic conditions
• Yeast
• 37 degrees

Question 8

What are the products of fermentation?

Answer 8

Ethanol and carbon dioxide

Question 9

How does the purity of ethanol formed differ with hydration or fermentation?

Answer 9

Pure with hydration

Question 10

What process is used for fermentation?

Answer 10

Batch

Question 11

What process is used for hydration?

Answer 11

Continuous

Question 12

What is the method of making ethanol from crude oil?

Answer 12

Cracking and hydration

Question 13

What is the method of making ethanol from carbohydrates?

Answer 13

Fermentation and distillation

Question 14

Define carbon neutral…

Answer 14

No net release of carbon to the atmosphere

Question 15

Why is a purple dye added to methylated spirits?

Answer 15

Show it shouldn’t be drunk

Question 16

What are the 2 ways used to dehydrate alcohols?

Answer 16

Excess hot concentrated sulphuric acid.

Pass vapours over heated aluminium oxide.

Question 17

What are primary alcohols oxidised to?

Answer 17

Aldehydes

Question 18

What are aldehydes oxidised to?

Answer 18

Carboxylic acids

Question 19

What are secondary alcohols oxidised to?

Answer 19

Ketones

Question 20

What are ketones further oxidised to?

Answer 20

Not further oxidised

Question 21

Why are tertiary alcohols no easily oxidised?

Answer 21

A C-C bond would need to be broken.

Question 22

What is characteristic of aldehydes and ketones?

Answer 22

Pleasant smells

Question 23

What is used to oxidise aldehydes to ketones?

Answer 23

Acidified potassium dichromate.

Question 24

What colour change happens in oxidation?

Answer 24

Orange to Green

Question 25

Why does a colour change of Orange to Green occur?

Answer 25

Orange dichromate (VI) ions are reduced to green chromium (III)

Question 26

How do you oxidise ethanol to ethanal?

Answer 26

Use dilute acid and less potassium dichromate (VI) than in needed for complete oxidation is used. Mixture is heated gently with the receiver cooled in ice. Ethanal vaporises as soon as it is formed and distils off.

Question 27

In oxidation, why is the reliever cooled in ice?

Answer 27

To reduce evaporation of the produce.

Question 28

How do you oxidise ethanol of ethanoic acid?

Answer 28

Concentrated sulphuric acid and more than enough potassium dichromate. Mixture is refluxed. Then distilled off by rearranging the apprartus.

Question 29

What is refluxing?

Answer 29

Repeated heated and condensing.

Question 30

What is Fehling's reagent?

Answer 30

Oxidising agent. Contains blue copper (II) complex ions.

Question 31

What equation shows what happens in the Fehling's test?

Answer 31

Cu2+ + e- -> Cu+

Question 32

What is Tollens' reagent?

Answer 32

Oxidising agent. Solution of silver nitrate in aqueous ammonia.

Question 33

What affect does Fehling's reagent have on aldehydes and ketones?

Answer 33

Aldehydes- Blue to brick red | Ketones- No reaction

Question 34

What affect does Tollens' reagent have on aldehydes and ketones?

Answer 34

Aldehydes- Silver mirror | Ketones- No reaction