Alcohols

Question 1

Name?

Answer 1

2-hydroxypropanenitrile

Question 2

Whats a carbonyl group?

Answer 2

molecule containing C=O

Question 3

What’s an aldehyde?
Structural formula?
Naming?

Answer 3

R–CH=O
…CHO
…al

Question 4

What’s a ketone?
Structural formula?
Naming?

Answer 4

R–C=O–R
…CO
…one

Question 5

What’s a carboxylic acid?
Structural formula?
Naming?

Answer 5

R–C=O–OH
…COOH
…oic acid

Question 6

What 2 different methods are used to produce ethanol in the industry?

Answer 6

• Direct hydration
• Fermentation

Question 7

What are the reagents + conditions for direct hydration?

Answer 7

Reagent: Conc. H3PO4 catalyst, steam
Conditions: 450 degrees, 50-100atm pressure

Question 8

Fermentation reaction equation?

Reagent + Conditions needed?

Answer 8

C6H12O6 —–> 2CH3CH2OH + 2CO

Reagent: Glucose
Conditions: Yeast enzymes, 35 degrees, no oxygen

Question 9

Explain why neither low or high temperature Is suitable for fermentation reaction?

Answer 9

Too cold - rate of reaction is too slow

Too high - enzymes denature + stop working

Question 10

Pros + cons to production of ethanol through fermentation?

Answer 10

Advantages:
- Uses renewable resources (glucose)
- Lower temperatures require less energy cost
- Simpler equipment required is cheaper

Disadvantages:
- Slow RoR
- Land used to grow crops isn’t available for food crops
- Low yield
- Batch production is difficult to automate
- Ethanol is impure so needs to be distilled

Question 11

Pros + cons to production of ethanol through direct hydration?

Answer 11

Advantages:
- High-purity ethanol produced
- Continuous production
- Fast RoR

Disadvantages:
- Crude oil is non-renewable
- High temperature + pressure requires energy
- High tech equipment

Question 12

What are the following to go from Alcohol to Alkene in one step?

• Reaction
• Mechanism
• Conditions

Answer 12

• Dehydration
• Elimination
• Hot conc. H2SO4 (catalyst)

Question 13

Elimination mechanism with ethanol to ethene?

Answer 13

Question 14

What is the observation for alcohol oxidisation when acidified K2Cr2O7 is added?

Answer 14

Orange to Green

Question 15

State the reagents + conditions needed to make a primary alcohol into an aldehyde?

Answer 15

Reagent: Acidified K2Cr2O7
Conditions: Heat under distillation

Question 16

State the reagents + conditions needed to make an aldehyde into a carboxylic acid?

Answer 16

Reagent: Acidified K2Cr2O7
Conditions: Heat under reflux

Question 17

State the reagents + conditions needed to make a primary alcohol into a carboxylic acid?

Answer 17

Reagent: Acidified K2Cr2O7
Conditions: Heat under reflux, excess oxidising agent

Question 18

State the reagents + conditions needed to make a secondary alcohol into a ketone?

Answer 18

Reagent: Acidified K2Cr2O7
Conditions: Heat under reflux or distillation

Question 19

Out of primary alcohol, aldehyde + carboxylic acid, which one has the lowest boiling point? Why?

Answer 19

Aldehyde - permanent dipole-dipole forces, weakest IMF

Primary alcohol + carboxylic acid - hydrogen bonding

Question 20

Reflux apparatus?

Answer 20

Question 21

Distillation apparatus?

Answer 21

Question 22

Reagent used to test for aldehydes? (2)
Observation when not/present?

Answer 22

Tollen’s Reagent - [Ag(NH3)2]+
Present - Silver mirror forms
Not - No visible change

Fehling’s Solution - blue Cu2+
Present - Brick-red precipitate
Not - No visible change

Question 23

Reagent used to test for carboxylic acids?
Observation when not/present?

Answer 23

Sodium Carbonate - Na2CO3
Present - effervescence
Not - No visible change

Question 24

There are 3 problems with the apparatus of fractional distillation. For each problem:

• Identify the problem
• Describe the issue it would cause
• Suggest how the problem can be solved

Answer 24

1) Anti-bumping granules:
- Add anti-bumping granules
- To create smaller bubbles/ prevent large bubbles

2) Open system with no thermometer:
- System should be closed to prevent gases escaping
- Closed with a bung and a thermometer
- To allow collection of propanone

3) The water direction in the condenser:
- Change water direction
- Condenser isn’t cool enough
- Product may not condense

Question 25

Explain why pentan-2-ol has a higher boiling point than pent-1-ene? (3)

Answer 25

• Idea that pentan-2-ol has stronger intermolecular forces
• Pent-1-ene has induced dipole-dipole forces (only)
• Pentan-2-ol (also) has hydrogen bonds

Question 26

Explain why nonane has a higher boiling point than 2,4-dimethylheptane? (2)

Answer 26

• Nonane has permanent dipole-dipole forces between molecules that are stronger than 2,4-dimethylheptane’s induced dipole-dipole forces
• Nonane has more surface contact area