2. Experimental Techniques

Question 0

Describe paper chromatography

Answer 0

The mixture is put on a filter paper that is placed in a suitable solvent
As the solvent rises up the filter paper, the individual components within the mixture are separated

Question 1

Describe the purpose paper chromatography

Answer 1

It is a separation technique that is used to separate and identify the components of a mixture
Used to identify coloring agents

Question 2

How is the locating agent used and its purpose

Answer 2

Use to identify colorless substances
Chromatography paper is dried and sprayed with locating agent
The locating agent reacts with the chemicals in the colorless spot and colored compound us formed
The color is usually developed by warming the paper in oven

Question 3

How do we know if a substance is pure?

Answer 3

▫️Pure substance have distinct MP&BP
▫️If a substance is impure, the impurities will have ab affect in the MP and BP
▫️The further distance away from the MP and BP, the more impure the substance

Question 4

Describe filtration

Answer 4

▫️An undissolved solid can be separated from a solution or liquid by passing through a piece of filter paper in a filter funnel

Question 5

Purpose of crystallisation

Answer 5

Use to obtain a crystalline solid from a solution

Question 6

How is crystallisation done?

Answer 6

▫️the solution is gently heated in an evaporating basin to concentrate it
▫️the solvent is evaporated until the crystallisation point is reached
▫️the concentrated solution is then left to cool
▫️crystals eventually form at the bottom of the evaporating basin
▫️these can be filtered off and dried between pieces of filter paper