Understanding Paper Chromatography

What is the main purpose of chromatography?

• To measure the mass of a substance

• To separate and identify substances in a mixture

• To increase the temperature of a solution

• To evaporate solvents quickly

Why is a pencil used to draw the line on chromatography paper instead of a pen?

• Pencil is more colourful

• Pencil does not dissolve in the solvent

• Pen ink helps the dyes move faster

• Pencil is heavier than pen

Which of the following best describes the solvent front in paper chromatography?

• The starting point of the ink spot

• The highest point reached by the solvent on the paper

• The bottom of the chromatography paper

• The point where the paper dries

What does it mean if two dyes have the same Rf value in the same solvent?

• They are definitely different substances

• They are likely to be the same substance

• They have different solubilities

• They have different colours

Which factor affects how far a dye travels up the chromatography paper?

• The temperature of the room

• The solubility of the dye in the solvent

• The thickness of the paper

• The amount of light in the room

If the solvent front moves 10 cm and a dye spot moves 5 cm, what is the Rf value?

• 0.2

• 0.5

• 2.0

• 5.0

Why must the ink spot be above the level of the solvent at the start of the experiment?

• To prevent the ink from dissolving in the solvent

• To allow the solvent to carry the dyes up the paper

• To keep the paper dry

• To make the colours brighter

What is a chromatogram?

• The solvent used in chromatography

• The pattern of spots formed on the paper after separation

• The line drawn with pencil

• The container used for the experiment

Which of the following is NOT a suitable solvent for paper chromatography?

• Water

• Ethanol

• Cooking oil

• A mixture of water and ethanol

What is the correct formula for calculating the Rf value in chromatography?