explain the steps in simple paper chromatography process
Answers
Answer:
Step 1: A horizontal line is drawn near one end (about 1.5 cm from the bottom edge) of the paper. ...
Step 2: The sample needs to be separated is placed as a small drop or line on to the paper using capillary tube. ...
Step 3: The paper is then placed into a sealed container with a swallow layer of suitable solvent.
Step 1: A horizontal line is drawn near one end (about 1.5 cm from the bottom edge) of the paper. In figure below 6 is the horizontal line.
By No machine-readable author provided. Dubaj~commonswiki assumed (based on copyright claims). [Public domain], via Wikimedia Commons
Step 2: The sample needs to be separated is placed as a small drop or line on to the paper using capillary tube. Labelling the drop by a pencil with an alphabet or number help to identify the compound later. In figure above 3 and 4 are the drops labelled. The drops are then soaked on the paper and dried.
Step 3: The paper is then placed into a sealed container with a swallow layer of suitable solvent. The solvent level must be lower than the pencil line or drop on it. The container need to be covered to stop the solvent to evaporate.
Step 4: The solvent rises up the paper chromatography taking each component of the sample with it. The components travel with the solvent depends on three things:
The polarity of the sample molecule. The non polar components travel faster than the polar component.
The attraction between the sample molecule and the solvent or solvent mixture.
The attraction between the sample and the silica.
Suppose any sample compound mixture contains three colored molecules green, blue and red. According to their polarity, the order of these compounds is green<blue<red. Thus the most non polar green will travel first along with the mobile phase. Then blue and at last most polar compound the red one.
Step 5: When the solvent rises near the end of the paper then the paper should be taken out from sealed container and air dried. The paper with separated bands of components are then observed under UV-light.
Rf value
The compounds in the sample travels along with solvent to give separate bands on the paper. The distance travelled by same compound with respect to the solvent is always constant. Thus the ratio of the distance that the compound travelled and the distance that the solvent travelled is denoted as Rf. And mathematically expressed as: