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
The chromatograph line is drawn in pencil because pencil marks are more permanent and less likely to smudge when in contact with the organic solvents used in chromatography. Ink can dissolve or spread when exposed to these solvents, affecting the accuracy of the chromatogram.
If the solvent level reaches the pencil line where the spots are, it can dissolve the compounds in the mixture, causing them to spread out and overlap. This can lead to inaccurate results and difficulties in analyzing the separated components on the chromatogram. It's important to maintain the separation of the compounds on the chromatography plate for clear identification.
The material in a pencil is typically graphite, a form of carbon that leaves a mark when drawn on paper. The graphite is mixed with clay to create the pencil "lead" that is encased in the wooden barrel of the pencil. The hardness of the lead can vary, producing different shades and line thicknesses.
The main element found in pencil lead is graphite. This form of carbon is mixed with clay to create the core of a pencil. Other elements, such as small amounts of wax or additives, may also be used in the production of pencil lead.
Submerging the chromatography paper above the pencil line would cause the solvent to rise above the line, potentially leading to the ink or pigment above the line to dissolve and be carried upwards with the solvent. This can result in the separation of different components within the ink or pigment.
The chromatograph line is drawn in pencil because pencil marks are more permanent and less likely to smudge when in contact with the organic solvents used in chromatography. Ink can dissolve or spread when exposed to these solvents, affecting the accuracy of the chromatogram.
If the solvent level reaches the pencil line where the spots are, it can dissolve the compounds in the mixture, causing them to spread out and overlap. This can lead to inaccurate results and difficulties in analyzing the separated components on the chromatogram. It's important to maintain the separation of the compounds on the chromatography plate for clear identification.
The baseline where dyes are placed in a chromatogram is typically not drawn with a pen because the ink from the pen could potentially interfere with the separation of the dyes. Using a pen may introduce additional components into the chromatogram that can affect the accuracy and reliability of the analysis. Instead, a pencil or other non-reactive marking tool is typically used to mark the baseline.
No it is not.
because the pen or marker will run and the pencil will not.Did this answer your question(if this did not you are a complete idiot):)
A pencil line is a mark made by a pencil when it is pressed against a surface, leaving behind a trail of graphite. It is usually used for drawing or writing.
So the drawing is a very fine line and easy to rub out?
Civil ingineer pencil
The piece of lead in a pencil or the pencil.
draw it with a pencil
A pencil, possibly! A pencil, possibly! A pencil, possibly! A pencil, possibly!
not neccessarily, because you can create line art with different medias such as ink. Line art, i think is the usage of lines to create a hidden image. Pencil art is, of course, usage of the glorious pencil.