CBSE Chemistry Subject Notes

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Chemistry

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Carbon and Its Compounds

 

ETHANOIC ACID ( ACETIC ACID - CH3COOH )

A dilute solution of ethanoic acid in water is called vinegar .

Physical properties :-

  1. Colourless liquid having a sour taste and a smell of vinegar.
  2. Boiling point is 118°C
  3. On cooling , it freezes to form a colorless , ice-like solid ( like glacier) so it is also called glacial ethanoic / acetic acid.
  4. Miscible with water in all proportions.

Chemical Properties  :-

  1. Action on litmus- Turns blue litmus  red ; universal indicator paper to orange ( 4 pH)  showing it is a weak acid.
  2. Reaction with Carbonates and Hydrogencarbonates :-
    1. With Sodium Carbonate � Forms sodium ethanoate ( sodium acetate ) and CO2 gas.
      2CH3COOH + Na2CO3 ? 2 CH3COONa + CO2 + H2O
    2. With Sodium Hydrogencarbonate - Forms sodium ethanoate and evolves brisk effervescence of CO2 gas.
      CH3COOH + NaHCO3 ? CH3COONa + CO2 + H2O
  3. Reaction with Sodium Hydroxide -- It reacts with bases to form salt and water .
    CH3COOH + NaOH ? CH3COONa + H2O
    ( sodium ethanoate)
  4. Reaction with Alcohols - Reacts in presence of a little of Con. H2SO4 to form esters.
    CH3COOH + C2H5OH ? CH3COOC2H5 + H2O
    Sweet smelling ester is formed. Esters are volatile liquids having sweet / pleasant / fruity smell . They are used to make artificial perfumes , flavours and essences .
Esters can be hydrolysed back to the alcohol and carboxylic acid when heated with sodium hydroxide solution.

SOAPS  AND  DETERGENTS

Detergent – Any substance which has cleansing action in water.
Two types  ---  Soapy and Non soapy ( detergents)

Soaps  -- Sodium or potassium salt of a long chain carboxylic acid( fatty acid) which has cleansing properties in water. It has a large non-ionic hydrocarbon group and an ionic group  , COONa.
Eg. Sodium Stearate – C17 H35COONa
       Sodium Palmitate  -  C15H31COONa

  • Soap is the salt of a strong base ( sodium hydroxide) and a weak acid So a solution of soap in water is basic in nature.

 

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Submitted By Mrs. Kritika Bhola
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