How will you separate the components of a black ink?
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Solution
Separating different components of ink:
A black ink is a mixture of two or more water soluble coloured components.
The suitable technique to separate the different components of ink is paper chromatography.
Paper chromatography: When a strip of filter paper is used to carry out chromatography, it is known as paper chromatography.
Chromatography: The technique of separation and purification of the different coloured components of a mixture due to the difference in their extent of solubility in the solvent used for chromatography.
Principle used in this technique is that the components to be separated are soluble in the same solvent but at different rates.
Process of paper chromatography:
A thin strip of filter paper is cut out and a line is drawn on it approximately 3 cm above the lower end of the filter paper. This line is called a reference line.
A small dot of ink is placed in the centre of the line drawn.
Once the dot of ink is dry, it is lowered into the chromatography jar containing water.
The filter paper should be immersed in such a way that the dot of ink is above the water level in the jar.
The set-up should be left undisturbed for some time.
As the water starts to rise up from the lower end of the filter paper, the component of ink which is more soluble in the water rises faster and higher up on the filter paper. The level up to which water rises is known as water front.
Depending on the number of components present in the ink, some coloured spots are observed corresponding to the separated components of the ink.
