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प्रश्न
How is the following sol prepared?
Collodion
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उत्तर
Method: Dispersion Method
Collodion sol is prepared by dispersing nitrocellulose (guncotton) in a suitable solvent mixture.
Procedure: First, nitrocellulose is prepared by treating cotton (cellulose) with a nitrating mixture of concentrated nitric acid and concentrated sulphuric acid.
Chemical Reaction:
\[\ce{Cellulose + HNO3 + H2SO4 -> \underset{Nitrocellulose}{C6H7O2(ONO2)3} + H2O}\]
About 4% of nitrocellulose is then dissolved in a 1 : 1 mixture of alcohol and ether. This forms a clear, colloidal dispersion known as collodion.
The collodion solution is slowly added to water with constant stirring. As the solvents (ether and alcohol) diffuse into water, colloidal particles of nitrocellulose are formed and get dispersed.
