Question

Chemical test to distinguish between phenol and ethanoic acid

Answer 1

Chemical test to distinguish between

 a) Phenol and Acetic acid

NaHCO3 test: When both are reacted with NaHCO3, acetic acid gives brisk effervescence due to liberation of CO2 gas. But phenol does not give any reaction with NaHCO3.

CH3COOH + NaHCO3 ----> CH3COONa + CO2 + H2O 

C6H5OH + NaHCO3 ------> no evolution of CO2gas

b) Formaldehyde and Acetaldehyde

Iodoform test: When both are treated with iodine in presence of alkali, acetaldehyde gives white ppt. of iodoform but formaldehyde not.

CH3CHO + 4NaOH  + 3I2 ----> CHI3  + HCOONa + 3NaI + 3H2O

HCHO + 4NaOH  + 3I2 ----> No Iodoform

c) Formic acid and Acetic acid

Tollen's reagent test : When both are treated with Tollen's reagent, formic acid reduces Tollen's reagent to metallic silver but acetic acid doesn't.

 HCOOH + 2[Ag(NH3)2]+ + 2OH- ---> 2Ag + CO2+ 2H2O + 4NH3

CH3COOH + [Ag(NH3)2]+ ----> no silver mirror

d) Propanoyl Chloride and Propanoic acid

Add a few drops of water to both.

Propanoyl chloride will hydrolyze to give acid and white fumes of HCl. But there will be no fumes in case of Propanoic acid.

CH3CH2COCl + H2O ----> CH3CH2COOH + HCl

CH3CH2COOH + H2O ----> No fumes of HCl

Suggest chemical test to distinguish between a) Phenol and Acetic acid b) Formaldehyde and Acetaldehyde c) Formic acid and Acetic acid d) Propanoyl