Topic 9- Alcohols

Question 1

Alcohols

Answer 1

Contain the hydroxyl functional group (-OH)

Question 2

Primary Alcohol

Answer 2

Has one alkyl group bonded to the carbon atom that is bonded to the OH group.

Question 3

Secondary Alcohol

Answer 3

Has two alkyl groups bonded to the carbon atom that is bonded to the OH group.

Question 4

Tertiary Alcohol

Answer 4

Has three alkyl groups bonded to the carbon atom that is bonded to the OH group.

Question 5

Production of Alcohol by hydration of alkenes

Answer 5

Hydration of ethene is carried out by using steam and a catalyst.
CH2=CH2 + H2O(g) –> C2H5OH

Question 6

Production of Alcohol by hydration of alkenes
Conditions

Answer 6

• catalyst of concentrated phosphoric acid absorbed on a solid silica surface
• 60 atm pressure
• 600k temperature
• excess ethene to give a high yield
• recycle unreacted ethene and steam back over the catalyst to increase yield.

Question 7

Production of Alcohol by hydration of alkenes
Mechanism

Answer 7

• electrophilic addition

Question 8

Production of Ethanol by fermentation

Answer 8

Yeast converts sugars such as glucose to ethanol and carbon dioxide.
Ethanol produced by fermentation is separated by fractional distillation and can be used as biofuel.
C6H12O6(aq) –> 2CH3CH2OH(aq) + 2CO2(g)

Question 9

Production of Ethanol by fermentation
Conditions

Answer 9

• In the presence of yeast
• Temperature of 35 degrees
• Anaerobic
• In aqueous solution

Question 10

Production of Ethanol by fermentation
Justification of conditions

Answer 10

• Yeast produces an enzyme which converts glucose to ethanol and carbon dioxide.
• Enzyme in yeast has an optimum temperature of 35 degrees.
• No air to prevent oxidation of ethanol formed to vinegar

Question 11

Biofuel

Answer 11

A fuel that is made from renewable plant material.

Question 12

Carbon neutral

Answer 12

When activity results in no net emission of carbon dioxide into the atmosphere.

Question 13

How is ethanol produced by fermentation carbon neutral. (ONLY THEORETICAL)

Answer 13

Six molecules of CO2 removed in photosynthesis.
Four molecules of CO2 released in fermentation, Four molecules of CO2 released in combustion per 2 molecules f ethanol burnt.

Question 14

Oxidation of primary alcohols

Answer 14

Oxidized to aldehydes and then further oxidized to carboxylic acids.
- To obtain aldehyde, heat with oxidizing agent and distill.

Question 15

Equations for oxidation of primary alcohols

Answer 15

C2H5OH + [O] –> CH3CHO + H2O
C2H5OH + 2[O] –> CH3COOH + H2O

Question 16

Oxidation of secondary alcohols

Answer 16

Oxidized to ketone
- Heat under reflux with excess oxidizing agent

Question 17

Equations for oxidation of secondary alcohols

Answer 17

CH3CH(OH)CH3 + [O} –> CH3COCH3 + H2O

Question 18

Oxidation of tertiary alcohols

Answer 18

NO OXIDATION

Question 19

Warm with Tollens` reagent test

Answer 19

Aldehyde - forms a silver mirror on tube, (aldehyde is oxidized to the acid)
Ketone - No reaction, remains a colorless solution.