Organic (U2)

Question 1

What is the general formula for alcohols?

Answer 1

CnH2n+1OH

Question 2

Give examples of common alcohols and their structures.

Answer 2

• Methanol: CH3OH
• Pentanol: C5H11OH

Question 3

What are the two main ways to prepare ethanol?

Answer 3

• Hydration of ethene (fast & pure but expensive)
• Fermentation of glucose (cheap but slow)

Question 4

Why is fermentation a batch process?

Answer 4

The yeast dies at 15% alcohol concentration, requiring the process to be restarted.

Question 5

Why can’t fermentation occur in the presence of oxygen?

Answer 5

1. Oxygen would oxidize ethanol to ethanoic acid (vinegar taste).
2. Yeast wouldn’t anaerobically resipre so no ethanol produced

Question 6

What are the main reactions of alcohols?

Answer 6

• Combustion: C2H5OH + 3O2 → 2CO2 + 3H2O
• Dehydration: C2H8OH → C2H4 + H2O (H3PO4 catalyst, 300°C, 65 atm)
• Oxidation: Ethanol + Oxygen → Water + Ethanoic Acid

Question 7

What is the general formula for carboxylic acids?

Answer 7

CnH2n+1COOH

Question 8

Give examples of carboxylic acids and their structures.

Answer 8

• Methanoic Acid: HCOOH
• Pentanoic Acid: C4H9COOH

Question 9

How are carboxylic acids prepared?

Answer 9

Oxidation of alcohols: C2H5OH + 1/2O2 → CH3COOH + H2O

Question 10

What are the key reactions of carboxylic acids?

Answer 10

• Acid + Base → Salt + Water
• Acid + Metal → Salt + Hydrogen
• Acid + Carbonate → Salt + Water + CO2
• Esterification: CH3COOH + C2H5OH → CH3COOC2H5 + H2O

Question 11

What are esters used for?

Answer 11

Food flavoring & perfumes (sweet-smelling oils).

Question 12

How do you name esters?

Answer 12

• Alcohol part ends in “yl” (first in name)
• Acid part ends in “anoate” (first in name)
• In molecular and displayed, acid comes first

Question 13

Convert the following molecular formulae to ester names:
1. C3H7COOC2H5
2. C4H9COOC3H7

Answer 13

1. Ethyl Butanoate
2. Propyl Pentanoate

Question 14

What happens in addition polymerization?

Answer 14

Monomers join by breaking double bonds (alkenes).

Question 15

What are some common addition polymers and their uses?

Answer 15

Name | Monomer| Uses
1. Poly(ethene) | Ethene | Plastic bottles
2. Poly(chloroethene) / PVC |Chloroethene |Electrical insulation
3. Poly(propene) | Propene | Fizzy drink bottles
4. Poly(tetrafluoride) / Teflon | Tetrafluoride |Non-stick pans

Question 16

How does condensation polymerization differ from addition polymerization?

Answer 16

• Addition polymerization only forms a polymer.
• Condensation polymerization forms a polymer and water per link.

Question 17

What are polyesters made from?

Answer 17

Dicarboxylic acids (COOH at both ends) + Diols (OH at both ends).

Question 18

How do you determine the monomers from a polyester?

Answer 18

Break at the C-O bond and restore H/OH groups.

Question 19

Why do polymers cause pollution?

Answer 19

They are non-biodegradable and don’t naturally break down.

Question 20

What are the main problems with plastic waste?

Answer 20

• Landfills: Take up space, ruin landscapes.
• Incineration: Produces CO2, and PVC releases toxic HCl gas.
• Incomplete combustion: Produces toxic carbon monoxide.
• Recycling: Difficult and expensive (polymers must be separated).