PUMPA - THE SMART LEARNING APP

Helps you to prepare for any school test or exam

Download now on Google Play
Ethanoic acid (\(CH_3COOH\)), commonly known as acetic acid, is one of the most important compounds of the carboxylic acid circle of relatives. Its molecular formula is \(C_2H_4O_2\). The structural formula for ethanoic acid is,
 
34.png
Ethanoic acid
 
Preparation of ethanoic acid:
 
Ethanoic acid is prepared on a large scale through the oxidation of ethanol in the presence of alkaline potassium permanganate or acidified potassium dichromate.
 
CH3CH2OH2[O]KMnO4/OHCH3COOH+H2OEthanolEthanoicacid
 
Physical properties of ethanoic acid:
  • Colourless liquid with a strong odour.
  • Acids are sour in taste, and so is ethanoic acid.
  • They are miscible in water irrespective of their proportions.
  • They have a higher boiling point than the corresponding groups of aldehyde, alcohol and ketones.
  • Pure ethanoic acid on cooling forms ice-like flakes. As it resembles glaciers, it is known as glacial acetic acid.
Chemical properties of ethanoic acid:
  
a) Reaction with metal:
  
The reaction of active metals (such as Na, Zn, etc.) with ethanoic acid forms ethanoate with the liberation of hydrogen gas.
 
\(2CH_3COOH + Zn \rightarrow (CH_3COO)_2Zn + H_2\)
                                                  Zinc ethanoate

 
\(2CH_3COOH + 2Na \rightarrow 2CH_3COONa + H_2\)
                                                  Sodium ethanoate
  
b) Reaction with carbonates and bicarbonates:
 
Ethanoic acid reacts with weak bases such as sodium carbonate (\(Na_2CO_3\)) and sodium bicarbonate (\(NaHCO_3\)), forming its salt, water along with the liberation of brisk effervescence (\(CO_2\)).
 
\(2CH_3COOH + NaCO_3 \rightarrow  2CH_3COONa + CO_2 + H_2O\)
                                                  Sodium ethanoate
 
\(CH_3COOH + NaHCO_3 \rightarrow  CH_3COONa + CO_2 + H_2O\)
                                                  Sodium ethanoate
  
c) Reaction with base:
  
Sodium ethanoate and water is formed when ethanoic acid reacts with sodium hydroxide.
 
\(CH_3COOH + NaOH \rightarrow  CH_3COONa + H_2O\)
                                                  Sodium ethanoate
  
d) Decarboxylation (removal of \(CO_2\)):
  
The reaction of soda lime (solid mixture of 3 parts of \(NaOH\) and one part of \(CaO\)) with the sodium salt of ethanoic acid produces methane gas.
 
\(CH_3COOH \xrightarrow {NaOH /CaO} CH_4+ Na_2CO_3\)
                                                      Methane
                                                        gas
 
Uses of ethanoic acid:
  • Lower concentrations of acetic acid (vinegar) are used as a food additive, flavouring agent, and preservative.
  • They are used in the manufacturing of plastics.
  • Used in making dyes, pigments and paints.
  • It is used as a laboratory reagent and for printing on fabrics.
  • They are also used for coagulating rubber from latex.
  • Ethanoic acid is used in the production of pharmaceuticals.