Problem 27 - A Complete Resource Book in Chemistry for JEE Main

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.

Step-by-Step Solution

Answer

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

Step 1: Understanding Chromatography

Chromatography is a technique used to separate mixtures into their individual components. It involves a mobile phase, which is a fluid carrying the mixture, and a stationary phase, which does not move and interacts with the substances in the mixture.

Step 2: Identifying the Phases in Paper Chromatography

In paper chromatography, the stationary phase is the paper itself, which is a solid. The mobile phase, which moves through the stationary phase, is a liquid solvent.

Step 3: Matching the Phases with Options

Compare the understanding of paper chromatography phases with the given options. In option (a), the mobile phase is a liquid, and the stationary phase is a solid, which matches paper chromatography.

Key Concepts

Chromatography Technique

Chromatography is a fascinating and vital analytical technique used in chemistry and biology to separate and analyze complex mixtures. Imagine trying to untangle a box of different colored threads. Chromatography helps by separating these threads based on specific properties.
In this method, mixtures are dissolved in a "mobile phase," which moves through a "stationary phase." These phases work together to carry out the separation process, where different substances travel at different speeds. This leads to them becoming separated as they interact with the stationary phase.
There are many types of chromatography, such as paper chromatography, gas chromatography, and liquid chromatography. Each type uses different materials and conditions to perform the separation, but all rely on the fundamental principle of differential movement. This characteristic movement helps scientists identify the composition of the mixture and allows for the isolation of specific components.

Mobile Phase in Chromatography

The mobile phase in chromatography is the part that moves. It carries the mixture to be separated through the stationary phase. The role of the mobile phase is to dissolve the sample components and transport them at different rates. Think of it as a river that carries different boats down its stream.
In paper chromatography in particular, the mobile phase is typically a liquid solvent. This solvent works its way up the absorbent paper, which is the stationary phase, helping the components of the mixture move along the paper to different extents.

• The speed at which a component travels depends on its solubility in the mobile phase.
• More soluble substances will move faster and further along the stationary phase.

Therefore, selecting the right solvent for the mobile phase is crucial to achieving effective separation.

Stationary Phase in Chromatography

The stationary phase is the part of the chromatography system that does not move. It provides a surface for the mobile phase and the substances carried by it to interact and separate.
Specifically, in paper chromatography, the stationary phase is solid and involves the use of a strip or sheet of paper. This paper acts as a platform where separation occurs. The nature of the paper, including its thickness and absorbency, plays a significant role in how effectively components are separated.

• Interactions between the stationary phase and the different substances in the mixture can affect the time it takes for each substance to travel.
• Components that interact more with the paper will move slower than those that do not interact much.

Understanding the characteristics of the stationary phase is important, as it directly affects the resolution and efficiency of the separation process.