Separtion by paper chromatography

In summary, it is important not to permit the solvent front to reach the top of the chromatogram because it can disrupt the ratios used in calculations. Additionally, keeping the indicator spots small ensures efficient separation and avoids overlapping of components. Using acid-base indicators as substrates instead of common substances like sugar or salt is beneficial because they are colorless in solution, making it easier to track their movement.
  • #1
moonlight1
8
0
Hi does anyone know why it is imporatnt not to permit the solvent front to reach the top of the chromatogram?
 
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  • #2
When the solvent reaches the top, it totally screws up your ratios. Before reaching the top, you can say the components move X distance for every Y distance the solvent moves. Now that the solvent can't move anymore, that ratio doesn't apply, so you can no longer calculate that ratio. You would have to start over again.
 
  • #3
Then why is it impotant to keep the indictor spots very small? is it beacuse separation is efficient?
 
  • #4
If you use too much sample for the spots, you get huge streaks, and the different parts can overlap. Suppose 3 dots are supposed to come out, one is blue, one is yellow, and one is green. If you use too much, you'll get big yellow and blue streaks that overlap to make a greenish area. Is the desired green component even there, or is the green area just overlap of yellow and blue? How can you tell?
 
  • #5
Whats the point to use acid-base indicators as the subanctes instead of more commom substances such as sugar or salt?

is it casue its colorless in soultion so we canot track their movement
 

1. What is separation by paper chromatography?

Separation by paper chromatography is a technique used to separate and identify different components of a mixture based on their different rates of movement through a specialized paper. This is achieved by using a mobile phase (solvent) to carry the components up the paper, and a stationary phase (paper) to separate the components based on their different affinities for the phases.

2. What are the materials needed for paper chromatography?

The materials needed for paper chromatography include a piece of specialized chromatography paper, a container for the solvent, a solvent (such as water or alcohol), and the mixture to be separated. Other materials that may be needed include a ruler, pencil, and paper clips to mark and suspend the paper in the solvent.

3. How does paper chromatography work?

Paper chromatography works by separating components of a mixture based on their different rates of movement through the paper. This is due to the different affinities the components have for the mobile and stationary phases. Components with a higher affinity for the mobile phase will move further up the paper, while those with a higher affinity for the stationary phase will remain closer to the starting point.

4. What factors can affect the results of paper chromatography?

Several factors can affect the results of paper chromatography, including the type of paper used, the composition of the solvent, the temperature, and the size and shape of the molecules being separated. Other factors that may influence the results include the distance the solvent travels up the paper and the drying time of the paper.

5. What are some common applications of paper chromatography?

Paper chromatography has a wide range of applications in various fields, including biochemistry, forensic science, and environmental science. It is commonly used to separate and identify amino acids, sugars, and plant pigments. It can also be used to analyze unknown substances found at a crime scene or to detect contaminants in water samples.

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