Question

An organic compound 'A' is used as a preservative in pickles and has molecular
formula C2H4O2. This compound reacts with ethanol to form a sweet smelling
compound 'B'
i)
Determine the compound 'A'.
ii)
Write the chemical equation for its reaction with ethanol to form compound 'B'.
III) Write any two uses of compound 'B'.
IV) Which gas is produced when compound 'A' reacts with washing soda? Write the chemical equation.
v) How can vinegar be obtained from compound 'A'?
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Answer 1

Explanation:

Given -

• An organic compound A is used as a preservative in pickles and has molecular formula C2H4O2.
• The compound reacts with ethanol to form a sweet smelling compound B.

To Find -

1. Determine the compound A
2. write the chemical reaction for its reaction with ethanol to form compound B.
3. write any two uses of compound B
4. which gas is produced when compound A reacts with washing soda. write the chemical equation.
5. How can compound A be obtained from Compound B.

Now,

1)

Ethanoic acid (Acetic acid) is used as a preservative in pickles and has molecular formula C2H4O2.

It means,

compound A is CH3COOH

2)

When Ethanoic acid (acetic acid) reacts with ethanol in the presence of conc. H2SO4 as catalyst then it forms Ethyl ethanoate and water is realesed.

Chemical equation :-

CH3COOH + C2H5OH → CH3COOC2H5 + H2O

It means,

Compound B is Ethyl Ethanoate (CH3COOC2H5)

3)

Uses of Ethyl ethanotate :-

1. It is used in making artificial perfumes.
2. This is used as flavouring agent.

4)

When Ethanoic acid reacts with washing soda (sodium carbonate) then it forms sodium acetate, carbon dioxide and water.

Chemical equation :-

2CH3COOH + Na2CO3 → 2CH3COONa + CO2 + H2O

It means,

CO2 gas is produced when compound A reacts with washing soda.

5)

When Ethyl ethanoate is treated with water then it forms again compound A (Ethanoic acid) and ethanol.

Chemical equation :-

CH3COOC2H5 + H2O → CH3COOH + C2H5OH

Answer 2

Answer :

Compound A with molecular formula C2H4O2 is ethanoic acid, also called acetic acid. Its structural formula is CH3COOH. A dilute solution of acetic acid called vinegar is used as a preservative of pickles.

_________________

(b) Compound A reacts with ethanol to form compound B which is an ester and has a pleasant smell. The reaction is called esterification reaction.

CH3COOH + C2H5OH -----> CH3 COOC2H5 + H2O

Ethanoic acid Ethyl ethanoate

_________________

(c) Compound A can be obtained from ethyl ethanoate by reacting with water in the presence of dilute hydrochloric acid acting as a catalyst.

CH3COOC2H5 + H2O -------> CH3COOH + C2H5OH

Ethyl ethanoate Ethanoic acid

_________________

(d) Process is ester hydrolysis.

_________________

(e) Carbon dioxide is evolved with effervescence when compound A reacts with washing soda.

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