paper chromatography

What does paper chromatography allow you to do?

Separate substances based on their different solubilities

describe process of required practical for paper chromatograph?

1)on chromotography/filter paper using a pencil draw a line (baseline) near the the bottom of a sheet

2)add sample of ink to the baseline

3)using beaker fill with a shallow amount of solvent(water/ ethanol)

4) place paper into the solvent making sure we don’t submerge pencil line and ink

5)place lid on top of container/ beaker to stop solvent from evaporating

6) the solvent now makes its way/seeps under the paper and it dissolves ink in the dots , now ink is carried up the paper dissolved in the solvent

7) the different dyes in the ink will move up paper at different rates , so dyes will separate out and form spots in different places

What is the point the solvent has reached as it move up the paper called

Solvent front

What are the two phases called what are they and why?

Stationary phase- is the paper bc the paper doesn’t move

Mobile phase - is the solvent bc the solvent moves

What type of process is chromotography? And what is the definition of that process

A physical process - does not involve chemical reactions and no new substances are made

What does it mean if only one spot appears

The ink is a single pure colour

What happens if multiple spots appear

The ink is a mixture of different colours

What does a pure compound produce?

A single spot in all solvents

What do compounds in a mixture do?

Separate into different spots depending on the solvent

Why does paper chromatography work?

Because different substances have different solubilites

A more soluble substance is more attracted to the mobile phase then a less soluble substance

So more soluble travels further than substances which is less soluble

Why do we draw starting line in pencil?

Bc the pen ink could dissolve in the solvent and move up the paper

Pencil marks are also insoluble and won’t dissolve in the solvent