Ethanoic acid

Ethanoic Acid (CH ₃ COOH):

• It is also known as acetic acid.
• It is the 2nd member of a homologous series of carboxylic acid.
• Dilute solution of ethanoic acid is called vinegar.  

a. Physical Properties:

• It is a colorless liquid having a sour taste and the smell of vinegar. 
• It has a higher boiling point as compared to ethanol i.e. 118 ^o C .
• When ethanoic acid freezes, it forms an ice-like solid. Therefore, it is also known as glacial acetic acid .
• It is also highly soluble in water.
• Since ethanoic acid is acidic in nature, it turns blue litmus red. However, it is a weaker acid as compared to hydrochloric acid (HCl).

b. Chemical properties: 

• Reaction with carbonates and hydrogen carbonates:
  Ethanoic acid reacts with sodium carbonate and sodium hydrogen carbonate to yield salt, water and carbon dioxide gas. The reactions are as follows:
  This reaction is used as a test for carboxylic acids because CO 2 gas is released with brisk effervescence and it turns lime water milky.

• Reaction with sodium hydroxide:

Ethanoic acid reacts with bases to form salt and water.

• Reaction with Alcohols (Esterification reaction ):
  Ethanoic acid reacts with alcohol in the presence of a small amount of concentrated sulphuric acid to form esters which have a fruity smell . Because ester is formed in this reaction, the process is known as esterification.
  Hydrolysis of esters: When esters are heated with NaOH the ester breaks down/hydrolyses to give carboxylic acid and alcohol.

Uses of Ethanoic Acid:

1. It is used in preparation of dyes, plastics and pharmaceuticals.
2. Used for manufacture of acetone and esters used in perfume.
3. Vinegar which is diluted ethanoic acid is used in food preparation and preservation.