Why is the chromatography paper hung with the bottom just in the water?

Because you want the products to be carried by the front of solvent but do not want to dilute your spot with your solvent.

Where should the water come up to on the paper in chromatography?

The water should touch the very end of the paper towel, but not the ink. Tape the paper towels in place and wait to see what happens. The water should creep up the paper towel strips and separate each ink mark into a cool dye pattern. This is called chromatography.

Why must the base line be placed above the level of the water at the start?

The start line above the solvent level allows the solvent to move past the start line, carrying the dissolved samples along with it.

Why is the eluent level below the sample marker?

The solvent should not touch the spots when the separation first begins, that’s why its level should be below the spots by at least 0.5 cm. Cover the container and wait for elution to proceed. By capillary action, the solvent will immediately start rising up the TLC plate.

Why is water not used in chromatography?

The eluent is usually an organic solvent or mixture of solvents. The eluent can be more polar or less polar. For that reason, methanol and water are not normally used as the eluent. If the solid phase is stationary, then when compounds are absorbed onto the solid, they will not move either.

Why is the line drawn in pencil in chromatography?

In paper chromatography, a starting line in drawn on the paper in pencil (pencil so that it does not dissolve in the solvent and affect the results). Small spots of each sample are placed on the starting line. If a substance is more strongly attracted to the paper than the solvent then it will move a short distance.

Why is water used in chromatography?

Water is the reagent used in the largest volumes in Liquid chromatography and its purity is critical, especially in high sensitivity applications. These will require water for sample pre-treatment, such as solid phase extraction, and for the preparation of eluents, reagent blanks and standards.

What does the water act as in chromatography?

Water acts as a polar mobile phase in chromatography.

Why must the solvent start below the base line on the TLC plate?

The solvent level has to be below the starting line of the TLC, otherwise the spots will dissolve away. Non-polar solvents will force non-polar compounds to the top of the plate, because the compounds dissolve well and do not interact with the polar stationary phase.

Why must the water level in the beaker be below the spots?

It is important that the solvent level is below the line with the spots on it. The reason for covering the container is to make sure that the atmosphere in the beaker is saturated with solvent vapour. Saturating the atmosphere in the beaker with vapour stops the solvent from evaporating as it rises up the paper.

Why must the solvent be below the starting line?

Why is it important to keep the solvent below the 2 cm line at the bottom of the chromatography paper?

It is important that the solvent level is below the line with the spots on it. As the solvent slowly travels up the paper, the different components of the ink mixtures travel at different rates and the mixtures are separated into different coloured spots.

What is the principle involved in paper chromatography?

Paper Chromatography Principle The principle involved can be partition chromatography or adsorption chromatography. Partition chromatography because the substances are partitioned or distributed between liquid phases. The two phases are water held in pores of the filter paper and the other phase is a mobile phase which passes through the paper.

How do you prepare filter paper for chromatography?

Selecting a suitable filter paper: Selection of filter paper is done based on the size of the pores and the sample quality. Prepare the sample: Sample preparation includes the dissolution of the sample in a suitable solvent (inert with the sample under analysis) used in making the mobile phase.

Can you use a pen to draw lines on chromatography paper?

In chemistry, a pen is not used to draw lines on chromatography paper. A pencil is used to draw lines on the paper because the ink can smear and interfere with the chromatography and the ink will dissolve in the chromatography solvent. In thin layer chromatography why is it important to line the tank with filter paper?

Why is the base line important in paper chromatography?

This is so you can know the base line. The base line is used as the starting point for the mesaurements used for the Rf values. you need to know the distance from the base line to the point of the spot to know the Rf values. see related link below for more info about paper chromatography How does paper chromatography separate the molecules?