Chromatography And Its Principles

The correct answer is (C) : Visualisation agent as a component of mobile phase.
The function of mobile phase is to carry the components present on TLC.

Chromatography is a technique used for the separation of components in a mixture based on their different affinities towards a stationary phase while being transported by a mobile phase. Different chromatographic techniques employ different principles for separation, one of which is differential adsorption.

1. Understanding Differential Adsorption:
   • Differential adsorption is based on the varying degrees to which different components in a mixture adhere to a stationary phase.
   • Components that strongly adsorb onto the stationary phase move more slowly compared to those with weaker adsorption, leading to their separation.
2. Analysis of Options:
   • Column Chromatography (A):
     • It utilizes a column packed with a stationary phase (e.g., silica or alumina) and separates compounds based on differential adsorption to the stationary phase.
     • Components that have stronger interactions with the stationary phase will travel slowly through the column.
   • Thin Layer Chromatography (B):
     • Similar to column chromatography, TLC also operates on the principle of differential adsorption.
     • A thin layer of adsorbent (typically silica gel) is spread over a glass or plastic plate, and separation occurs based on adsorbent interactions.
   • Paper Chromatography (C):
     • This technique primarily uses the principle of partition rather than adsorption.
     • Separation is based on differences in solubility and paper as a stationary phase is impregnated with a liquid stationary phase.
3. Conclusion:
   • Column Chromatography and Thin Layer Chromatography both rely on differential adsorption principles.
   • Therefore, the correct answer is A & B only.

The problem asks for the calculation of the retardation factor (Rf) of an organic compound based on the distances it and the solvent moved on a thin layer chromatographic plate. The final answer needs to be expressed in a specific format.

Concept Used:

In thin layer chromatography (TLC), the retardation factor, denoted as , is a ratio that quantifies the movement of a compound relative to the movement of the solvent front. It is a characteristic property of a compound for a given stationary phase (the TLC plate coating) and mobile phase (the solvent). The formula to calculate the retardation factor is:

The value is always between 0 and 1, as the compound can never travel farther than the solvent front.

Step-by-Step Solution:

Step 1: Identify the given values from the problem statement.

The distance moved by the organic compound (solute) is given as 3.5 cm.

The distance moved by the solvent (mobile phase) is given as 5 cm.

Step 2: Substitute these values into the formula for the retardation factor .

Step 3: Calculate the numerical value of the retardation factor.

Step 4: Express the calculated value in the required format of .

To convert 0.7 into the desired format, we can write it as:

Since is equal to , we have:

Final Computation & Result:

The retardation factor is calculated as the ratio of the distance moved by the compound to the distance moved by the solvent.

Expressing this in the specified format:

Thus, the retardation factor of the organic compound is 7 .