Chemical Analysis

Question 1

Formulation

Answer 1

A formulation is a complex mixture that has been designed as a useful product.

Question 2

Give examples of formulations

Answer 2

fuels, cleaning products, paints, medicines, alloys, fertlisisers, and food.

Question 3

What is chromatography used for?

Answer 3

Allows us to seperate substances based on their solubility.

Question 4

which is the stationary phase in chromatography and why?

Answer 4

Paper because it doesn’t move.

Question 5

which is the mobile phase in chromatography and why?

Answer 5

The solvent because it moves up the paper.

Question 6

If there is only one spot on the chromatography paper, what does this mean?

Answer 6

It is a pure substance.

Question 7

If there are multiple spots of the colour seperated into different spots, what does this mean?

Answer 7

Impure substance.

Question 8

Explain how different dyes are seperated by paper chromatography.

Answer 8

• The solvent moves through the paper.
• Different dyes have different solubilities in the solvent
• and different attractions for the paper
• so are carried different distances.

Question 9

Why do we draw our starting line in pencil?

Answer 9

If we drew the line in pen, the pen ink would move up the paper, with the solvent.

Question 10

How do you identify the chemicals in the colours?

Answer 10

-measure the distance from pencil line to the centre of each spot
-measure distance moved by the water from the pencil line
Rf = distance moved by the chemical / distance moved by water
-look up the value in a database and that will tell us the identity of the chemical
-several different chemicals could have the same Rf value
-repeat the experiment using different solvents.