Paper 3 - practical techniques

Question 1

How to obtain impure solid from hot reaction mixture

Answer 1

• Cool

* Filter under reduced pressure

Question 2

Recrystallisation (method)

Answer 2

• Dissolve impure solid in minimum volume of hot water/solvent
• Cool solution and filter solid
• Wash with cold water/solvent and then dry

Question 3

How to check for purity

Answer 3

• Obtain melting point
• Compare to known values
• Pure sample will have melting point close to the data book value