Carbon and Its Compounds

Harmful effects of ethanol

1. Consumption of its small quantity causes drunkenness.
   
2. It depresses the central nervous system which results in mental confusion and drowsiness.
   
3. It damages liver and kidney.
   
4. It decreases the sense of judgment and sense of timing.
   
5. It increases crime in the society.
   

Denatured alcohol To prevent the misuse of ethanol produced for industrial use, it is made unfit for drinking by adding poisonous substances like methanol, copper sulphate, etc. it is called denatured alcohol.

ETHANOIC ACID (acetic acid or vinegar, CH₃COOH)

Physical properties.

1. It is a colourless and pungent smelling liquid.
   
2. Its melting point is 290K so it often freezes during winter and looks like glacier. Therefore, it is also known as glacial acetic acid.
   
3. It is soluble in water in all proportions.
   5% to 8% solution of Ethanoic acid in water is called vinegar.
   

Chemical properties

1. Reaction with alcohol. Ethanoic acid reacts with ethanol in the presence of an acid to give ester.

CH₂COOH + C₂H₅OH Acid CH₃COOC₂H₅ + H₂O

2. Reaction with base. Ethanoic acid reacts with sodium hydroxide to give sodium ethanoate (sodium acetate) and water.
   

CH₃COOH + NaOH CH₃OONa + H₂O

3. Reaction with carbonates and bicarbonates. Ethanoic acid reacts with carbonates and bicarbonates to salt carbon dioxide and water.
   

2CH3COOH + Na2CO3 2CH3COONa + CO2 + H2O
CH3COOH + NaHCO3 CH3COONa + CO2 + H2O

Esterification The reaction between a carboxylic acid and an alcohol to form an ester is called Esterification reaction.

CH₂COOH + C₂H₅OH Acid CH₃COOC₂H₅ + H₂O

• The reaction between the ester and hot base to give original alcohol and carboxylic acid back is called saponification reaction because this reaction is used in preparing soaps.
  

CH₃COOC₂H₅ NaOH CH₂COOH + C₂H₅OH

The product formed when a carboxylic acid reacts with an alcohol having the formula R-COO-R’ is called an ester. Esters are sweet smelling substances. They are widely spread in nature. The smell of fruits and flowers is due to the presence of esters. Esters are used as flavorings agents and in making perfumes.

Cleansing action of soap The molecules of soap are sodium or potassium salts of long chain of carboxylic acids. The hydrocarbon tail being hydrophobic reacts with oil or grease while the ionic end being hydrophilic reacts with water. As a result micelles are formed. They form an emulsion in water.
When the surface of clothes is beaten or agitated, micelles are thrown away and the cloth is cleaned.

Micelle The cluster of about 100 – 200 molecules with hydrophilic ends on the surface of cluster and hydrophobic ends towards the centre, is called a micelle.

Soaps	Detergents
Soaps are sodium salts of long chain carboxylic acids.	Detergents are sodium salts of long chain sulphonic acids.
Soaps do not form leather with hard water.	Detergents form leather with hard water.
Soaps are biodegradable.	They are non biodegradable.
Soaps do not have strong cleansing action.	They have strong cleansing action.
These are prepared from animal fats.	They are prepared from hydrocarbons of petroleum.

Advantage of soaps over detergents Soaps are biodegradable so they do not produce pollution. While detergents being non biodegradable produce pollution.

Advantage of detergents over soaps Detergents can be used in hard water. Also, they have strong cleansing action. While soaps have weak cleansing action and they cannot be used in hard water.