An orange drink concentrate is suspected to contain traces of poisonous green dye and a harmless dye having the same boiling point. Which of the following techniques is most suitable for isolating the dyes?

Edefua

1 year ago

The correct answer is:

B. Paper chromatography
Chromatography is ideal for separating and identifying components in a mixture, especially dyes and pigments.
In this case, the two dyes in the orange drink concentrate are suspected to have:
1. The same boiling point (so distillation won't work).
2. Different solubility or interaction properties with a solvent (mobile phase) and the paper (stationary phase).

Paper chromatography works by applying the sample to a paper, introducing a solvent (mobile phase), and allowing the dyes to migrate at different rates due to their differences in polarity, size, or solubility. This separation allows the identification of the poisonous green dye.


•Why Not the Other Options?

1. Fractional Distillation:
This separates substances based on differences in boiling points. Since the two dyes have the same boiling point, this method is ineffective.


2. Coagulation:
Coagulation is used to clump together particles suspended in a liquid, like impurities in water, but it cannot separate or isolate soluble dyes in a drink.

3. Recrystallization:
Recrystallization separates components based on their solubility in a solvent at different temperatures. While useful for purifying solids, it is not effective for separating soluble dyes with similar physical properties in a liquid concentrate.


How Paper Chromatography Works:
1. Sample Application: A small amount of the orange drink concentrate is applied to a paper strip as a spot.
2. Development: The paper is placed in a solvent, which moves up by capillary action.
3. Separation: The dyes travel at different rates depending on their affinity to the solvent and the paper.
4. Detection: The separated dyes appear as distinct spots, which can be identified by their color or using chemical reagents.

°This makes paper chromatography the most suitable technique for isolating and identifying the dyes.