Which process converts \( CH_3CH_2OH \) to \( CH_3COOH \)?
A) bacterial oxidation
B) fermentation
C) catalytic addition of steam
D) catalytic addition of hydrogen
▶️ Answer/Explanation
Ans: A
The question involves converting ethanol (\( CH_3CH_2OH \)) to ethanoic acid (\( CH_3COOH \)), which is an oxidation process.
Let’s evaluate each option:
A) Bacterial oxidation: Correct. When wine is left exposed to air, bacteria oxidize the ethanol to ethanoic acid (vinegar).
B) Fermentation: Incorrect. Fermentation converts sugars to ethanol, not ethanol to ethanoic acid.
C) Catalytic addition of steam: Incorrect. This would hydrate an alkene to form an alcohol, not oxidize an alcohol to a carboxylic acid.
D) Catalytic addition of hydrogen: Incorrect. This would reduce a compound, not oxidize it.
Therefore, only bacterial oxidation (A) correctly describes the conversion of ethanol to ethanoic acid.
The structure of an ester is shown.
Which row identifies the name of the ester and the two compounds from which it is made?
| name | compound 1 | compound 2 | |
|---|---|---|---|
| A | ethyl propanoate | ethanol | propanoic acid |
| B | ethyl propanoate | propanol | ethanoic acid |
| C | propyl ethanoate | ethanol | propanoic acid |
| D | propyl ethanoate | propanol | ethanoic acid |
▶️ Answer/Explanation
Ans: A
Esters are named based on the alcohol and carboxylic acid from which they are formed. The first part of the ester name comes from the alcohol (alkyl group), and the second part comes from the carboxylic acid (with -oate ending).
The structure shown has 2 carbons from the alcohol portion (ethanol) and 3 carbons from the acid portion (propanoic acid). Therefore, the correct name is ethyl propanoate, formed from ethanol and propanoic acid.
Option B incorrectly pairs propanol with ethanoic acid. Options C and D have the ester name reversed (propyl ethanoate would be from propanol and ethanoic acid).
Which processes are used to make ethanoic acid?
1 heating ethanol with acidified aqueous potassium manganate(VII)
2 bacterial oxidation of ethanol
3 distilling ethanol using a fractionating column
A) 1 and 2
B) 1 only
C) 2 and 3
D) 3 only
▶️ Answer/Explanation
Ans: A
Ethanoic acid can be produced by:
1. Oxidation of ethanol using acidified potassium manganate(VII) – this is a standard laboratory method
2. Bacterial fermentation of ethanol – this is how vinegar is made commercially
Distillation (process 3) simply purifies ethanol but doesn’t convert it to ethanoic acid.
Therefore, the correct answer is A (1 and 2 only).
Question
The structure of an ester is shown.
What are the names of the carboxylic acid and the alcohol that react together to form this ester?
Answer/Explanation
Ans:
B