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Aldehydes Ketones and Carboxylic Acids question

2009 · Shift 0 · Q13
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Aldehydes Ketones and Carboxylic Acids question

2009 · Shift 0 · Q13

JEE MainChemistryAldehydes Ketones and Carboxylic AcidsMCQ+4 / −1
A liquid was mixed with ethanol and a drop of concentrated H2SO4H_2SO_4H2​SO4​ was added. A compound with a fruity smell was formed. The liquid was :
  1. A
    CH3OHCH_3OHCH3​OH
  2. B
    HCHO
  3. C
    CH3COCH_3COCH3​CO CH3CH_3CH3​
  4. D
    CH3COOHCH_3COOHCH3​COOH
View written solutionFree

Correct answer: D

  1. The reaction described is:

    • A liquid is mixed with ethanol
    • A drop of concentrated H2SO4H_2SO_4H2​SO4​ is added
    • A compound with a fruity smell is formed

  2. A fruity smell is characteristic of an ester.

  3. Esters are formed when a carboxylic acid reacts with an alcohol in the presence of concentrated H2SO4H_2SO_4H2​SO4​.

    The general reaction is: RCOOH+R′OH→conc. H2SO4RCOOR′+H2ORCOOH + R'OH \xrightarrow[\text{conc. }H_2SO_4]{} RCOOR' + H_2ORCOOH+R′OHconc. H2​SO4​​RCOOR′+H2​O

  4. Here, the alcohol is ethanol, C2H5OHC_2H_5OHC2​H5​OH. So the given liquid must be a carboxylic acid.

  5. Check the options:

    • A: CH3OHCH_3OHCH3​OH = methanol, an alcohol, does not give ester with ethanol directly.
    • B: HCHO = formaldehyde, an aldehyde, does not form fruity-smelling ester with ethanol under these conditions.
    • C: CH3COCH3CH_3COCH_3CH3​COCH3​ = acetone, a ketone, does not form ester with ethanol under these conditions.
    • D: CH3COOHCH_3COOHCH3​COOH = acetic acid, a carboxylic acid, reacts with ethanol to form ethyl acetate.

  6. Reaction: CH3COOH+C2H5OH→conc. H2SO4CH3COOC2H5+H2OCH_3COOH + C_2H_5OH \xrightarrow[\text{conc. }H_2SO_4]{} CH_3COOC_2H_5 + H_2OCH3​COOH+C2​H5​OHconc. H2​SO4​​CH3​COOC2​H5​+H2​O

  7. Ethyl acetate has a pleasant fruity smell.

Therefore, the liquid was: CH3COOH\boxed{CH_3COOH}CH3​COOH​

So, the correct option is D.

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