explain how paper chromatography separates the components in a solution
This is more than a simple explanation but it explains the different kinds of paper chromatography. In general, the solid phase (in this case the paper) and the mobile phase (can be water or some other solvent) have different affinities for various compounds. So a mixture of materials is placed in the paper, dried, and subjected to the solvent. As the solvent moves up the paper by capillary action, the components having greater affinity for the paper are held back while those having greater affinity for the solvent move. The result is a separation of the components of the mixture. Here is the site that described it is much more detail. http://en.wikipedia.org/wiki/Paper_chromatography
Paper chromatography is a technique used to separate the different components present in a solution. It relies on the principle of differential solubility, where different substances have different affinities for the mobile phase (solvent) and the stationary phase (paper). The overall process involves three main steps: preparation, development, and analysis.
1. Preparation:
- Firstly, a piece of filter paper or chromatography paper is taken and a small spot of the mixture to be separated is applied using a capillary tube or a dropper. This spot is called the origin.
- Next, the paper is allowed to dry completely.
2. Development:
- The chromatography paper is placed vertically in a container with a suitable solvent, ensuring that the spot is above the level of the solvent.
- The solvent chosen must be compatible with the substances being separated and should have the ability to move up the paper.
- As the solvent travels up the paper by capillary action, it carries the different components of the mixture along with it.
- The components in the mixture have varying solubilities in the solvent. Some components will have higher affinity for the solvent and will move faster, while others will have higher affinity for the paper and will move slower.
- As the solvent rises up the paper, it creates a mobile phase, carrying the components at different rates.
- Over time, the components separate and form distinct regions or bands on the paper.
3. Analysis:
- Once the development process is complete, the paper is removed from the container and allowed to dry.
- The separated components are often invisible, so appropriate detection methods are applied.
- One way to visualize the components is to use a visualization technique, such as dipping the paper in a solution or spraying it with a reagent that reacts with specific compounds. This causes the separated components to become visible as colored spots.
- The different spots represent individual components that were present in the original mixture.
- The distance traveled by each spot from the origin (or the solvent front) can be measured, which can provide information about the relative solubility and mobility of the components.
In summary, paper chromatography separates the components in a solution based on their varying solubilities in the solvent and their affinity for the paper. By using a suitable solvent and careful analysis of the separated components, scientists are able to identify and quantify the different substances present in a mixture.