Alcohols

Question 1

Name

H–CH(OH)–CN

Answer 1

2-hydroxyethanenitrile

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

https://studymind.co.uk/notes/alcohol-reactivity/#:~:text=Elimination,gets%20eliminated%20forming%20an%20alkene.&text=As%20shown%20in%20the%20diagram,and%20an%20H%20get%20lost.

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

https://tdck.weebly.com/uploads/7/7/0/5/77052163/experimental_procedures_organic.pdf

Question 21

Distillation apparatus?

Answer 21

https://pmt.physicsandmathstutor.com/download/Chemistry/A-level/Notes/AQA/Practical-Skills/RP%2005%20-%20Distillation%20of%20a%20reaction%20product.pdf

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