GCSE 1.9 Chromatography

What is the definition of a mixture?

• A combination of two or more substances that are not chemically bonded.

• A substance made of only one type of atom.

• A chemical reaction between two elements.

• A process of separating components of a compound.

Why should we draw the origin line in pencil?

• To make it easily erasable

• pencil is insoluble in water and will not affect the experiment

• To make the ink spots easier to see

• pencil is soluble in water and will combine with the ink spots

A capillary tube is used to transfer the ink samples to the chromatogram because:

• It allows for precise measurement.

• It prevents contamination.

• It is faster than other methods.

• Only a small amount of each ink sample is needed

The solvent moves up the paper. What phase is the paper?

• Stationary phase

• Mobile phase

• Gas phase

• Liquid phase

What would happen if the solvent level was higher than the ink samples?

• The ink samples would dissolve.

• The ink samples would float.

• The ink samples would not move off the baseline

• The ink samples would evaporate.

Why is it necessary to note where the solvent gets to at the end of the experiment?

• To ensure accurate measurements

• To record the experiment's progress

• When the solvent dries you will not be able to tell how far it travelled

• To determine the experiment's success

An ink sample does not move off the baseline and didn’t separate into any colours in the mixture. Why?

• It was too soluble in the solvent

• It was not soluble in the solvent

• It reacted with the origin line.

• It was already separated.

A compound has an Rf value of 0.6. If the solvent travels 16.0cm up the chromatography paper, how far did the compound travel ( in cm)?

• 26.67cm

• 0.96cm

• 9.6cm

• 2.7cm

What is the purpose of using a solvent in chromatography?

• To dissolve the paper

• To separate the components of the mixture

• To color the samples

• To fix the samples on the paper

Which factor does NOT affect the Rf value of a compound?

• The type of solvent used

• The temperature of the environment

• The length of the paper

• The nature of the stationary phase