Question

In paper chromatography, (a) Mobile phase is liquid and stationary phase is solid (b) Mobile phase is solid and stationary phase in solid (c) Mobile phase is liquid and stationary phase is liquid (d) Mobile phase is solid and stationary phase is liquid.

Short answer

(a) Mobile phase is liquid and stationary phase is solid.

Step-by-step solution

Understanding Chromatography Terms

In paper chromatography, substances are separated based on differential partitioning between the mobile phase and the stationary phase. The mobile phase is the substance that moves and carries the different components to be separated, and the stationary phase is the substance that remains fixed and interacts with the components to effect separation.

Identify the Mobile Phase in Paper Chromatography

The mobile phase in paper chromatography is a liquid solvent or mixture of solvents that moves through or along the stationary phase, carrying different substances with it.

Identify the Stationary Phase in Paper Chromatography

In paper chromatography, the stationary phase is solid, which is usually the water trapped in the fibers of cellulose paper or the cellulose itself acting as an adsorbent.

Matching Options to Definitions

Given that in paper chromatography, the mobile phase is a liquid and the stationary phase is a solid, the correct option must match this configuration. The correct answer is (a) Mobile phase is liquid and stationary phase is solid.

Key concepts

Mobile Phase

In paper chromatography, the mobile phase is the component that moves. This is often a liquid solvent or a mixture of solvents. It acts like a transporter, carrying different substances over the stationary phase. The goal here is to separate various components of a mixture.

As the mobile phase travels through the chromatography setup, it drags along with it the components to be separated. The speed at which a component moves depends on its level of interaction with both the mobile and the stationary phase.

The choice of solvent is crucial. A suitable solvent ensures efficient separation by appropriately interacting with the different substances within the mix.

Stationary Phase

In contrast to the mobile phase, the stationary phase in paper chromatography doesn't move. In this method, cellulose paper serves as the stationary phase. It remains fixed throughout the process, allowing substances to interact with it as they are carried by the mobile phase.

This interaction with the stationary phase is what aids in separating different components. Different substances will either stick to the paper or travel with the mobile phase to different extents, based on their nature and affinity.

• A strong interaction with the stationary phase will slow down a component.
• A weak interaction may allow a component to move more quickly and further.

Liquid Solvent

The liquid solvent is key to the functioning of the mobile phase. This solvent carries the different chemicals or pigments that need to be separated. Selecting the right solvent strictly depends on the nature of the components to be separated. Each solvent has different properties:

• Polarity: Determines how well the solvent interacts with certain substances.
• Solubility: Influences which substances can dissolve and move with the mobile phase.
• Volatility: Affects how fast the solvent will evaporate during the process.

The solvent needs to effectively dissolve the substances and interact optimally with both phases for efficient separation.

Cellulose Paper

Cellulose paper is a critical component in paper chromatography, serving as the stationary phase. It acts as a support where substances interact and eventually separate.

The cellulose fibers in the paper are what primarily influence the separation. They trap water molecules, and this water often participates as part of the stationary phase.

• Adsorption: Cellulose fibers can adsorb substances, affecting their movement.
• Porosity: The paper's porous nature aids in the movement and separation of substances.

This characteristic allows cellulose paper to play a dual role of supporting paper and interacting medium.