Why is water not suitable solvent in paper of chromatography ?

Water is not a suitable solvent in paper chromatography because it can cause the paper to become too wet and fragile, leading to the paper breaking or tearing during the chromatography process. Additionally, water may not be able to effectively separate the components of the mixture being analyzed, as it may not have the appropriate polarity or solubility properties to interact with the components in the mixture. Other solvents, such as ethanol or acetone, are often used in paper chromatography because they are better able to separate the components of a mixture and do not damage the paper substrate.

Water is not a suitable solvent in paper chromatography because it is:

- Too Polar: Water is a highly polar solvent, meaning it has a strong affinity for polar molecules. This high polarity makes it difficult to separate nonpolar or weakly polar compounds, which are the types of compounds typically analyzed using paper chromatography.

- Interferes with Separation: Water interacts with the cellulose fibers of the paper, causing them to swell and distort. This swelling and distortion can interfere with the separation of the analytes, leading to inaccurate or inconsistent results.

- Poor Solvent Mobility: Water has a high surface tension and low volatility, which makes it move slowly through the paper. This slow movement can result in long separation times and poor resolution of the analytes.

- Can Dissolve the Sample: Some samples may dissolve in water, which would prevent them from being separated by paper chromatography.

Therefore, nonpolar or weakly polar solvents such as hexane, chloroform, or ethyl acetate are typically used as solvents in paper chromatography. These solvents have a lower affinity for water, do not interact strongly with the paper fibers, and have better solvent mobility, resulting in better separation of nonpolar and weakly polar compounds.