Chromatography Concepts and Techniques

Which natural substance, found in willow leaves, was historically used to treat joint pain?

• Acetylsalicylic acid

• Salicylic acid

• Paroxetine

• Cellulose

What are the two main components required for any chromatography technique to separate mixtures?

• Reactants and products

• Acids and bases

• Stationary phase and mobile phase

• Solute and solvent

What is the primary component of the paper used as the stationary phase in paper chromatography, and what is its key property?

• Plastic, non-polar

• Cellulose, polar

• Alumina, non-polar

• Silica gel, polar

How is the Retention Factor (Rf) calculated in chromatography?

• Distance traveled by solvent front divided by distance traveled by spot

• Distance traveled by spot multiplied by distance traveled by solvent front

• Distance traveled by spot divided by distance traveled by solvent front

• Distance traveled by spot plus distance traveled by solvent front

What is the Rf value if a compound travels 10 mm and the solvent front travels 64 mm on a Thin Layer Chromatography (TLC) plate?

• 0.10

• 0.16

• 0.64

• 1.60

What is the main purpose of using Thin Layer Chromatography (TLC) to monitor a chemical reaction?

• To measure the exact temperature of the reaction.

• To check if the starting materials have been used up and if new products have formed.

• To determine the exact mass of the products formed.

• To increase the speed of the chemical reaction.

How can compounds that are not naturally colored be seen on a TLC plate after separation?

• By heating the plate with a Bunsen burner.

• By shining UV light on the plate or using chemical stains.

• By adding water to the plate.

• By placing the plate in a dark room.

What is the purpose of applying pressure with an air hose during flash chromatography?

• To cool down the column and prevent overheating.

• To force the solvent and separated compounds through the silica gel.

• To mix the sample more thoroughly with the stationary phase.

• To prevent the column from going dry.