Practicals

Question 1

Describe the process of preparing a pure organic solid (e.g. aspirin)

Answer 1

1. dissolve the impure sample in a minimal volume of hot solvent
2. filter hot solution through filter paper
3. cool the filtrate by inserting beaker into ice
4. filter under reduced pressure
5. wash the crystals with cool solvent

Question 2

When preparing a pure organic solid, why wash the crystals in cold solvent?

Answer 2

remove soluble impurities

Question 3

When preparing a pure organic solid, why use a minimal volume of hot solvent?

Answer 3

hot to dissolve the compound and impurities, minimal volume required to get a concentrated solution so solution is saturated

Question 4

When preparing a pure organic solid, why filter the hot solution through filter paper?

Answer 4

remove insoluble impurities