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Ethanol
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- Ethanol or C2H5OH is a colourless liquid having a pleasant smell.
- It boils at 351 K.
- It is miscible with water in all proportions.
- It is a non-conductor of electricity (it does not contain ions)
- It is neutral to litmus.
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Uses
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- Ethanol is used as an antifreeze in radiators of vehicles in cold countries.
- It is also used as a solvent in the manufacture of paints, dyes, medicines, soaps and synthetic rubber. It is also used as a solvent to prepare the tincture of iodine.
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Reactions of Ethanol with Sodium
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- Ethanol reacts with sodium to produce hydrogen gas and sodium ethoxide. This reaction supports the acidic character of ethanol.
2C2H5OH + 2Na → 2C2H5ONa + H2(↑)
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Reactions to give Unsaturated Hydrocarbon (Dehydration of Ethanol)
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- Ethanol reacts with concentrated sulphuric acid at 443 K to produce ethylene. This reaction is known as dehydration of ethanol because, in this reaction, a water molecule is removed from the ethanol molecule.
CH3CH2OH → CH2=CH2 + H2O
- Ethanol Acid: With molecular formula given as CH3COOH, it dissolves in water, alcohol and ether.
- It often freezes during winter in a cold climate, and therefore, it is named glacial acetic acid.
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Exploring Ethanoic Acid Reactions and the Science Behind Soaps and Detergents
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- Esterification: When a carboxylic acid is refluxed with alcohol in the presence of a small quantity of conc. H2SO4, a sweet-smelling ester is formed.
- This reaction of ester formation is called esterification.
- Saponification: On treatment with sodium hydroxide, which is an alkali, the ester is converted back to alcohol and sodium salt of carboxylic acid.
- This reaction is known as saponification because it is used in the preparation of soap.
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- Soaps are sodium or potassium salts of long chain carboxylic acid.
- Reaction with a Base: Like mineral acids, ethanoic acid reacts with a base such as sodium hydroxide to give a salt (sodium ethanoate or commonly called sodium acetate) and water:
- NaOH + CH3COOH → CH3COONa + H2O
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Reaction with Carbonates and Hydrogen Carbonates
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- Ethanol acid reacts with carbonates and hydrogen carbonates to give rise to salt, carbon dioxide and water.
- The salt produced is commonly called sodium acetate.
2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2
CH3COOH + NaHCO3 → CH3COONa + H2O + CO2
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Soaps and Detergents
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- Most dirt is oily in nature and oil does not dissolve in water.
- The molecules of soap are sodium or potassium salts of long-chain carboxylic acids.
- The ionic-end of soap interacts with water while the carbon chain interacts with oil.
- Micelles: The soap molecules, thus form structures called micelles where one end of the molecules is towards the oil droplet while the ionic-end faces outside.
- Emulsion: This forms an emulsion in water. The soap micelle thus helps in pulling out the dirt in water and we can wash our clothes clean
- Properties: Soaps are molecules in which the two ends have differing properties, one is hydrophilic, that is, it interacts with water, while the other end is hydrophobic, that is, it interacts with hydrocarbons.
- Soap on Surface: When soap is at the surface of water, the hydrophobic ‘tail’ of soap will not be soluble in water and the soap will align along the surface of water with the ionic end in water and the hydrocarbon ‘tail’ protruding out of water.
- Soap Inside Water: Inside water, these molecules have a unique orientation that keeps the hydrocarbon portion out of the water.
- Thus, clusters of molecules in which the hydrophobic tails are in the interior of the cluster and the ionic ends are on the surface of the cluster.
- This formation is called a micelle.
- Soap in the form of a micelle is able to clean, since the oily dirt will be collected in the center of the micelle.
- Repulsion: The micelles stay in solution as a colloid and will not come together to precipitate because of ion-ion repulsion.
- Thus, the dirt suspended in the micelles is also easily rinsed away.
- The soap micelles are large enough to scatter light. Hence a soap solution appears cloudy.
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