Practicals - WIM

Question 1

How is product prepared and separated? (synthesis of organic solid)

Answer 1

1 - Heat reactants under reflux
2 - Add anti-bumping granules to mixture
3 - Suction filtrate product to separate it

Question 2

How is organic solid purified + dried? (synthesis of organic solid)

Answer 2

1 - Dissolve in min vol. hot solvent
2 - Filter sol. by gravity filtration (removes insoluble impurities)
3 - Allow sol. cool + crystalise
4 - Suction filtrate
5 - Rinse with cold solvent (remove aqueous impurities)
6 - Dry in desiccator with drying agent

Question 3

How is purity checked? (synthesis of organic solid)

Answer 3

1 - Solid in Mpt tube sealed at one end
2 - Place in Mpt apparatus + heat slowly
3 - Record temp when it starts to melt + finished melting
4 - Repeat + average temps
5 - Large range between start + finish = more impure, low temp = more impure

Question 4

Why is % yield less than 100%? (synthesis of organic solid)

Answer 4

1 - Product lost in purification steps

2 - Product lost when transferring between apparatus

Question 5

Describe Chromatography?

Answer 5

1 - Pencil line bottom plate
2 - Add drop sample on watch glass + dissolve in few drops solvent
- Use capillary tube to place spot on pencil line
- Repeat for pure sample
3 - Place plate in beaker solvent (solvent can’t go over pencil line)
- Cover with lid
4 - Leave for 30 mins
5 - Mark where solvent has traveled on plate (solvent line) + remove from solvent
6 - Allow plate to dry
7 - Either:
a - Use UV to find loc. spots
b - Place in gaseous I(2) spots brown
8 - Calculate Rf value

Question 6

How can chromatography be used to check purity?

Answer 6

Carry out with pure + impure sample + compare Rf

Question 7

Rf value equation?

Answer 7

distance moves by spot/ distance moves by solvent